Star Flung From Milky Way at High Speed

fenimor writes "Using the MMT Observatory in Tucson, astronomers have discovered a star three times bigger than the sun, leaving our galaxy at a speed of over 1.5 million miles per hour (670 kilometers per second). The first-of-its-kind finding not only confirms an earlier theory about the existence of such speeding stars, but also reinforces the notion that the Milky Way spins around a black hole."

Comments

That's Life

[Doc Ruby]

It's a glider!

Re:That's Life

[Loadmaster]

It's a big ball of garbage from Old New York. I checked it with my smell-o-scope.

Re:That's Life

[Ohreally_factor]

Actually, this supports my theory that the galaxy is just one big irc channel. I'm going to keep running bash.org through seti@home in hopes of finding some intelligent life.

Re:That's Life

[Rosyna]

No, it's Trance's sun hurtling towards the Seefra system.

Sigh, I'm such a geek...

Re:That's Life

[Marvelicious]

Just don't let Hollywood get ahold of this. Anyone say Armageddon 2!

Re:That's Life

[Dabido]

The New All Star Surviver!

Which star will be NEXT to be voted out of the Galaxy?

My Dog ate my sig.

Re:That's Life

[ShadowXOmega]

I think is the stellar entity WAN-TO, atacking his siblings/sons, or may be using a star as a decoy.
anyone readed:
("THE WORLD AT THE END OF TIME"; 1990)
FREDRIK POHL
Sorry for the link, but i dont finded it in english.
http://www.dreamers.com/libroscf/nova049.html

Outcast Star

[lecithin]

"We're tempted to call it the outcast star because it was forcefully tossed from its home."

Instead they are going to call it a galaxy challenged star.

Re:Outcast Star

[iroll]

I read this as Outlaw Star. Sad thing is I don't watch that much TV...

Re:Outcast Star

[lucabrasi999]

Instead they are going to call it a galaxy challenged star.

The Mayor Star of the Milky Way decided to form a committee to review the causes of "Outcast Star Syndrome". That committee, which will be composed of various leaders in the Star Community, along with interested Asteroids, Planets and Comets, will interview other Stars that have, through no fault of their own, also been cast out of the galaxy.

In six months, the Committee will issue a report that includes recommendations on how we can prevent Outcast Star Syndrome along with a 12 step program to re-integrate former Outcast Starts into the entire Milky Way community, with the hopes that they will become productive members of the community again.

Re:Outcast Star

[essreenim]

"We're tempted to call it the outcast star because it was forcefully tossed from its home."

...The star, catalogued as SDSS J090745.0+24507,

Scientist A: I know, lets call it the Outcast Star!

Scientist B: Nooogh, weeer not going to be doing that

Re:Outcast Star

[jmanforever]

If they are going to name it an outcast star, then shouldn't they call it André-3000?

Oh... that's OutKast. nevermind.

Re:Outcast Star

[Anonymous Coward]

Ok. I'm risking redundancy and/or offtopic here...

I vote they call the star "Fiorina".

http://money.cnn.com/2005/02/09/technology/hp_fior ina/index.htm :P

Re:Outcast Star

[operagost]

In other news, MoveON.org blames the "Outcast Star syndrome" on white Christian conservative rednecks.

Re:Outcast Star

[iamacat]

I miss Hitchhikers guide to galaxy. I am sure Douglas Adams would have an excellent explanation on exactly why the miserable species in that star system were expelled and what kind of comments they are hearing on the radio as they are zooming away.

Although maybe they are just trying to start a restaurant at the end of the universe.

Re:Outcast Star

[Anonymous Coward]

Do you understand humor?

Re:Outcast Star

[TommydCat]

Explaination's easy:
It's an Brockian Ultra-Cricket shot gone awry, of course!

Re:Outcast Star

[Anonymous Coward]

AMEN! You really tweaked the liberals with that one.

Coupla other points to be made.

Jesus wanted us to invade Iraq. If He didn't, why did he tell Bush that He did?

The earth WAS created in 7 days, but days longer back then? That explains how Noah lived to be 900 years old. Oops, wait, that would mean that he lived shorter according to our time. Never mind.

Re:Outcast Star

[Short Circuit]

I hope they add it to Celestia. Watching an object three times the size of the sun move across an accurate star field would be fascinating.

1.5 million miles per hour!!

[Anonymous Coward]

That's incredible.

I just wonder why the star and the planets are not torn apart by such huge speeds?

Re:1.5 million miles per hour!!

[IceAgeComing]

If everything around it is also moving that fast and in the same direction, then from the star's frame of reference, it's standing still.

Re:1.5 million miles per hour!!

[Anonymous Coward]

As if there are any planets at the core..

But as to your question about the star, I would think that the acceleration was not catastrophic within the gravitational reference frame.

There will be effects however, considering the velocity I would expect relativistic phenomena.

Re:1.5 million miles per hour!!

[witte]

It's relative speed to us (eg. the sun, or any other mass).
In the void of space this has no consequences for the mass that is speeding. (Until it collides with something that has a different speed.)

Abruptly increasing acceleration could rip it apart though, but that's another story.

Re:1.5 million miles per hour!!

[juangonzo]

They aren't torn apart for multiple reasons. One of them is that there is nothing for them to hit that will tear them apart. Going millions of mph is different in a vacuum than it is in the earth's atmosphere. To get more complex, to the star it's not moving, the rest of the galaxy is. To understand more of what I'm talking about read about the reference frame in any basics physics book.

Re:1.5 million miles per hour!!

[Tim C]

Torn apart by what? If it's not accelerating, and it's not undergoing frictional drag passing through a fluid or gas cloud, etc, why would it be torn apart? There's no force acting on it to tear it apart.

(Also, what planets? I did RTFA, and didn't see any mention of planets...)

Re:1.5 million miles per hour!!

[merlin_jim]

I just wonder why the star and the planets are not torn apart by such huge speeds?

a) we're not sure it has planets.

b) it's not velocity that kills, it's acceleration.

c) this acceleration can only be explained by current theory if it was a gravitational acceleration.

d) gravitational acceleration acts on all elements of an object equally, meaning that there was no force from the acceleration itself acting to tear the object apart. Just like when you're in freefall, you don't feel gravity acting on you.

Now TIDAL gravity can tear objects apart, but since the gravitationally assisted acceleration likely happened in the galactic core, the tides were probably pretty gentle... the tidal force at a black hole's horizon can be expressed as a function of mass over surface area; the bigger the hole, the less the tides.

Re:1.5 million miles per hour!!

[Chess_the_cat]

If everything around it is also moving that fast and in the same direction, then from the star's frame of reference, it's standing still.

But that's just it. Everything else is moving in the opposite direction.

Re:1.5 million miles per hour!!

[Anonymous Coward]

Wow, how insightful and original. Now check google/wikipedia for the Twin-Paradoxon and come again.

Re:1.5 million miles per hour!!

[Anonymous Coward]

Exactly. My first thought was what life would be like if Earth was arround a star like this. The only difference would be that early stargazers would eventually notice the changes in the constellations and that one part of the night sky is always much darker. This would probably result is some really interesting theories on the nature of the universe, not to mention the potential for a very lonely civilization.

Sounds like a good setting for a story actually...

Re:1.5 million miles per hour!!

[Anonymous Coward]

Wow, how insightful and original. Now check google/wikipedia for the The speed of light and come again.

Re:1.5 million miles per hour!!

[essreenim]

Exactly, although conceivably, the star has had a great deal of its mass stripped away by the event in question. The only predictable change would be due to gravitation from the black hole and the resultant cling-shot of acceleration afterwards. An interesting point though. That star is / was ( we are observing history - the star would have been very far away and is by now much much further away) in a different time frame. From the point of view of an observer at the outcast star, they are actually moving away from the galaxy at a much slower rate. Consequently, if any sentient observer were at that star, they are much further away from the galaxy than they might intuitively think they are..Ahhh relativity..

Re:1.5 million miles per hour!!

[Anonymous Coward]

Yes, however that doesn't answer his question.
I mean, the same goes for any moving object, even on earth.

It has more to do with collisions (which includes friction) and acceleration. Or in this case, the lack of those.

Re:1.5 million miles per hour!!

[Anonymous Coward]

d) gravitational acceleration acts on all elements of an object equally, meaning that there was no force from the acceleration itself acting to tear the object apart. Just like when you're in freefall, you don't feel gravity acting on you.

That's not entirely true. The force excerted by gravity goes as 1/r^2, where r is the distance between both masses.

If you have for example two large m1 and m2 each attached one end of a very long pole in a gravitational field caused by another mass M, the mass nearest to the M would experience a slightly stronger force than the other one. So that could, in theory, break the pole.

Re:1.5 million miles per hour!!

[Anonymous Coward]

Wow, how insightful and original. Now check google/wikipedia for the "Being an Ass" and come again.

Re:1.5 million miles per hour!!

[Dana P'Simer]

First, there is no indication that they have any evidience that the star has planets. Second, how exactly would mere velocity tear the start apart? I would not be suprised if, in the star's distant past, when it had it's close encounter with the super massive black hole at the center of the galaxy that some significant tidal forces were not placed on the star's contents. However, it appears that the star is stable, for the moment, ( moments in stellar lifetimes take millions of years ). The mere fact that the star is moving fast is not enough to tear it apart, there would have to be some other gravitational or kinetic forces at work. Do you realize that,

simply owing to the earth's rotation, you are, at this moment, moving at a rate of approximately 1000 mph? Probably less since you are probably not at the equator.

Also, Due to the earth's orbit around the sun, were are traveling at approximately 67000mph.

According to findings of COBE, our galaxy is traveling at 300 k/s or about 1.34 million mph.

Why aren't you torn apart?

Re:1.5 million miles per hour!!

[imuffin]

But it's not. From TFA: By measuring its line-of-sight velocity, it suggests that the star is moving almost directly away from the galactic center. "It's like standing curbside watching a baseball fly out of the park," said Brown.

So everything around it isn't moving at the same speed; it's moving 1.5 million MPH away from the center of the galaxy.

---
watch funny commercials

Re:1.5 million miles per hour!!

[StalinsNotDead]

Now check google/wikipedia for the "Being an Ass" and come again.

I did. It says:

No page with that title exists
You can create an article with this title or put up a request for it.

Re:1.5 million miles per hour!!

[merlin_jim]

That's not entirely true. The force excerted by gravity goes as 1/r^2, where r is the distance between both masses.

If you have for example two large m1 and m2 each attached one end of a very long pole in a gravitational field caused by another mass M, the mass nearest to the M would experience a slightly stronger force than the other one. So that could, in theory, break the pole.

What you're talking about is tidal gravity. And tidal gravity is exactly what caused one star of a companion to be accelerated away while the other one was captured into an orbit.

On the scale of the objects themselves, though, the tides were probably extremely gentle. AFAIK companion stars are generally light-months apart. Even if this star was a planetary system, it's nearest planets are probably only a few light-minutes away...

Re:1.5 million miles per hour!!

[CmdrGravy]

There was a book about almost exactly this, the only difference being the agency causing the stars acceleration was an alien species who lived in stars and the fact that they were constantly accelerating the Earth until it was travelling so fast the rest of the Universe had disappeared to a tiny dot in the sky.

It did kind of emphasise the ultimate pointlessness of a civilization which was doomed to death by the eventual destruction of the sun and which was unable to travel anywhere outside the solar system or indeed interact with the rest of the universe at all.

Re:1.5 million miles per hour!!

[j1bb3rj4bb3r]

Abruptly increasing acceleration could rip it apart though, but that's another story.

... or abruptly decreasing acceleration for that matter... it's called jerk.
When you fall off a tall building and splat on the ground, it's not the change in speed (velocity) of the impact, nor is it the change in velocity (acceleration), but the change in acceleration (jerk) that kills you.
*sigh*, it's always the jerk that kills you.

Re:1.5 million miles per hour!!

[Freexe]

http://en.wikipedia.org/wiki/Being_an_Ass so i did!

Re:1.5 million miles per hour!!

[j1bb3rj4bb3r]

b) it's not velocity that kills, it's acceleration.

huh... I just posted something about this to another comment...
that's not actually correct... it's not acceleration that kills, it's jerk (change in acceleration)

Re:1.5 million miles per hour!!

[Freexe]

its been removed already!

those mods are always ruining my fun :(

Re:1.5 million miles per hour!!

[Anonymous Coward]

And how is this is relevant to GGPs point?

Re:1.5 million miles per hour!!

[AndroidCat]

There will be effects however, considering the velocity I would expect relativistic phenomena.

Even more if you stand up and hold out your arms! (But they probably have a sign up to keep your arms and legs inside your reference frame at all times.)

Re:1.5 million miles per hour!!

[Anonymous Coward]

One small consolation...the time dilation caused by such a massive velocity would pretty much insure that Earth and its people would outlive the rest of the universe...

Re:1.5 million miles per hour!!

[LurkerXXX]

Really? I bet if we put you in a rocket, and had it accelerate and the acceleration built up very very very slowly, you would still turn to jelly when the acceleration finally hit 20 G's.

Re:1.5 million miles per hour!!

[witte]

Why aren't you torn apart?

Lions only eat Christians ?

Re:1.5 million miles per hour!!

[Anonymous Coward]

ugh.. stop the ride, i'm feeling dizzy!

Re:1.5 million miles per hour!!

[Holi]

Ahhh, thank you, I have been wondering what my next nasty torture should be for those pesky secret agents always crawling around my lab.

Bwaaa Haaaahaaahaaahahahah.

Re:1.5 million miles per hour!!

[merlin_jim]

"jerk" or change in acceleration kills because it's generally an order of magnitude or two greater than the final acceleration. But it's still the acceleration that kills you.

sudden changes in acceleration have other effects that can kill, especially w.r.t. safety harnesses and whatnot, because those kinds of systems generally store potential energy in tension systems in order to help our fragile organic selves to deal with the acceleration best; when the vector direction of acceleration changes, this potential energy is released, and at least some part of it will reinforce the new acceleration temporarily.

Of course neither of these kinds of acceleration-effect magnifying effects applies to a planetary system undergoing only inertial accelerations; an object undergoing gravitational acceleration experiences the change of inertia at every point in its mass, and gravitational acceleration changes smoothly and continously as you move through spacetime.

Re:1.5 million miles per hour!!

[WhiplashII]

Yes, but that would make you a jerk, so the poster is correct!

Seriously though, what kills you is the difference in acceleration of the top and bottom - which is what the previous person said.

Re:1.5 million miles per hour!!

[Anonymous Coward]

>> Really? I bet if we put you in a rocket, and had it accelerate and the acceleration built up very very very slowly, you would still turn to jelly when the acceleration finally hit 20 G's.

In that case, you're still talking about a change in acceleration, not a constant acceleration.

The point is, when an acceleration on one part of your body overwhelms the cohesive force of chemical bonds, some parts of your body will no longer cooperate with other parts and this disrupts the process you like to call "your life." :)

Re:1.5 million miles per hour!!

[Anonymous Coward]

its been removed already!

It's back again!

Re:1.5 million miles per hour!!

[Freexe]

that guy really is an arse!

Re:1.5 million miles per hour!!

[IceAgeComing]

You're right; I wasn't clear in my original post. I meant "everything local to the star". I was grooving on the idea that life could still exist in the solar system created by this star, provided the planet rotating around the star wouldn't get bombarded by stuff flying into the solar system. If the space between galaxies isn't littered with matter, then this seems a possibility.

Re:1.5 million miles per hour!!

[Anonymous Coward]

For those with more brains and/or less work than I,

what is the cumulative vector velocity of a human being at rest at the equator?

i'd love to be able to use it as additional proof of my next "work" trip...

Re:1.5 million miles per hour!!

[Shakrai]

There was a book about almost exactly this

Do you remember the title? It sounds like interesting reading.

It did kind of emphasise the ultimate pointlessness of a civilization which was doomed to death by the eventual destruction of the sun

Four and a half billion years isn't enough time to come up with technology to move the sun back towards the rest of the universe or figure out the light-speed problem??

Re:1.5 million miles per hour!!

[LurkerXXX]

Well, you can't get to once rate of accelleration from another rate with out changing it. Duh. That's why I said slowly, so there would be no sudden change.

The point is, it doesn't matter how quickly you got to that 20 G's of accelleration,or if you had always been at it.

Imagine you are a human somehow born in a rocket accellerating at a constant 20 G's. No change in accelleration. You've always been accelerating at 20 G's, and always will. Ok? No change in acceleration. 20, period. It's now 10 seconds after you've been born. Your blood is now starting to accumulate in the 'lowest' parts of your body. Why? Your human heart cannot pump blood against a force of 20 G's. Your brain starts running out of oxygen. In a few seconds you pass out. Then in another minute or so, you die. All this time you have been going at a constant acceleration of 20 G's, and all parts of your body are under exactly that exact same acceleration. You are however, quite dead. Acceleration alone *can* kill. No change in acceleration is needed.

Re:1.5 million miles per hour!!

[MyLongNickName]

Depends on your reference frame.

Re:1.5 million miles per hour!!

[LurkerXXX]

Seriously though, yes, that can kill you, but acceleration alone can as well. See the other reply in this thread. No change or difference in accelerations is needed to kill you.

Re:1.5 million miles per hour!!

[j1bb3rj4bb3r]

I believe we should deign to this study for the definitive effects of acceleration.

:)

Re:1.5 million miles per hour!!

[Anonymous Coward]

> The point is, it doesn't matter how quickly you got to that 20 G's of accelleration,or if you had always been at it.
> Imagine you are a human somehow born in a rocket accellerating at a constant 20 G's. No change in accelleration

Well, if you're going to work from impossible premises, then there's no point discussing it.

If you're alive while you're accelerating at a constant rate, then only a *change* in acceleration will kill you. Capisce?

Re:1.5 million miles per hour!!

[Anonymous Coward]

> Seriously though, yes, that can kill you, but acceleration alone can as well. See the other reply in this thread. No change or difference in accelerations is needed to kill you.

Nope. If you can survive in a given acceleration (hint: the gravity well you live in) then only a change in acceleration will kill you.

Re:1.5 million miles per hour!!

[WhiplashII]

I agree with what you said, and I agree with what I said - the difference is in the interpretation. You talked about blood pooling, for example. Blood pools because if your body is being accelerated and your blood isn't, it "resists" the change in velocity. However if your blood is accelerated also there is no problem.

As an example, place an unlucky astronaut in space a few parsecs from an ultramassive black hole, such that he is accelerating at 10000 m/ss. He will experience weightlessness - and be fine (until tidal forces tear him apart, that is).

Re:1.5 million miles per hour!!

[Anonymous Coward]

Nope. The discussion wasn't talking about where you can normally survivae at a given accelleraion. It was if acceleration alone could kill you. It can. Of course to be at a different accelleration you will have to change them, but the change itself is not necessarily what kills.

Re:1.5 million miles per hour!!

[Anonymous Coward]

You can't get to the 2nd accelleration without making a change in acceleration, so there is always going to be a change. The question is if the change is what kills, or if the 2nd acceleration rate can kill in and of itself once you reach it. If you aren't going to understand that concept, you are right, there is no point discussing it.

Re:1.5 million miles per hour!!

[meringuoid]

what is the cumulative vector velocity of a human being at rest at the equator? Depends on what you consider to be stationary: all the stars and galaxies are also moving, remember. Relative to a frame of reference in which the cosmic background radiation is broadly isotropic, we're moving at about 600 km/s.

Re:1.5 million miles per hour!!

[Anonymous Coward]

> The question is if the change is what kills, or if the 2nd acceleration rate can kill in and of itself once you reach it. If you aren't going to understand that concept, you are right, there is no point discussing it.

What's to understand? The claim was that "acceleration alone can kill you." But that assumes you are alive in the first place, which in 20g is not possible, so it's irrelevant whether "the 2nd rate of acceleration can kill in and of itself."

A 20g gravity field is not survivable whether you go there from Earth (possible) or are born there (impossible). Please give me a physically possible scenario in which a constant acceleration can kill you.

Re:1.5 million miles per hour!!

[Anonymous Coward]

He will experience weightlessness - and be fine (until tidal forces tear him apart, that is).

Actually, the tidal forces from such an ultramassive black hole will be negligible...the more massive the black hole, the gentler the gravity gradient. So, the astronaut will be weightless, and fine. On a side note, since he will be accelerated to a very high velocity while falling into this black hole, and since relativity will dilate his time considerably, from his point of view, would he ever actually get to the black hole?

Re:1.5 million miles per hour!!

[zod1025]

When you fall off a building, just before hitting the ground your speed is X and just after hitting the ground your speed is 0. This is a change in velocity (ie, an acceleration). It is this large acceleration (something typically talked about as G-forces) that kills you. More specifically, the change in velocity is experienced on one side of the body sooner than the rear, causing fatal body deformations (ie, the "Splat"). If you could magically experience the change in velocity at all points of your body at the same time, then you would not "Splat"... but the stopping force is applied unevenly, causing this "jerk". I had never heard this referred to as "jerk" before, but that makes sense now.

Re:1.5 million miles per hour!!

[Anonymous Coward]

Yes he would from his point of view, but not to an observer at a safe distance away. In fact, if the astronaut were to somehow pull away just before the event horizon and get back to his (incredibly well built) spaceship he would find that hundreds/thousands/millions/billions of years of ship time have passed while he experienced only a few minutes/hours.

Re:1.5 million miles per hour!!

[LurkerXXX]

Right on the tidel forces.

As for his body being accelerated and his blood isn't... That's only the case in as much as right now your body is trying to accelerate at 9.8 m/s/s toward the center of the earth. Your bone structure and muscles lets you resist it. Your blood is also trying to accelerate towards the center of the earth at the same rate. Your arteries and veins and your heart let you resist that as well.

Your body and blood aren't accelerating at different rates. They both deal with the same acceleration in the same way, with it acting as 'weight'. The problem with weight/acceleration is that your body was designed to handle only so much of it.

Now let's kick it up a notch. blood pooling...

Imagine a test pilot in a centrafuge machine. It takes him up to 6 G's and holds him there for an hour. Just like he was on a planet with 6x earth's gravity.

His body is accelerating at 6 G's.
His blood is also accelerating at 6 G's (otherwise it would all leak out the back of his chair and that would be a 'bad thing' ;)

His blood resists accelerating as you say, but so does his body (Bodies at rest tend to stay at rest tend to stay at rest, bodies in motion tend to stay in motion and all that). Nevertheless, the back of his chair is causing the lot of them to accellerate at 6 G's.

His heart, however is now trying to pump blood that 'weighs' 6x as much. The heart can't pump the heavier blood as easily or 'high' (relatively) as it could normally. His veins can't constrict as much as they normally would to force blood back into the right areas of the body, because the blood is pushing against them with much greater force. The veins also have valves to prevent blood from flowing back the wrong way, but these may give way under the additional pressure.

The blood is not accelerating at a different rate from the body, it's still in his veins and artieris, and so still in his body. His body is being accellerating at 6 G's and the blood, being trapped inside, is going along for the ride. But it acts as a much heavier fluid. So it starts to pool in the lower extremeties since it can't be pumped efficiently. Depending on how strong his heart is (and resilient his veins are), he might be able to handle 6 G's for a good long while. But if they aren't in quite as good of shape he might not be able to pump the blood well enough and might black out after a few seconds or minutes.

Once again the blood isn't accelerating at a different rate than the body (both are resisting being accelerated), anymore than your blood and body accelerate at different speeds on earth, it just has a higher 'weight' then the body was structurally designed to pump.

The next stage is to crank up the centrifuge chair/other-planet to 1000g's density. 1000 G's. Now the test pilot's ribs are trying to hold up themselves and the muscles etc attached to them. But they weight 1000x as much. The bones werent' constructed to hold such a high weight, so they snap. The 'body' isn't accelerating at a different rate than the... 'body', but it breaks down because it wasn't designed for such mechanical forces. Everything is being accelerated (and trying to resist it). Everything is accelerating at the same rate. It just can't handle the rate.

Re:1.5 million miles per hour!!

[Anonymous Coward]

1000 G's.

Human body + 1000 Gs = chunky salsa

Re:1.5 million miles per hour!!

[Anonymous Coward]

Put someone in one of those centrifuge machines you see astronauts train in. They hand handle something like 5-6 G's for quite a few minutes. Some with not so great cardio systems will black out relatively quickly. It wont' kill you doing that for a while. Now trap someone in it for a couple days. Their heart will almost certainly give out trying to pump super heavy blood for that long of a period of time.

Re:1.5 million miles per hour!!

[CmdrGravy]

I think the Earthlings were too interested in fighting each other and working out how to live underground to anything constructive.

Someone else later in this thread has posted the title of the book, I think it is by Frederick Pohl and is called "The World At The End Of Time"

Re:1.5 million miles per hour!!

[mr_z_beeblebrox]

Second, how exactly would mere velocity tear the start apart?

Acceleration past the rated speed, or rapid acceleration after sustaining heavy damage (Klingon attack). This is why during peaceful times the Enterprise can easily pass warp 9, but after sustaining a klingon photon torpedo attack (with no casualties mind you) warp four could easily "tear her apart".
If you spent a little less time studying and a little more time in front of the tube...you would know stuff like this.

Re:1.5 million miles per hour!!

[pclminion]

Yes, but that would make you a jerk, so the poster is correct!

In case people don't get this joke... The rate of change of acceleration is technically called "jerk."

Re:1.5 million miles per hour!!

[pclminion]

it's not velocity that kills, it's acceleration.

Acceleration doesn't kill. You could accelerate at 1 billion G's, and so long as every part of your body was accelerating at the same rate, you would feel nothing.

What kills you is spatial force gradients. Suppose you skydive without a parachute. You smack into the ground. You die, not because you experience a gigantic acceleration but because the acceleration is only applied to the body surfaces which contacted the ground first. That force is then transmitted through your body, and because your body is not infinitely rigid, it deforms.

You got the answer kind of right when you said that "gravitational acceleration acts on all elements of an object equally," but in truth there is nothing special about gravity compared to other forces. It is the fact that the acceleration is constant across an object which is the real key here. In practice, only gravitational forces have this property but it isn't something intrinsic to gravity, per se.

Re:1.5 million miles per hour!!

[Anonymous Coward]

keep your arms and legs inside your reference frame at all times

Generally that's a good idea even when perfectly still.

Re:1.5 million miles per hour!!

[Anonymous Coward]

It's a Frederick Pohl novel. I don't remember the title off hand...

Re:1.5 million miles per hour!!

[lazy genes]

I think they have made a mistake.The fabric of space-time should not allow it.At that speed it would be spiraling.It would not have survived the traffic near the blackhole.Imagine a universe with only two galaxies.They would move in a figure 8 pattern. space-time would shape the galaxies into a disk when they are close to each other .When they are at their farthest positions they would look like footballs.Spiral galaxies dont shoot jets from their poles because the fabric is loose.

Re:1.5 million miles per hour!!

[Dana P'Simer]

But you are forgetting that we are talking about sublight speed. The damage done by a photon torpedo can easily disrupt the fragile warp fields. Warp speeds are created by sucessive warp shells like those nesting dolls. To reach warp 9 you need 9 nested warp shells.

I guess I spend more time infront of the tube than you :P

Re:1.5 million miles per hour!!

[Anonymous Coward]

Who modded this up 'informative'? It's plain wrong.

Just the last sentence "everything is accelerating at the same rate. It just can't handle the rate" is proof that LurkerXXX doesn't understand the physics of acceleration. Instead of saying, "oh, I see," he just keeps arguing out of his ass.

In the case of the centrifuge, if the body were accelerating *as a whole* at the same rate, it would feel no effects; it's the fact that the body is getting squashed against the centrifuge that it "can't handle."

Re:1.5 million miles per hour!!

[mr_z_beeblebrox]

Warp speeds are created by sucessive warp shells like those nesting dolls

That is true. I bow to your knowledge my pointy eared friend.

Re:1.5 million miles per hour!!

[Anonymous Coward]

> if the astronaut were to somehow pull away just before the event horizon and get back to his (incredibly well built) spaceship he would find that hundreds/thousands/millions/billions of years of ship time have passed while he experienced only a few minutes/hours.

Have you read Fredrik Pohl's 'Gateway'? He uses this idea to an astonishing dramatic effect.

Re:1.5 million miles per hour!!

[Anonymous Coward]

> Human body + 1000 Gs = chunky salsa

Not exactly-- only if it's not uniformly accelerated.

You could fall to the surface of a 20G planet, or a 100G planet, or a 1000G planet, it doesn't matter. As long as you're in free fall, you're fine in that rate of acceleration until you hit something.

You could even be "born into" a 20G acceleration. As long as your mother is giving birth to you in free fall, you'd both be just fine at 20G. For a short while, anyway.

Re:1.5 million miles per hour!!

[AndroidCat]

"There goes my left arm. How am I going to operate my digital watch now?"

It's like matrix all over again...

[FirienFirien]

A bundle of stars spinning round at high speed, flinging out another star to get extra speed!

a giant ball of flame at a million miles an hour

[essreenim]

galactic pin ball here we come!!

Imagine if that happened to earth

[Anonymous Coward]

We would all be dead before we even realized what happened, 1.5 million miles per hour? jesus christ that is fast

In other news

[Anonymous Coward]

speeding along at over 1.5 million miles per hour

In other news, Carly Fiorina left H-P at a speed of over 1.6 million miles per hour.

Yep.

[inertia187]

Just like my screen saver predicted.

1.5 Million MPH...

[sidepocket]

relative to what?

It still amazes me how they can measure that kind of stuff.

Re:1.5 Million MPH...

[Rakshasa Taisab]

Look up the topic of Doppler shift. And it's relative to the galaxy, isn't that pretty obvious from the context?

Re:1.5 Million MPH...

[maird]

I don't actually know how they measured it (and I'm not an astrophysicist and don't offer this as opinion, let alone fact) but 1.5 million miles per hour probably creates a significant doppler shift. The spectra of stars shows distinct bands that correspond with the absorption of photons at specific wavelengths. The reason the absorption is at specific, discrete wavelengths is that electrons in specific elements (e.g. Hydrogen, Helium, etc) absorb at specific wavelengths. The distance between absorption lines for different elements is fixed. For example, say Helium absorbs at some wavelength x and Hydrogen at some wavelength y. The difference between x and y is a constant (even under a doppler shift). So, if you see two absorption lines and they are x - y apart then one is the Hydrogen and one the Helium. This is overly simplified but the principle is the same (it just involves more than two lines). You can then tell how much doppler shift because you know what wavelength they should appear at and see what wavelength they actually appear at. Doppler shift is directly proportional to speed (I hope that's accurate). So, knowing the doppler shift you know the speed relative to the point of observation. Presumably you can work out the speed of the earth relative to some object by measuring the relationship between doppler shift from that body and the doppler shift from various other celestial bodies. Or, maybe they had a very long tape measure, a very powerful radar, or a very powerful laser or just guessed ;-)

Re:1.5 Million MPH...

[mikael]

It still amazes me how they can measure that kind of stuff.

That's easy. All you need to is take photographs of the sky over a sequence of time. Anything that moves (asteroids, comets, planets, and now stars) will appear at a slightly different location in each frame. With enough photographs, you can deduce the motion of the object.

The hard part is knowing where and when to aim the telescope.

All kinds of morons on Slashdot...

[Anonymous Coward]

Are you an idiot?

We wouldn't notice anything. Speed doesn't kill. Do you realize how fast we're going around the sun?

Re:All kinds of morons on Slashdot...

[Hyecee]

I think he might have meant if we were to be run over by a random sun moving at that speed. Could be wrong, though.

Re:All kinds of morons on Slashdot...

[Anonymous Coward]

Not anywhere near 1.5 million miles per hour.

By the way, nice subject, it really lets people know what to expect from your post.

Re:All kinds of morons on Slashdot...

[mirko]

(150 millions kilometers radius) * 2 * pi / ~31 millio9ns seconds = 30km/s (~20 mps)

Re:All kinds of morons on Slashdot...

[Skye16]

No kidding. We worry about asteroids; imagine catching a star in the face.

Re:All kinds of morons on Slashdot...

[Dana P'Simer]

Your math is flawed. The earth has a circumference of approximately 24000 miles at the equator. The earth rotates once in 24 miles. Therefore, objects at the equator are moving at approximately 1000 mph. I am in Georgia near the 34th parallel. That means I am probably traveling at somewhere around 700 - 800 mph. Just a quick guess but considerably closer than yours.

Re:All kinds of morons on Slashdot...

[Anonymous Coward]

The truth?

We wouldn't even notice the earth moving that fast.

It would feel the same, except we'd all freeze to death.

Re:All kinds of morons on Slashdot...

[mirko]

I approxed the number of second/year to 31 millions so my 30km/s is already approx but by a low factor, now, your 750 mph doesn't even add half a km/s to my "flawed math" so please...

Re:All kinds of morons on Slashdot...

[Hyecee]

Yeah. At that point, the star would probably just be catching us in the face.

Re:All kinds of morons on Slashdot...

['nother poster]

Um, excuse me, but as anyone can tell you, the universe revolves around ME! Therefore the sun is going around me really fast, not the other way around.

Sheesh.

Vendela, Kate, Tyra, feed me more peeled grapes while you finish my massage.

Re:All kinds of morons on Slashdot...

[Dana P'Simer]

LOL, thought you were approximating the speed due to rotation not orbit... Sorry.

Re:All kinds of morons on Slashdot...

[Anonymous Coward]

>> Your math is flawed. The earth has a circumference of approximately 24000 miles at the equator. The earth rotates once in 24 miles. Therefore, objects at the equator are moving at approximately 1000 mph.

And since the grandparent post questioned how fast we're moving *around the sun* and not how fast we're moving around the center of the earth, you've done completely the wrong calculation.

That's also ignoring your meaningless "earth rotates once in 24 miles" comment, assuming it's a typo.

Re:All kinds of morons on Slashdot...

[Anonymous Coward]

Do you realize how fast we're going...?

[cue music]

Just remember that you're standing on a planet that's evolving
And revolving at nine thousand miles an hour.
It's orbiting at nineteen miles a second, so it's reckoned,
'Round the sun that is the source of all our power.

Now the sun, and you and me, and all the stars that we can see,
Are moving at a million miles a day,
In the outer spiral arm, at fourteen thousand miles an hour,
Of a galaxy we call the Milky Way.

Re:All kinds of morons on Slashdot...

[ArsenneLupin]

Speed doesn't kill.

Just don't tell that a traffic cop...

Re:All kinds of morons on Slashdot...

[Pfhorrest]

All togther now!

It's a great big universe, and we're all really puny
We're just tiny little specks about the size of Mickey Rooney
It's all big and black and inky,
And we're just small and dinky
It's a big universe,
And we're not!

Fling out of the galaxy

[falser]

Ok, now how do we apply this knowledge to do the same to Microsoft/Paris Hilton/Terrel Owens/Celine Dion.... ?

Re:Fling out of the galaxy

[Rude Turnip]

Between Microsoft and Paris Hilton alone, there is so much suction I'm surprised the rest of us haven't been flung into space.

Re:Fling out of the galaxy

[geoffrobinson]

What do you have against T.O.?

Re:Fling out of the galaxy

[witte]

Well, you throw 'em into near-orbit around a black hole, so they get slingshot out of the galaxy.

In your example, succes or failure of this method would be irrelevant, though... Any outcome would be acceptable :)

Re:Fling out of the galaxy

[Anonymous Coward]

Nothing.

However puke-boy McNabb is another story. He's like Stan from South Park.

"Oh no, the Patriots!"

Bleeeargh

Re:Fling out of the galaxy

[Anonymous Coward]

> Between Microsoft and Paris Hilton alone, there is so much suction I'm surprised the rest of us haven't been flung into space.

"Now GET THE HELL OUT OF OUR GALAXY! Both of ya!"
- Captain John Sheridan, B5.

Re:Fling out of the galaxy

[Anonymous Coward]

I'll take Celine Dion.

Outcast Star?!

[flumps]

"We're tempted to call it the outcast star because it was forcefully tossed from its home."

I wondered where all those Jedi had gone to...

Re:Outcast Star?!

[pklong]

No wonder they couldn't find the star in the Jedi archives

hmm.

[xsyberpunk]

i'm still waiting to read about how they forgot to clean their telescope and calibrate their equipment.

Wish Upon A Star...

[FIGJAM]

Starlight, star bright, first-of-its-kind star I see tonight, I wish I may, I wish I might, get laid tonight.

Re:Wish Upon A Star...

[disserto]

You might also want to wish that you're not as speedy as the star.

Re:Wish Upon A Star...

[Anonymous Coward]

If there's any group more sexless than Linux users it's gotta be astronomers.

Re:Wish Upon A Star...

[Anonymous Coward]

Request granted. Come over later tonight.

My cock is waiting for you.

Speed is relative

[Hoi Polloi]

What are they measuring the star's speed against? The center of our galaxy? The earth?

Re:Speed is relative

[Anonymous Coward]

The movement of the other stars that are 'relative' to its position. The other stars that are in our galaxy.

Re:Speed is relative

[grahamsz]

Presumably if it's leaving our galaxy then that'd be the normal way to look at it.

Alternatively maybe it's staying still and we are being flung away from it at 1.5M mph.

Re:Speed is relative

[Anonymous Coward]

relative to an arbitracy point in space that is moving 1.5M mph in the other direction relative to the star.

Re:Speed is relative

[FirienFirien]

It'll be measured relative to the galactic hub - measuring the speed relative to the earth is irrelevant, since you don't look out of your car and think that cars coming the other way are going at twice the speed limit, instead it's relative to the frame of reference of the ground {hub}.

Then again, with a speed that high, the speed of the earth/sun becomes insignificant anyway (8.5 miles/s and 155 miles/s respectively)

Re:Speed is relative

[kentyman]

relative to an arbitracy point in space that is moving 1.5M mph in the other direction relative to the star.

That doesn't sound very arbitracy to me.

Re:Speed is relative

[jridley]

It's moving like hell compared to any large body in the galaxy, or the average.

I remember this story:
Professor: The temperature in this kind of reaction is about 3 million degrees.
Student: Is that Celcius or Kelvin?
Professor: It doesn't matter!

IOW, the difference between C and K at ~3m* is insignificant. In the same way, the speed of this star is practically the same from any point of reference near any star in the galaxy.

Re:Speed is relative

[sharkey]

Kevin Bacon?

Re:Speed is relative

[Anonymous Coward]

Measured vs the center of mass for the galaxy.

Re:Speed is relative

[Agent Orange]

All measurements of stellar velocities are not the stars true velocity - they are "radial" velocities. This is the geometric projection of the stars 3 dimensional velocity along the line of sight. Now, when you do this, everything is moving and many corrections must be made.

First, we correct for the rotation of the earth, and the movement of the earth around earth-moon barycentre. Then we correct for the earths movement around the sun. This is what is usually reported, and it is called the Heliocentric (i.e. centred on the sun) radial velocity.

Now the sun moves a little bit (about 20km/s) with respect to stars in our local neighbourhood, so we correct to this so-called "local standard of rest" or LSR.

From the LSR velocity, we can take out the movement of the sun aroudn the galactic centre, and put it in a galactocentric standard or rest, or GSR. This is done via the relation
v_GSR = v_LSR + 220*sin(l)*cos(b), since the sun has a circular velocity around the galactic centre of about 220km/s. l and b here are the galactic latitude and longitude, with (l=0,b=0) the galactic centre and l increasing counter-clockwise.

So, what we really care about, is the GSR velocity, from which we can tell whether the star is bound or not (i.e. is v_GSR > escape velocity).

There is a link to the actual article here (which has been submitted).

BUT! Don't forget, we measure only 1 component of the velocity (towards/away from us) - we really need all 3 (side-to-side as well) which are called "proper motions". So it could in fact, have higher a higher velocity.

HTH

Re:Speed is relative

[Agent Orange]

NOT TRUE!! The difference between the stars LSR and GSR velocities is similar from out point of view, because it's velocity vector points almost perpendicular to our motion around the galactic centre (see my other comment for more details about frames).

For observers 1/4 of the way around the galaxy in the disk at the same radius, it will be vastly different, since then the circular velocity aroudn the galactic centre is in the same dircection (roughly) as the star and so the difference between "LSR" and GSR frames will be significant.

Re:Speed is relative

[Anonymous Coward]

Exactly! Moreover, TFA has it completely wrong! (Imagine that happening on Slashdot.) The headline should have read: Hooligan Big-Ass Star Tosses Milky Way into the Hinterlands!

Re:Speed is relative

[tdubz]

They sent a state trooper up with a radar gun. Maybe that't why it is reported to be going so fast... The damn troopers always seem to overestimate speed.

Black + White reference

[Phil246]

Thinking about it makes me think about casting a fireball spell on black and white and flinging it at some poor villiagers.

i sure wouldnt want to be in the way of THAT fireball :D

Re:Black + White reference

[xxxJonBoyxxx]

Hell, this could be a D&D reference. I suppose the old maximum of 20d6 doesn't apply here, however.

Re:Black + White reference

[AndroidCat]

Ha! I made my saving throw and only take half damage!

Re:Black + White reference

[ultranova]

i sure wouldnt want to be in the way of THAT fireball :D

Don't worry, someone else is (second from the top, day 143).

Re:Black + White reference

[maotx]

I'm still waiting for them to release BW2

More than twice the speed of light?

[Anonymous Coward]

Don't think so. 1.5 million miles per hour is approximately 2.4 million km per hour or 670 km per second. Ah well, that differs only by a factor 1000.

Re:More than twice the speed of light?

[LSD-OBS]

I believe the article was talking about it moving twice the galaxy's escape velocity, not twice the speed of light.

Re:More than twice the speed of light?

[Anonymous Coward]

I'm quite sure the summary said 670 thousand kilometres per hour, but it seems they corrected it...

Re:More than twice the speed of light?

[Anonymous Coward]

Actually, that would still be 1/1600 the speed of light

Re:More than twice the speed of light?

[Anonymous Coward]

> I'm quite sure the summary said 670 thousand kilometres per hour, but it seems they corrected it...

Well, if you can keep straight the difference between km/h and km/s, you should be okay.

Why?

[computerme]

Why does that star hate America?

Re:Why?

[whitroth]

Because it's afraid Bush will find oil on one of its planets and invade it, obviously.

Re:Why?

[Anonymous Coward]

> Why does that star hate America?

Typical Hollywood liberal self-important "I'm a star" behavior!

Re:Why?

[Nqdiddles]

Why does it always have to be America? Can't it hate the French like everyone else?

Re:Why?

[Anonymous Coward]

Because it is sentient.

Re:Why?

[pizzaman100]

Another disgruntled Kerry supporter. Going to Canada is understandable, but leaving the galaxy?

Relative speeds

[FirienFirien]

A bit of googling pulled up:

Meteorites: 10ish miles per second, depending (yukon = 9.3)
Earth through space: 18.5 miles per second
Sun through space: around 155 miles per second

This thing is moving really quite scarily fast. The energy in that thing must be huge, since it's already 3 times the size of the sun.

Questions: what would the effects of the speed be? Would the galaxial dust clouds be dense enough to 'fan the flames'? How does something that gets accelerated to that speed stay together - or, how big was it before it shed all the mass that couldn't stay together!

There was a monty python song about this... *hums*

Re:Relative speeds

[Anonymous Coward]

"How does something that gets accelerated to that speed stay together - or, how big was it before it shed all the mass that couldn't stay together!
"

It doesn't. It will shed particles. It will probably make really cool nebula. Possible planetary creation as well.

Re:Relative speeds

[ZebadiahC]

Or maybe the Milky Way is moving away from the sun at 75 Million Miles/second and the sun is moving away from the galaxy at 75 Million Mps.

Intersting that there is no mention of any acceleration, just a constant velocity.

And why are we using Miles anyways?

Re:Relative speeds

[khallow]

It's had plenty of time to settle down. In fact, I wouldn't be surprised to find that it still had most of its mass. After all, the star is densest in its interior. Most of the mass probably is concentrated there. The near pass might have shed a portion of the near surface layers (due to tidal forces), but those would probably have been strewn all over the place and little would travel along the trajectory of the star.

As far as acceleration goes, tidal forces are what would potentially tear a star up. Those decrease as inverse of radius cubed (I don't recall how relativity changes things here). So it's possible that the star never experienced significant tidal forces.

Re:Relative speeds

[Anonymous Coward]

I blame global warming.

Re:Relative speeds

[FirienFirien]

You first comment is odd - the milky way the galaxy.

If you want to measure acceleration, you have to be able to check the speed accurately at two different times. Considering they just found this, and they'd have to find a measurable difference over a long enough time to detect acceleration at this considerable fraction of lightspeed, you might have to wait a while.

Miles are used because NASA still likes 'em. Miles (Vorkosigan) is used because he can get out of anywherefast.

Re:Relative speeds

[nizo]

Is it possible for a star flung like this to keep any planets it had, or would they most likely get sucked off by the black hole?

Re:Relative speeds

[Anonymous Coward]

> Is it possible for a star flung like this to keep any planets it had, or would they most likely get sucked off by the black hole?

Maybe, but it's *definitely* possible for a star flung out of Planet Hollywood to get sucked off by a black ho.

Re:Relative speeds

[b00le]

Is it possible for a star flung like this to keep any planets it had

I'd really like an answer to this one, as I've used the concept in a novel - I liked the idea of a race that could look up in the sky and see the whole galaxy. What kind of religion would they dream up. In truth I doubt a habitable environment could survive this kind of ride but I'd love to be proved wrong.

Re:Relative speeds

[EvilTwinSkippy]

Just remember that you're standing on a planet that's evolving,
And revolving at 900 miles per hour,
That's orbiting at 19 miles a second, so it's reckoned,
A sun that's the source of all our power.
The sun and you and me and all the stars that we can see,
Are moving at a million miles a day
In an outer spiral arm at 40,000 miles an hour,
Of a Galaxy we call the Milky Way.

Re:Relative speeds

[Viking Coder]

Come on! You gotta do the whole thing!

Just remember that you're standing on a planet that's evolving
And revolving at nine hundred miles an hour,
That's orbiting at nineteen miles a second, so it's reckoned,
A sun that is the source of all our power.
The sun and you and me and all the stars that we can see
Are moving at a million miles a day
In an outer spiral arm, at forty thousand miles an hour,
Of the galaxy we call the 'Milky Way'.

Our galaxy itself contains a hundred billion stars.
It's a hundred thousand light years side to side.
It bulges in the middle, sixteen thousand light years thick,
But out by us, it's just three thousand light years wide.
We're thirty thousand light years from galactic central point.
We go 'round every two hundred million years,
And our galaxy is only one of millions of billions
In this amazing and expanding universe.

The universe itself keeps on expanding and expanding
In all of the directions it can whizz
As fast as it can go, at the speed of light, you know,
Twelve million miles a minute, and that's the fastest speed there is.
So remember, when you're feeling very small and insecure,
How amazingly unlikely is your birth,
And pray that there's intelligent life somewhere up in space,
'Cause there's bugger all down here on Earth.

Re:Relative speeds

[Spackler]

You seem to be using "through space" as a non-relative term. If the sun is moving "through space" at 155 miles a second, how can earth be moving "through space" at only 18 miles a second. It that was the case we would be 16,000 miles farther from the sun since I started writing this email. 3 million miles more than when I woke up this morning and 180,795,888,000 miles since I was born.

Re:Relative speeds

[Anonymous Coward]

OK...here's an answer for you...

First, a star this close to the galactic core probably wouldn't have planets to lose anyway, and if it did, they are most probably incapable of suppporting life (there's quite a lot of hard radiation in the Core).

Second, assuming that this star does have a habitable, inhabited planet, the close passage to a gravity source this intense will almost certinly disrupt the planet's orbit. Even though the gravitational gradient from such a large black hole is quite gentle, the orbit will still be affected, most probably warping it into a more elliptical path around the star (which will probably be rather unpleasant).

Third, a slingshot-type approach such as the one we are contemplating will impart significant angular momentum (spin) to the star. Again, since we're dealing with such a gentle gradient, the star won't spin apart, but the spin will adversely affect the planet's rotation as tidal locking slowly takes effect. (Not sure just how much of an effect this would be, though...I'll leave more mathmetically adept readers to do the math.)

Re:Relative speeds

[vi-rocks]

Meteorites: 10ish miles per second, depending (yukon = 9.3) Relative to the Earth
Earth through space: 18.5 miles per second Relative to the Sun
Sun through space: around 155 miles per second Relative to the Galactic Centre

Re:Relative speeds

[b00le]

Thanks - that's roughly what I thought. It still leaves me a little room to manoeuvre. Maybe after the system is flung out of the galaxy, things could settle down enough to let evolution produce my people... not that anyone is ever going to be able to check.

Re:Relative speeds

[zsau]

While I can't see how these compare because the article gives speeds in miles per hour and kilometres per second, but you're giving them in miles per second, I can tell you that they must be wrong. Earth obviously travels through space about as fast as the Sun, in order to maintain its orbit around it.

Re:Relative speeds

[khallow]

I know a similar isolated system was described in "A Fire Upon the Deep" by Vernor Vinge though only part of the story took place there. The system happened to be naturally positioned between the Milky Way and the Magellan Clouds as I recall which gave it some mercantile advantages (speed of light was an issue only if you lived in the bad parts of the galaxy).

I've been considering ways to move an entire solar system (say to another galaxy). A star moving in the right direction with one or preferably more usable planets (even if those planets are in highly elliptical orbits) makes that job a whole lot easier. On the time scale of millions of years, radical shifts in orbits of planets should be easily achievable for a durable starfaring race.

Re:Relative speeds

[Anonymous Coward]

Although it's a brilliant summary of current cosmological theory, I've always thought the rhyme at the end of the second verse sucked.

Re:Relative speeds

[khallow]

Third, a slingshot-type approach such as the one we are contemplating will impart significant angular momentum (spin) to the star. Again, since we're dealing with such a gentle gradient, the star won't spin apart, but the spin will adversely affect the planet's rotation as tidal locking slowly takes effect. (Not sure just how much of an effect this would be, though...I'll leave more mathmetically adept readers to do the math.)

Actually, this isn't the scenario described in the article. The theory concerns binary systems where one of the partners is trapped by the black hole and the other is thrown out. The angular momentum (plus maybe a boost from the partner sliding down the gravity well) is converted to regular momentum.

Second, tidal locking wouldn't be significantly effected by a change in the star's spin. For example, the Sun spins faster than any of the planets (particularly Mercury). Instead, tidal locking comes from the star's tidal forces (which is significantly greater) acting on the planet rather than vice versa. The spin of the star aside from minor changes in the star's shape has no effect on the tidal forces the star exerts on a nearby planet.

Re:Relative speeds

[Anonymous Coward]

It's all relative. Think of a frisbee thrown at 155 mps rotating at 18 mps. With respect to the sun (center of the frisbee) you are traveling at 18mps. With respect to the universe (the thrower) you are traveling at 155 mps. If you are at the edge of the frisbee, the thrower will see your relative speed somewhere between 155+18 or 155-18 mps. The same can be said for hurricanes, tornados, flywheels, etc.

Re:Relative speeds

[CodeMonkey4Hire]

Personally, I would like to know how they figured out that it is a binary system remnant. Obviously, they couldn't have observed them together so is it based on computer models of what they think must have happened? This all seems just as plausible with a solitary star to me.

Re:Relative speeds

[khallow]

For a mostly intact star to be expelled with that sort of speed, something massive had to be knocked further down a gravity well, be it a binary partner, near pass of another star system, or perhaps some other blackhole in the region (there is apparently several probable blackholes with thousand or more solar masses near the central blackhole). In fact, given the amount of material that supposedly lies near the center (even though the area is relatively "starved" of mass) I wouldn't be surprised that there are several (actual not theoretical) ways for a star to get kicked out of the center.

BTW, they did trace the trajectory back to the center of the galaxy, more or less so that part is relatively solid.

Re:Relative speeds

[CodeMonkey4Hire]

Thanks. I don't doubt their trajectory calculation. They can figure that out from velocity pretty well. I don't remember seeing how long ago this would have occurred (relative to its observed location), but it had to have been so long ago that they could never find its partner. It sounds like you are telling me that they are saying binary because it is the best model they have right? That's fine with me, I just didn't like how that was passed along as fact by the article without any explanation. (I had assumed that a very close slingshot might be able to achieve a high exit velocity...)

Re:Relative speeds

[khallow]

Hmmm, it's possible that this velocity range is typical for the binary star interactions they modeled on the computer. If it is half a binary system, then there's a good chance the other star is part of a blackhole by now.

Another possibility though is that the chemistry of the star may indicate that it used to be part of a multistar system. If the star had a very close companion, then material may have been transfered between the two stars. That could show up in a spectrograph of the star.

For a star that big, untouched systems are often multistar systems with a very high probability, maybe a quarter to a half of all such stars if the impressions I got were correct.

Re:Relative speeds

[CodeMonkey4Hire]

I like the chemistry/spectroscopy idea. If that is how they decided, I could believe that. They have gotten very good at looking at H/He and metal ratios and figuring stuff out. Thanks for your insight.

SHooting Star

[SelectionShort]

Gives a whole new meaning to a Shooting Star I guess. WillY G

FYI...Speed of Light

[razmaspaz]

the speed of light = 299 792 458 m / s

or

~600 Million MPH
~1 Billion KPH

So this thing is going 1/600 the speed of light. Pretty friggin fast. What is that theory of approaching the speed of light, and is this star doing that?

Note: I did those conversions on the fly, so back off!

Re:FYI...Speed of Light

[gnuman99]

If the star travelled @ 99% c, it would still be at rest relative to itself. So, it would not be doing anything special.

Re:FYI...Speed of Light

[razmaspaz]

That doesn't make any sense. A body will ALWAYS be at rest relative to itself, right?

Re:FYI...Speed of Light

[JesseL]

not when it's accelerating. sort of.

Re:FYI...Speed of Light

[Anonymous Coward]

why?

Re:FYI...Speed of Light

[steelem]

This is where i always lost SR - we should perceive time to be passing slower on the star since it's moving relative to us. Shouldn't the star people perceive our time to be moving slower than theirs? Who's "right"? Or are both "right" and agreement only occurs if one accelerates to enter the other's reference frame. Wow this is OT... still love an explanation if anyone knows...

Re:FYI...Speed of Light

[flibuste]

No you always have a speed compared to something that is not YOU. Your speed given you as the reference point is always 0.

Re:FYI...Speed of Light

[mr_snarf]

I was going to say "they are both right", but I'm not sure if it works like you said for time. I know that for length constraction, both frames are correct, both actually do get shorter from each others POV, but not their own.
I don't gethow they can both be right since: John has a twin Fred. Fred flies off in his uber1337 ship that travels around for a while at 0.99c, while John stays on earth. Fred returns later and finds that John has aged 10 years, while fred has only aged 1 year.
This only seems to make sense if from fred's POV john's time was moving faster, and from john's view fred's time was moving slower. I'm pretty sure thats right, but in that case why can't it be the other way around?
I think I'm missing someone with this, and could probably google it, but I'm too tired and will do it tommorow, and maybe reply to Parent and myself :P

Re:FYI...Speed of Light

[mr_snarf]

Looks like I was missing something important:
http://en.wikipedia.org/wiki/Twin_paradox
So, in the case of the star, both are correct. Time is moving slower on star from our pov, and slower on earth from star's pov.

Star flung out of our galaxy?

[Matt Clare]

Please of please let it be Ashlee Simpson!

Re:Star flung out of our galaxy?

[grunherz]

Pieces ... pieces ... pieces of me ... ... leaving the galaxy!"

Hey that rhymes.

Sorry. Carry on.

To put that in perspective...

[GillBates0]

That's 0.002 times the speed of light or only about 1/500th the speed of light.

Plugging 670*10^3m/s into Lorent'z equation:

t = t'/(sqrt(1-(v^2/c2))
where v=6.7*10^5m/s
and c = 2.99*10^8,

I got a time dilation of factor of 1.00000249. That is, time in the moving system (the star) will be observed by a stationary observer to be running slower by a factor of 1.00000249.

Not as impressive as I hoped it would be when I started the calculations.

Re:To put that in perspective...

[catdevnull]

I genuflect in the general direction of your geekitude....

Re:To put that in perspective...

[Tony Hoyle]

Except the star presumably has a huge amount of gravitational force, observation the surface of the star will be affected by that.

So you're probably right about the position, but it's a debatable point about the star itself.

Re:To put that in perspective...

[KlomDark]

It still doesn't matter sir, you're going to have to pay that speeding ticket regardless of how you have baffled the court.

Re:To put that in perspective...

[nizo]

Your equation is missing a closing paren, can you explain the equation? I searched the web to no avail, and I was hoping to write a nifty perl script to compute this kind of thing.

Re:To put that in perspective...

[Alsee]

The time dilation may not be impressive, but the raw energy involved certainly is. Energy(non-relativistic)=1/2mv^2. The star is three times the mass of our sun, times v^2, times 1/2, equals 4.5*10^41 kg-m^2/s^2. That is 4.5*10^41 joules. Our entire sun produces a measly 3.9^10^26 joules per second.

It would take the entire energy output of our sun for about 36.5 million years (at a magical 100% efficiency) to accellerate that star to that speed.

-

Re:To put that in perspective...

[StarsAreAlsoFire]

http://scienceworld.wolfram.com/physics/SpecialRel ativity.html

Not a huge help. Basically the equation tells you what % of YOUR (the observer) 'time' (delta t) the person moving at velocity 'v' perceives -- e.g. the equation is used to calculate time dilation.

Same idea: E = mc^2 is incomplete. The full equation involves velocity via:

E = m*(gamma)*c^2* = m*c^2/(sqrt(1-(v/c)^2))

Re:To put that in perspective...

[Anonymous Coward]

your google calc link was boring

I would have done this :p

0.002

Re:To put that in perspective...

[StarsAreAlsoFire]

Mass Sol = 1.99E30_kg

Mass Star = 5.97E30_kg

And the relativistic mass of the star:

M' = m/(sqrt(1-(v/c)^2))
= m/(sqrt(1 - (670*10^3/c)^2))
= m/(sqrt(1 - .000005)
= m/.999998
= 5.9700149*10^30

So an extra 1.5E26kg -- about 25 Earths (Earth mass = 5.979E24 kg)

FUN!!!

Re:To put that in perspective...

[Anonymous Coward]

That's 0.002 times the speed of light or only about 1/500th the speed of light.

Yeah, only 0.002 times the speed of light is really slow... :-)

I decided to do my own calculation and figure out whether that star has more potential energy (through possible fusion) or kinetic energy (due to shooting through space unimaginably fast, and remember that kinetic energy grows with the square of velocity, so we're squaring an already-huge number here).

I figured I'd assume that deuterium + tritium = (4) He + a neutron + 14.1 MeV for my calculations. So, I assume the star is made up entirely of all deuterium + tritium. The kinetic energy of one of these pairs travelling at 6.7*10^5 m/s is about 1.87*10^-15 joules (since their mass is about 5*1.67*10^-27). If they fuse together to form helium and a neutron, that's 2.26*10^-12 joules.

So, that's 2.26*10-12 joules for fusion of those atoms, and 1.80*10^-15 kinetic energy they've got. So, I think my math is a bit imperfect, but even travelling at this huge speed, fusion can still produce about 3 orders of magnitude more energy than the star has kinetic energy.

Conclusion: damn, I knew it was a lot, but fusion can supply way more energy than I thought it could!

Re:To put that in perspective...

[Transcendent]

Question about time dilation.

If that moving star appears to going slower to us, then we're moving faster to him, correct?

But if everybody BUT that star was moving at 1/500th the speed of light, then THEY would be moving slower as observed by the star, and we could observe the star as moving faster?

That's what I don't get about relativity... the whole perspective issue with time dilation and energy, etc...

Re:To put that in perspective...

[Theolojin]

Feh. Big deal. It is moving 1,500,000 miles per hour, and that is a mere "fraction" of the speed of light. Let us have some *real* perspective here. The radius of our solar system is approximately 80AU. That is 7,436,471,008 miles. Add another astronomical unit from the sun to the earth and you get 7,529,426,895. At its current speed, if that thing enters our solar system opposite the earth, we have 209 *days* to get out of the way. Sheesh. Even if it enters our solar system on our side, it still would have to travel 80AU or 7,436,471,008 miles to hit earth. Gee. That shortens our time to duck to "only" 206 days. "Yikes."

Re:To put that in perspective...

[Anonymous Coward]

Might as well suck him off while you're down there. It's as close as he's gonna get to the real thing.

Re:To put that in perspective...

[Anonymous Coward]

So how fast are its solar neutrinos moving.

Re:To put that in perspective...

[Grand Facade]

If it's headlights are on, will it be able to see where it's going?

Re:To put that in perspective...

[AxelBoldt]

Let's assume A moves relative to B. Suppose B chooses a point p that's at rest with respect to his reference frame. He sets off an explosion at point p and 1 second later (according to his clock), another explosion at point p. Then A will measure that the two explosions happened more than 1 second apart. The exact factor is given by the Lorentz formula. (He will also think that the two explosions happened at two different locations.) Now if A chooses a point q that's at rest with respect to his reference frame and sets off an explosion at point q and 1 second later (according to his clock), another explosion at q, then B will measure that the two explosions happened more than 1 second apart (and at different locations). The situation is thus completely symmetrical and there is no problem whatsoever. If we set off an explosion at x, then A stays at x and B travels far away and eventually returns, at which point we set off another explosion at x, then both will agree that the two explosions happened at the same spot, and B will measure a shorter time between the two explosions than A. That's the twin paradox. The situation is no longer symmetrical: B was accelerated and A was not.

Re:To put that in perspective...

[Anonymous Coward]

Let's review: catdevnull's comment is scored "4" for funny. Your comment scores...mmm 0. Probably because cat's was sarcastic but creative and yours could have been written by any eighth grader on a bathroom wall. If you are going to waste the time with a post, use it as an exercise for a brain cell or two. mod parent down: troll

Re:To put that in perspective...

[Anonymous Coward]

but how many libraries of congress would that be?

Re:To put that in perspective...

[Anonymous Coward]

And for your diatribe, I give you this: eat a dick.

Re:To put that in perspective...

[Anonymous Coward]

Wow. That was so original and intelligent. Get back to class now, I'm sure it's time for fingerpainting.

Re:To put that in perspective...

[menscher]

You should learn to use Google.

Re:To put that in perspective...

[Anonymous Coward]

or better still

Re:To put that in perspective...

[p3d0]

Ok, how about this...

A typical rifle bullet travels at maybe 0.6 km/s. The fastest tank guns can fire projectiles at about 1.8 km/s. When the Space Shuttle re-enters the atmosphere, and is going so fast that it makes a huge fireball, that's 8 km/s. Escape velocity from the Earth is 11 km/s. The Earth is travelling around the Sun at 30 km/s, and the escape velocity at this distance from the Sun is 42 km/s. At this point, we're already talking about speeds that are several times greater than current chemical rockets can achieve.

My back-of-the-envelope calculations indicate that the Sun travels around the galaxy at about 300 km/s. (30,000 ly / 200 My). That's ten times faster than the Earth hurtles around the Sun. The highest speed I can get for our own Solar System is the escape velocity from the surface of the Sun. Being 215 times closer to the Sun's center than the Earth makes the escape velocity about 617 km/s. That is a very high speed, but even that is not as fast as the ejected star is moving. The difference between the Sun's escape velocity and the ejected star's velocity is about 53 km/s, which is itself much greater than any other velocity I have mentioned in this article, outside of this paragraph.

Re:To put that in perspective...

[catdevnull]

Nice, guys. Touch of class. 4th grade I think.

Hindmost

[Rorschach1]

Goddamned Puppeteers. Before you know it, they'll be fleeing with all the good stars.

Re:Hindmost

[lucabrasi999]

That is really, really funny.

Re:Hindmost

[perdu]

Goddamned Puppeteers. Before you know it, they'll be fleeing with all the good stars.

Shush! They don't want anyone to know!

Re:Hindmost

[chiph]

FYI: the 5-planet Klemperer Rosette used as a plot device by Larry Niven for the Puppeteer's home worlds has been shown to be unstable:
http://burtleburtle.net/bob/physics/kempler.html

(warning, contains java applets which will probably freeze up Firefox)

Chip H.

Re:Hindmost

[EvilTwinSkippy]

I wonder how many we don't see leaving because they didn't cheap out, and built a Dysen Sphere instead?

Re:Hindmost

[covertbadger]

Nah, I reckon Lister's just put another ball off the table and into someone's pint of beer.

Whiteholespewingtimeenginesdeadadviceplease.

Re:Hindmost

[EvilTwinSkippy]

Ok. Fine. Nit pick about that one thing, and ignore the fact he also had to invent a material called "scrith" just to hold the entire ringworld together, and that the energy required to pull the whole trick off would have been more than the output of that star for a few million years...

Re:Hindmost

[iggymanz]

that's why he added "attitude jets" to the ringworld, and I'm sure the puppeteers gave their worlds similar nudges from time to time. Anyway, if there's not five planets around this fleeing sun, we can conclude the puppeteers civilization has evolved to the point where the waste heat was so great they had to leave the sun "behind"

Re:Hindmost

[Anonymous Coward]

With all due respect to Larry Niven, this was first proposed in fiction by William Olaf Stapledon [Star Maker, 1937]. TIMELINE COSMIC FUTURE

-- Jonathan Vos Post

Ex-Adjunct Professor of Astroomy, Cypress College

Re:Hindmost

[avandesande]

I for one, welcome our new star-flinging overlords.

Re:Hindmost

[AJWM]

The Puppeteers had (have, will have, whatever) both antigrav and artificial gravity. I think they could deal with any instability.

Re:Hindmost

[danila]

Great link, thanks a lot!

Any astronomers out there?

[Marshy101]

"Only the powerful gravity of a very massive black hole could propel a star with enough force to exit our galaxy," explained Brown.

As far as I understand it black holes are created when stars collapse and gravitation force depends on the amount of matter present. So why would a black hole produce a greater gravitational force at a distance than any massive star? And why would a great force at the centre of the galaxy be inclined to spit out stars at huge velocities? I assume the companion star is relevant.

Re:Any astronomers out there?

[FirienFirien]

The ergosphere around a black hole is full of matter that's orbiting the black hole at a speed that's not enough to get back out again - as a fast body comes through, it slingshots through the buzz of energy provided and comes out faster than it went in. This is above the point of no return, but there's still a lot of energy flying around there.

Re:Any astronomers out there?

[Anonymous Coward]

There's a limit to how massive a star can be -- we don't see any stars more massive than about 150 times the mass of the sun, probably because they can't form that massive. Black Holes, on the other hand, are not limited in mass (they can swallow other things to increase their mass). The one at the centre of the Galaxy is several million times the mass of the sun.

Re:Any astronomers out there?

[Marshy101]

The ergosphere around a black hole is full of matter that's orbiting the black hole

Does this mean that the mass of the blackhole is increasing as it picks up stray matter?

Re:Any astronomers out there?

[DarkHand]

They're just basically saying that the star was slingshotted(new word?) out of the galaxy by way of the black hole at the center of the galaxy. The same way that we use planets to slingshot probes and increase their velocity to get them to their destinations faster. Just at a much larger scale.

Re:Any astronomers out there?

[Anonymous Coward]

If you are running linux, and have xscreensaver, look at the "grav" screen saver.

Basically an object that is attracted to a larger object can either fall directly into the larger object, obtain a stable orbit (assuming no other outside influences), or approach the larger object at a critical enough angle, whip around it (gaining quite abit of speed) then break away (slingshot effect).

NASA has used this for some of the deep solar system probes, swinging the probe around Jupiter. The probe picks up some energy, while Jupiter loses the same amount.

Re:Any astronomers out there?

[Anonymous Coward]

Think about the galaxy as a large bowl, that isn't very deep.

If you visualize it as a soup bowl (a model of the galaxy without a blackhole, and instead a large protostar cloud in the center), when it spins, nothing gets ejected because the further you go away from the center, the slower the rotation is.

If you correctly visualize the galaxy as toilet bowl, with a blackhole in the center, the outside would rotate faster than the inside, and matter will get ejected.

Because of the blackhole, as matter approaches the event horizon it stops (relatively), but in a non-blackhole model, as matter approaches the center of the galaxy, it would speed up, causing the eventual collapse of the galaxy. In fact, if you follow my model, the galaxy might not have always had a blackhole, and one could have been created once enough matter accumulated in the center.

But, I am not an astronomer, I am a sociologist. So ask me about social heirarchies.

Re:Any astronomers out there?

[FirienFirien]

Yes, this is why black holes get so massive. They suck stuff in, and they feed on the extra mass. Must. Refrain. From. Fat. People. Joke.

Re:Any astronomers out there?

[dhakbar]

Do you think there will be a class war in America?

(asking the sociologist)

Re:Any astronomers out there?

[Anonymous Coward]

wouldn't it be slungshot?

Re:Any astronomers out there?

[The_countess]

the black hole presumed to be at the center of our galaxy has probably swallowed a huge amount of stars by now, so its gravity pull will be MUCH larger then even the largest know starts. as for the slingshot effect. as something small(er) gets pulled toward something heavy its increasing speed all the time. by the time the small object has reached the heavyer object and is about to do a orbit like turn its speed has become so great that it shots away from the heavy object at great speed because of the centrifugal force. they use the same techniek to give space probes some extra speed inside our solar system, aspecialy if they are going for the planets on the outside of our system.

Re:Any astronomers out there?

[Somegeek]

All of the real astronomers are busy right now. Press 1 to be connected to a geek instead or 2 to leave a message.
-1-
Thank you.
The answer is : Black holes can be compilations of many stars. The one at the center of our galaxy that they are talking about is currently believed to be 3.7 million times the mass of our Sun (give or take 1.5 million).
This is just like we slingshot space probes past planets to get a gravitational speed boost, this star got pulled in towards the black hole but barely missed and got a the mother of all gravitational slingshots. I would guess that the fact that it had a companion was unimportant, and could have happened if it had been it had been a single star on the right trajectory.

IANAA.

Re:Any astronomers out there?

[adlj]

'cause black holes don't have a size limit. a really big star last very little, then it becomes supernova and finally a black hole... the black hole does nothing but gobble more matter and grow, grow... if the star comes along the black hole with the right trajectory, it can have a slingshot effect same as the one we used to accelerate the Voyagers, but on a much larger scale... by the way, with black holes this should work even better as you can get as close at them as you want as long as you manage to stay out of the event horizon. big star, instead tends to be much less dense than Black holes... so you can't get so close...

Re:Any astronomers out there?

[another_henry]

So why would a black hole produce a greater gravitational force at a distance than any massive star?

It doesn't, but the black hole is very massive - considerably more massive than any star in the galaxy.

And why would a great force at the centre of the galaxy be inclined to spit out stars at huge velocities?

It's tricky to explain and not terribly easy to get your head around, but I think the principle is similar to this demonstration (check out the video). The grav. potential energy of the companion star due to its attraction to the black hole is transferred into kinetic energy in the ejected star.

IANAPyet so please correct me if I'm wrong.

Re:Any astronomers out there?

[log0n]

...that the star was slingshot out of the...

Take off the 'sling' modifier: ...that the star was shot out of the...
or ...that the star was shotted out of the...

That's the rule; works in pretty much any instance you'll come across. If it doesn't, there's generally another word to fix it (ie: runned != ran, stoled != stole/stolen, etc). Hope that helps!

Re:Any astronomers out there?

[another_henry]

I thought the grandparent was asking whether a black hold would have the same field strength as a star of the same mass. Also, aren't there a number of supermassive stars (up to 50 solar masses) that weigh more than conventional black-holes resulting from supernovae (~20 solar masses)?

I agree that in general most black holes are more massive than most stars.

Re:Any astronomers out there?

[SirBruce]

I think the correct verb is "slingshat".

Bruce

Re:Any astronomers out there?

[Tired and Emotional]

You don't get a slingshot effect from the black hole at the centre of the galaxy in the same way as you do from a planet because the black hole is at rest. The presence of a companion was crucial.

Its more like a satelite performing a rocket burn near the sun in order to gain velocity. Because the exhaust comes out moving more slowly (relative the the far away observer) than it would if the satellite was in higher orbit, the satelite gets much more boost.

In the case of a binary system and the black hole, I expcect what happens is the tidal forces break appart the binary system. The component that was travelling in the direction of motion (relative to the black hole) gets ejected with increased velocity while the unfortunate companion gets swallowed up - or goes into a much tighter orbit.

I wonder how much boost you get from the black hole at the centre of our galaxy as a result of frame dragging? Does frame dragging in fact produce a boost? (I would expect so) Do we have any estimates of the effect for the galactic centre?

Re:Any astronomers out there?

[Anonymous Coward]

Somehow that sounds like a masturbation technique.

Re:Any astronomers out there?

[Thuktun]

the black hole presumed to be at the center of our galaxy has probably swallowed a huge amount of stars by now, so its gravity pull will be MUCH larger then even the largest know starts.

The mass was already there in the combination of the earlier black hole and the stars it hadn't yet "swallowed". Mass and energy are conserved.

it shots away from the heavy object at great speed because of the centrifugal force.

No, there is no such force. What people refer to as centrifugal force is the effect felt when inertia resists an inward centripetal force, in this case due to gravitation. You can't possibly gain speed due to inertia, you already have it.

they use the same techniek to give space probes some extra speed inside our solar system

Not exactly. An object on a parabolic or hyperbolic trajectory around a planet gains speed as it approaches the planet, but loses speed as it recedes. A slingshot trajectory allows you to get somewhere faster with less fuel not because it speeds you up, but because it allows you alter your trajectory without using fuel.

Re:Any astronomers out there?

[Physics Dude]

The same way that we use planets to slingshot probes and increase their velocity

Sorry, but it doesn't quite work that way in this case. In a slingshot trajectory, if you measure from the inertial reference frame of the massive body (the galactic core in this case) you will observe the incoming and outgoing velocities of the less masive object (the star) to be roughly equivalent. In the reference frame of the less massive object however, this may result in a huge velocity gain or loss depending on the interaction. If the massive object providing the slingshot effect is at rest with respect to our galaxy (as in this claim) then the less massive star cannot appreciatively change its velocity with respect to the galaxy without gravitational interaction with other objects which are not at rest with respect to the galaxy.

Little relativistic phenomena

[grahamsz]

They are only moving a 0.002c. I can't be bothered doing the calculations but it's probably not significant.

Re:Little relativistic phenomena

[Fulcrum of Evil]

Wrong. .22c (1/5th the speed of light). You were off by a factor of 100 - you forgot to handle the percentage...

Nope, I got .0022c. There's no percentage involved - c is a unit velocity.

Re:Little relativistic phenomena

[timster]

From google:
c in feet per second: 983,571,086

1,500,000 miles per hour in feet per second: 2,200,000

I'm not "working with percent", and obviously the second number is nowhere near one fifth of the first. Dividing the first by the second leave me with 0.0022. So 0.002c is correct.

If I wanted to express that as a percentage I would multiply by 100 for 0.22%, or two tenths of one percent.

Re:Little relativistic phenomena

[EulerX07]

The speed of light (c) is 300 000 km/s. 670/300000 = 0.0022. It's going at 0.0022c.

Don't worry, you're the not the first person to post disinformation on this site and get modded up as informative. Also, you should have worked with the metric values instead of messing around with the imperial values. Ye olde english system is great for measuring stuff in your trousers, but not as great for astrophysics.

Re:Little relativistic phenomena

[wwest4]

Try rounding and using simple arithmetic on the powers of 10 in order to check your answer.

round 1,500,000 to 2E6
round 3,600 s/h to 4E3
-> 2E6 * 4E3 = 8E9

round c 186,000 mi/s to 2E5
-> 2E5 / 8E9 = 0.25E-4

percentage conversion *100 is *E2
-> 0.25E-4 * E2 = 0.25E-2 = 0.0025%

Relativistic effects are negligible.

Re:Little relativistic phenomena

[attam]

On Google - enter "1,500,000 miles per hour in feet per second", then seach for "speed of light in feet per second."

or "speed of light in miles per hour"... but i guess that was just too obvious.

Re:Little relativistic phenomena

[the_mad_poster]

c in mph

is sufficient. Google recognizes some constants as well as common unit abbreviations such as "km/s", "mph", etc.

Re:Little relativistic phenomena

[OOGG_THE_CAVEMAN]

1.5 million miles per hour is only 671,000 meters/second, or 0.00224 the speed of light. Relativistic effects are basically negligible.

Re:Little relativistic phenomena

[Anonymous Coward]

Come on mods, that was really funny.

Re:Little relativistic phenomena

[Rick.C]

Ye olde english system is great for measuring stuff in your trousers, but not as great for astrophysics.

A word of caution there, mate. How do you know 'e 'asn't got some astrophysics going on in 'is trousers?

Re:Little relativistic phenomena

[Puff Daddy]

If you're working in percent, that's fine, but no one else is. If we decided to start working with percent we would find that the star is moving at 0.22% of c. I just gave you the answer, now its your job to find the expression. Also, never, ever use the imperial system in science. Pretend the speed of light was never determined in feet per second.

Re:Little relativistic phenomena

[techno-vampire]

Also, never, ever use the imperial system in science.

You have to, here, because the velocity was given in that system. What I did was multiply by 5280 to change to feet, 12, giving me inches, then divide by 2.54 to get centimeters. Not exactly hard, but you do have to remember all the steps. Knowing the conversion factors helps, but I'd hope most people here do. (My sister still has to ask when needed, but that's because it didn't interest her in school. But then, she's not a /.er, either.)

Re:Little relativistic phenomena

[PateraSilk]

Trouser measurements, eh?

Wow! It's 0.061 rods long!

Re:Little relativistic phenomena

[EugeneK]

Actually I find the metric system is better for stuff in my trousers too - micrometers, picometers, etc.

Re:Little relativistic phenomena

[EulerX07]

Then why did your girlfriend keep calling you Mr. Point o' two at the last office party?

Re:Little relativistic phenomena

[Anonymous Coward]

That's nothing. I did the Kessel run in 12 parsecs!

Slashdot...

[greypilgrim]

Yesterday's news...Today!

Cast away a falling Star...

[stkpogo]

Bruce Willis and Tom Hanks in a Great Solar roundup,
yippie-ki-yay.

Lever

[suso]

I guess someone finally found a really long plank and a place to stand.

Re:Lever

[sconeu]

Moderated +1 Archimedes Ref.

Re:Lever

[CCRancor]

I guess obesity really is the biggest problem in the universe nowadays...

Still...

[SharpFang]

...only 0.2% c

Re:Still...

[aeroelastic]

Yeah, but that's still one hell of a Doppler shift!!

This proves it

[That's Unpossible!]

The speed of light is 1.5 million miles an hour!

a better question

[kmcg83]

So some force made it start travelling this fast. This must have been a very strong force, and it's implied that the reason is that it was flung out by the gravity of the black hole. I'm wondering why the star was capable of staying together. I mean, It must have come pretty close to the center of the galaxy, and probably would have been destroyed by tidal forces, then 'eaten' by the super-massive BH. I can't exactly do the math to back that up though

Re:a better question

[Anonymous Coward]

Actually, supermassive black holes like the one at the center of our galaxy do not exert tidal forces like smaller black holes...although the total gravity is very intense, the gradient is actually quite gentle.

Re:a better question

[fiddley]

I don't think that massive acceleration, such as that the star may have experienced, would have the damaging effects on it as though it were an object on Earth.

For example, if you spin a candy floss around your head here on earth, centrifugal force (Yes, I know there really no such thing!) would eventually pull the main candyfloss body off of it's stick in one big lump. However it is actually the friction of the air around you which rips the candy floss apart. In space there's no such friction, only gravity and momentum - these would combine in roughly the same way the centrifugal force would, pulling the star towards it in one big lump. I would assume that any part of the star would have fairly uniform forces acting on each point of it. Therefore, the star would have changed direction and begun to accelerate away with very little disruption (relatively speaking, of course, it may not have been so gentle if you were aboard any planets that happened to be orbitting it!)

that said, I completely made that up, and the truth could be far different...Who can tell for sure?

Inertia & Momentum

[mreed911]

While this seems astounding, leaving some to wonder "how's a star stay together at 1.5MM mph?", it's important to remember that, for all intents and purposes, it's travelling through NOTHING, through a vacuum. As long as its velocity is stable (not running into things to slow it down), there's no inertia to change it's shape, etc.

Is there *really* a difference, physically, on an object moving at 1.5MM mph and one standing completely still, if they're not interacting with anything else? No. Their inertias are the same, so their physical properties and interactions are the same.

Momentum, however, could be a bitch. Imagine this star slamming into another star (or, a la the Death Star, a small planet in the Aldeberan system). Ka-pow, with the graphic like on the old Batman series! Would make Levy-Shoemaker look like a BB gun (you're gonna put your eye out!)...

Re:Inertia & Momentum

[MikeDX]

Imagine this star slamming into another star

What, you mean like in 76 years when it comes back, like halleys commet?

Re:Inertia & Momentum

[Anonymous Coward]

While this seems astounding, leaving some to wonder "how's a star stay together at 1.5MM mph?"

That's not what people are asking. They're wondering how it stayed together through the enormous tidal forces at the center of the galaxy.

Re:Inertia & Momentum

[Anonymous Coward]

I'm wondering what the hell "15MM mph" is supposed to mean. 15 millimeters mph? Mega Moron? Mega Million?

Re:Inertia & Momentum

[forand]

You are missing the point. It is leaving the galaxy. Everything else we have seen in our Galaxy is gravitationally bound to it thus it cannot leave, this is amazing because it moving above the escape velocity of the galaxy.

Re:Inertia & Momentum

[MindStalker]

Nope all stars are moving, infact there are some galaxies out there that are moving away from us at close to the speed of light (theoretically some are moving faster, but obviously we can't see them). That is the entire intent of einstein's theories is that in space with no referense point you can't tell how fast your moving, only how fast you are moving in referense to other things. I'm guessing this star is moving faster than the other stars, or orbiting something, which is the only movement you can really detect without a reference (rotation).

Re:Inertia & Momentum

[Anonymous Coward]

Aldeberan system

Take away his Geek Card (TM)

Re:Inertia & Momentum

[jafac]

I remember playing with "gravity simulator" software on various computers. When you sent two obects into a near-miss, the close proximity would sling-shot them at tremendous speed.

I always wondered if there were stars, further-in our galaxy, that had had such close-encounters, and were now flinging in our direction at tremendous speed. Given the doppler effect, the star's radiation might even be shifted well out of the visible spectrum, and we might not even be aware of it's approach (without UV/Xray astronomy).

It wouldn't take a hit, or even a near-miss, to end all life on this planet. A distant miss, enough to perturb our orbit, or the path of the sun (and thereby perturb the orbits of ALL objects around the sun) - could be catastrophic.

Just seems though, we've gone this many billions of years without such an encounter - maybe they're rare. I mean - we don't see thousands such stars speeding around in other directions, so I guess there's no reason to think there may be one pointed at us. . .

Re:Inertia & Momentum

[Anonymous Coward]

Actually, inertia is a measure of mass, so it actually does have quite a bit of inertia (3 solar masses worth). On the other hand, as you point out, there is not a great deal of stuff in its way, so the ram pressure against it is tiny (different from when planes move through the air, or Martian probes do aerobraking).

Stars rarely collide --- galaxies just aren't sufficiently densely packed with stars for them to have a decent probability of colliding.

Re:Inertia & Momentum

[kill -9 $$]

I dunno, something about this article got me thinking about all the near misses we supposedly have with asteroids and what not. I mean, how cool would it be to have a gigantic friggin star hurled at the solar system taking out planets galore and what not.

Granted we'd all be dead, but what a way to go...

Re:Inertia & Momentum

[fiftyfly]

Is there *really* a difference, physically, on an object moving at 1.5MM mph and one standing completely still, if they're not interacting with anything else? No. Their inertias are the same, so their physical properties and interactions are the same.

Except that is was part of the galaxy and now it's moving away at some .2% of C. This would sugest some rather significant acceleration at some point, no?

Re:Inertia & Momentum

[arootbeer]

This is true. However, because the star is relatively dense and the entire thing is being influenced by a gravitational field that is relatively constant across the breadth of the star, the entire star would be accelerated at the same time. Also, for lack of a better cosmic term, there is very little friction to cause bits of the star to be left behind when it accelerates.

When a baseball is accelerated through the air, friction probably causes some microscopic bits of the leather to stay behind. But because of the relative density of the object to the medium, the majority continues to move forward as a whole. The parent was not necessarily implying that the star is not losing any mass, just that the loss is likely insignificant compared to the total mass because of the almost complete lack of anything that would cause the star to lose pieces of itself. (Within the medium of space itself...obviously this excludes planets, asteroids, other stars, etc.)

Re:Inertia & Momentum

[gfody]

just don't piss off omicron pursei 8

Re:Inertia & Momentum

[fiftyfly]

I could be a little off in the math but I'm thinking of a couple of things, namely tides and spin. My back of the envelope thoughts include:

• 89/mph fast ball == 40m/s
• d=3m (armspan and abit), a = 533m/s^2 and t = 0.075s
• that baseball would need to accelerate for more than 20minutes to reach 670000m/s

Our sun is relatively stationary with respect to the plane of the galaxy but it's already spinning and, I gather, not all at the same time. it's not a solid body and the poles don't keep time with the equator. It cleary doesn't behave like a solid body, unlike the baseball. So to move such an object without inducing tides or significantly deformation the gravitational field, one would think, must be enormous and acting at quite some distance. So why is there just one star and not a whole bloody spiral arm zooming across the cosmos?
Even if my grav field assumptions are wrong what are the chances that you could accelerate any object, solid or not, that's already spinning without changing that spin?
I can't help but think that either my assumptions are wrong or there's something really really strange about a big blob of gas accelerating to a non trival fraction of light speed over a short enough duration that it's done so and still remained in the neighboorhood.

Re:Inertia & Momentum

[pclminion]

I remember playing with "gravity simulator" software on various computers. When you sent two obects into a near-miss, the close proximity would sling-shot them at tremendous speed.

That doesn't happen in reality. In reality, if two objects have a net negative energy (i.e., potential energy is larger than kinetic energy) then they are in a "bound" state and will stay bound until some external force adds the necessary energy.

The reason you can pull this off in gravitational "simulations" is because they use inaccurate techniques to integrate the equations of gravity and motion. In the real universe, you need at least three bodies to get a slingshot effect. (I put simulation in quotes because it's not a very realistic simulation of gravity, as this physically impossible artifact demonstrates.)

Re:Inertia & Momentum

[arootbeer]

IANAAP (I am not an astrophysicist)

With that said...what does the spin of the star (or, more importantly to your question, the resulting spin) have to do with its linear motion, which happens to have been changed by an outside force? I'm not bashing you, I just don't see how it's relevant.

We're (supposedly) talking about a super-massive black hole, which would be expected to have an enormous gravitational field which would be able to act at a great distance. (In fact, it's got quite a few spiral arms zooming around the cosmos, although they're trapped in orbit around it. :)

Re:Inertia & Momentum

[fiftyfly]

IANAAP (I am not an astrophysicist)

Neither am I, by any stretch of the imagination

With that said...what does the spin of the star (or, more importantly to your question, the resulting spin) have to do with its linear motion, which happens to have been changed by an outside force? I'm not bashing you, I just don't see how it's relevant.

Not that one effects the other that much but spin can be very destructive. That being said gyroscopes are funny about acceleration.

We're (supposedly) talking about a super-massive black hole, which would be expected to have an enormous gravitational field which would be able to act at a great distance. (In fact, it's got quite a few spiral arms zooming around the cosmos, although they're trapped in orbit around it. :)

I'm thinking that a single star, gauged against the size I think we'd have to be talking about to avoid destructive tides, is pretty small.

That's not a star

[Anonymous Coward]

That's not a star. It's just the aliens leaving after they saw the state the earth was in.

Alien1: zork, zweek ook oort leev froogh?
(Eeww, what's that smell?)
Alien2: sfreet wosk sder sprinna sprinna
(We seem to be approaching some wierd blue planet)
Alien1: Whoroska frisht squuort
(I wonder what's happening down there)
Alien2: Splurk.
(No clue, but I'm not waiting around to find out.)

This must mean

[flumps]

"Only the powerful gravity of a very massive black hole could propel a star with enough force to exit our galaxy," explained Brown.

This must mean that the galaxy is actually speeding up?

Or does it just mean the stars mass is greater than it was before..?

If its neither of these, why has the star suddenly broken away from the galaxy. If its a massive black hole, surely the gravitational pull would have kept the star in rotation around, not chucked it out..

Re:This must mean

[RichMan]

Sling shot:

1) have lots of mass and dive into a gravity well. The gravity field and the mass cause you to accelerate into the well.
2) drop mass at the bottom of the gravity well
3) remaining mass has extra speed from the dive but will feel less pull back into the well on the way out
4) result is increased speed away from the gravity well, cost was loss of mass into the well

It is quite easy to see how this could happen to a star getting sucked into the well around a black hole.

Re:This must mean

[thpr]

This must mean that the galaxy is actually speeding up?

No

Or does it just mean the stars mass is greater than it was before..?

Yes, but only very slightly... since it's traveling at about 1/500th the speed of light, it did gain some mass, but very, very little relative to its original mass

If its neither of these, why has the star suddenly broken away from the galaxy

It all has to do with the angle and distance at which the star approached the black hole.

If it passes by a long distance away or at a slow speed (I don't know the equation to show you the threshold of speed/distance/mass), the chance is that it will enter some form of orbit, if irregular.

If it is nearly tangent to the object (but doesn't strike it), and it is already moving at a high enough velocity, then it will use the black hole as a slingshot and will gain velocity. You can check out the Cassini satellite's mission trajectory to see how it used Venus and Earth to gain velocity (relative to the sun)

Re:This must mean

[thpr]

2) drop mass at the bottom of the gravity well

Not required.
- Assume you are at the point 1,-10 and moving at 1 unit of distance per unit of time toward 1,+infinity (directly 'up' in cartesian coordinates)
- Assume a large point mass is located at 0,0

Skipping a lot of mathematics to show how much the object is accelerated, you can observe that when the moving object passes from 1,-10 toward 1,0; it will be slightly pulled toward the mass (to perhaps 0.99,0). As it continues along, the net force by the object at 0,0 pulls the moving object roughly toward -infinity,0.

However, since this is space, and a vacuum, there is nothing to slow the velocity the object already has (yet the large mass IS accelerating the moving object).

Therefore, the object now has a velocity equal to 1 unit of distance toward 0,+infinity PLUS some (smaller) velocity toward -infinity,0. NO change in either mass is required.

Re:This must mean

[McNihil]

Gives meaning to have Jupiter and Saturnus (and other smaller giants) in our solar system as a buffer doesn't it. Mars will need to be hospitable by then just in case so we don't get sucked in. Talking about a coupld of billion years from now but hey... one has to start early.

Re:This must mean

[flumps]

Ah thanks good explanation... Thats why I flunked Physics. ;)

Re:This must mean

[Ohreally_factor]

Thats why I flunked Physics.

Hey, at least you didn't ask about the star traveling backwards in time.

Re:This must mean

[jonatha]

By conservation of energy, shouldn't the moving object have to shed the amount of energy it aqcuired while falling towards 0,0 in its escape from the mass at 0,0, leaving it with the same velocity "afterwards" as it had "previously"?

I never could get this straight...

Re:This must mean

[thpr]

In order to avoid calculation (I'm trying hard to avoid doing the math), this is answered best by looking at a few corner cases.

First, let's assume the mass at 0,0 can be passed through without slowing us down. In that case, if we start at 0,-10 rather than 1,-10, we have no lateral (delta x) movement at all, the velocity at 0,-10 is equal to the velocity at 0,10 (becuase the moving object would accelerate from 0,-10 to 0,0 and decelerate from 0,0 to 0,10 by the exact same amount). This is exactly the case that you are referring to in your post.

Second, let's look at an object that is stationary at 4,0. Gravity would pull that object toward 0,0, even if both objects were initially motionless. Remember, position = x0 + v0 * t + (a * t^2) / 2 ... This is a situation where we are converting potential energy (distance from a large mass - meaning using gravity) to kinetic energy (motion). This change from potential to kinetic is how we avoid violating conservation of energy. The moving mass also (slightly) pulls the larger mass at 0,0 closer, so they might strike at 0.01,0 ... this is how conservation of momentum is maintained (because momentum is mass * velocity and velocity is a directional vector, while speed is an absolute value of the length of the vector... thus, with the vectors in perfectly opposite directions, the net momentum is always 0 [with both at rest at the beginning of the exercise]).

So provided that the velocity is high enough that the velocity in Y is >> than the acquired velocity in X from the second case, we are OK. In fact, the velocity in Y at the closest point of approach should be at least the escape velocity of the mass. In that case, the velocity is high enough that the entry angle and the exit angle of the moving object should vary by less than PI/2 radians (you will note this is true in the case of the path of Cassini linked to from my other post). In this case, the direction of the object was changed, but it still has enough velocity to escape the gravity from the mass at 0,0. The net velocity is also faster than when it went past the large object, because it converted potential energy into kinetic energy.

However, if the velocity in Y is too slow, then one of two things will happen. If velocity is too low, the object will do some small arc around the mass until it actually strikes it (this now assumes the mass has some volume). If the velocity is slightly faster, such that it is not low enough to strike the object, but not fast enough to escape from the object, then the moving object has functionally undergone what would be called orbital insertion. The velocity threshold here (between striking and not striking the mass) is called the orbital velocity. Thus, the moving object would permanently be a satellite of the mass at 0,0 (though the orbit may be irregular for some time). For some more on thse velocity thresholds, visit How satellites work

Re:This must mean

[pclminion]

If it is nearly tangent to the object (but doesn't strike it), and it is already moving at a high enough velocity, then it will use the black hole as a slingshot and will gain velocity.

That's not right. If the only things in the universe were the black hole and the star, the star could never "slingshot" away from the black hole no matter how it approached it (unless it was already traveling faster than the hole's escape velocity, but let's assume it isn't).

The slingshot effect requires three objects. It isn't accurate to say that the black hole ejected the star from the galaxy. What is accurate is to say that there was an interaction between three bodies (probably two stars and the black hole) which resulted in one of those stars being ejected from the galaxy.

Re:This must mean

[flumps]

Time travel is impossible. Everyone knows time is a vector quantity and measures rates of change don't they?

don't they?!

Re:This must mean

[Ohreally_factor]

Using gravitational effects of large masses to go backwards or forwards in time is an old staple of Star Trek, so I'd be willing to bet you $0.25 that there are a few slashdotters that believe it's possible.

that's what you get...

[jpellino]

... for being the last one on the galactic ice-skating chain of kids^H^H^H^H stars.

Supermassive black holes

[Spy der Mann]

Recently I saw on Discovery that many galaxies (if not all) were orbiting around supermassive black holes. And that the orbiting speed of the stars is proportional to the black holes' mass. This is known as the "M-sigma" relation.

This meant that the supermassive black holes actually contributed to the process of galaxy formation.

The theory is more or less the following:

In the center of a galaxy-sized gas cloud, a star collapsed, forming a black hole. The black hole began eating the gas around it, forming a quasar (quasars are the matter just about to be swallowed by a black hole, disintegrating and generating enormous amounts of energy).

The quasar, due to its high temperature and rotational speed, heated the surrounding gas cloud, activating a chain reaction that gave birth to all the stars in the new-forming galaxy.

Eventually, the quasar pushed away the stars, so the black hole could only be fed by the quasar itself. After that, the black hole enters a dormant phase (it has nothing else to eat), and the galaxy is already formed (of course, I'm talking about a process that takes billions of years).

Re:Supermassive black holes

[bigmaddog]

Call me a bitch about details, but... (I know, someone else will be a detail bitch about my details.)

Quasars radiate tremendous amounts of energy not because matter "disintergrates" as it falls inwards but merely because it falls inwards.

It's as if a bucket of bricks fell on your head from ten stories up (well, almost) - while up there, the bricks & bucket have potential gravitational energy. As the whole thing falls, gravitational potential energy is converted to kinetic energy, some of which is lost to friction with the surrounding air. It may generate sound, like a low whistle or thunderous roar, depending on the aerodynamic properties of the bucket. When the bucket hits, all the remaining kinetic energy is dissipated by your skull and brain, and "radiates away" as sounds and splattering gore. (This last part about the brain and plattering is not necessary for the analogy but I just like talking about gore.)

So, same thing with quasars, more or less. Stuff far away from the quasar has a lot of gravitational potential energy because quasars are so damn massive, which leads to powerful gravity. As it falls inwards, it trades this energy for kinetic enrgy, moving faster, and, as it grinds against other stuff in the accretion disk around the quasar, some of which is moving slower, some of this energy is lost to friction, except instead of sound (whistling) with the bucket & bricks, you get EM radiation. (If the bucket fell from really high up, it might heat up from friction and start emmiting some radiation of its own, in infra red and then in visible light.)

Sice the black holes at the centre of galaxies are so damn huge, and because falling into a black hole release several orders of magnitude more of the massenergy of a piece of matter than fission or fusion ever could (astronomy textbook not at hand, so can't quote the numbers), we get a whole lot of radiation this way, and so quasars are really really bright.

Re:Supermassive black holes

[wayne606]

I'm guessing that a large part of the radiation from black holes is like synchrotron radiation - charged particles being accelerated in a magnetic field (i.e. temporarily in orbit) will give off radiation. This radiation (and plain old friction) is probably a big reason that the particles don't stay in orbit forever but spiral in eventually.

Stuff almost never falls directly into a black hole... Because of conservation of angular momentum it will generally go into orbit.

Re:Supermassive black holes

[doombob]

What if we're already past the event horizon of a supermassive black hole in the center of our galaxy? How much time do you predict we have left?

Re:Supermassive black holes

[mbrother]

Some of the energy is in the form of synchrotron, but this is more important in so-called radio-loud objects with jets, and is beamed along the jets. The vast majority of the radiation is thermal, either from the hot accretion disk or reprocessed radiotion from surround dust heated to a few hundred degrees kelvin. Quasars are my specialty.

Re:Supermassive black holes

[raduf]

Call me a bitch about details, but... (I know, someone else will be a detail bitch about my details.)

Well, at least it's not a surprise ;)

Around bigger black holes, the matter doesn't just fall into but creates a vortex, a high-velocity disc around the black hole. Bigger the black hole, faster the disk and (like with our "outcast" star) some of the matter just spins too fast and escapes. Now the interesting bit is that with really big black holes like quasars the amount of energy around the black hole, kinetic or otherwise, is so great about half the matter escapes. Which let scientist to beleve for a while that quasars are actually white holes.

the other way around

[Anonymous Coward]

Scientists from the other side of the galaxy have found evidence of a small planetary system, made of one star of about 1/3 of normal size and its 9 planets moving falling into a black hole at incredible speed.

Does anyone know...

[midifarm]

if this thing is accelerating, decelerating or at a constant speed?

Peace

Re:Does anyone know...

[Tony Hoyle]

It could easily be doing both the first and third... the second really isn't a meaningful description of anything.

OTOH to be accelerating it'd require an input of force even if it was only changing direction. At that speed I doubt the gravitational force of the stars on the edge of the galaxy is enough to do much to it.

Re:Does anyone know...

[Overzeetop]

Well, if we can simplify the motion to (1) the galactic core and (2) the star, Kepler's equations require that it be decelerating. Based on the fact that it has 2x the escape velocity of the galaxy, that would put it on a hyperbolic path with the galactic core at its focus (the real one). After an (infinite) period of time, it will slow to a spped which is 1.7x escape velocity (v-inf^2=v^2 - v-esc^2) based on the 2x number being the maximum velocity obtained. This is more commonly known as the "hyperbolic excess speed".

This post brought to you in part by Bates, Mueller, and White...the best textbook value in the world ($6 for an astrodynamics text...and a pretty good on at that).

Re:Does anyone know...

[EvilTwinSkippy]

Theoretically, decellerating.

Observationally, we don't know. It required a lot of observations to gauge its proper speed. It is going to require a lot more to gauge how much that speed is changing.

One moment of insight I had into how much we don't know about our universe was fooling around with some software from NASA. (Perks of working in a science museum with a planetarium.) One of the items you could toggle on you flights around the solar system and surrounds and ... well just about anywhere in the observable universe... was paralax error.

That's a neat orange strip that shows all of the possible values that the paralax, the difference between the angles observed at different places. It's used to calculate distance. Even on nearby stars, we have paralax errors that place them over ranges of hundreds of light years.

We can measure the relative direction of a star easily. Determining the distance is largely voodoo. Especially when you throw in "proper motion." What we see as the constellations are changing slowly above our heads as the stars themselved move relative to one another and Sol.

Re:Does anyone know...

[CrankyFool]

Probably.

Re:Does anyone know...

[Anonymous Coward]

This post brought to you in part by Bates, Mueller, and White...the best textbook value in the world ($6 for an astrodynamics text...and a pretty good on at that).

You forgot to whore a link to Amazon, you insensitive clod! :D

WOW

[PacketScan]

This is a awesome finding.. What i would like to know is still a mystery.
Are we circling a black hole?

Re:WOW

[Anonymous Coward]

The short answer:

Yes.

Where are

[maroberts]

Starcops when you really need them?

Officer! Stop that star for speeding!

Hey dude. Your math smells

[DupyMcCopy]

1.5 million mph is about equal to 1/400 of the speed of light. The reasoning is because the speed of the star is 1.5 million mph over the speed of light 600 million mph. So you get 1.4m/600m which reduces to 1/400.

/. a star?

[Me-The-Person]

Can a star be /.'d? If so, did we just change the orbit of 5 other planets?

Confirmation

[way2slo]

/usr/dt/bin/xlock -mode galaxy

There's your confirmation. At least on some Solaris servers I've seen.

The end is near!!

[Ogrez]

At last.. Jesus is taking his ball.. AND GOING HOME!!

repent!

Re:The end is near!!

[EvilTwinSkippy]

Oh hell, I have a few more million years. Throw another steak on the flames and bring me a virgin.

Or is that bring me a steak and throw another virgin on the flames?

Re:The end is near!!

[Anonymous Coward]

> Oh hell, I have a few more million years. Throw another steak on the flames and bring me a virgin.
>
>Or is that bring me a steak and throw another virgin on the flames?

Neither.

It's "Throw another virgin on the flames. Bring me a steak."

Heads Up!

[IBeatUpNerds]

Duck!!!

Impressive?

[SharpFang]

20s across Earth
2 days for the distance between Sun and Earth
1800 years to move between Solar System and Proxima Centauri
43 million years to cross the Galaxy.

Man...

[Mindwarp]

...just thinking about the kinetic energy that thing must be carrying with it makes my head spin.

All we need now is a super-massive baseball mitt on the end of a hyper-massive wooden pole hooked up to a mega-massive generator spindle.

Re:Man...

[Mindwarp]

Mass of the star: approx 6x10^30 kg Velocity: 670,000 m/s Kinetic energy = 0.5 x m x v^2 Energy is very approximately 1.3x10^42 Joules, which I believe is enough to heat a Googleplex of Libraries of Congress for 3.141 Millenia.

Re:Man...

[melandy]

Or if you prefer, that's 81,944.6962 fortnights according to the Google Calculator.

Re:Man...

[iamlucky13]

Super, hyper, and mega...you're mixing up your units there. Your generator is bound to accomplish nothing other than crashing into Mars.

An Interesting Star

[Nom du Keyboard]

This incredible speed likely resulted from a close encounter with the Milky Way's central black hole, which flung the star outward like a stone from a slingshot.

Close enough to accelerate it that much, yet not disrupt it in the process through tidal effects? An interesting star, to say the least. Too bad we can't observe it more closely.

Re:An Interesting Star

[Anonymous Coward]

*sigh*

Again, supermassive black holes have very little in the way of tidal forces. The gravity gradient is just not steep enough.

Googling it

[grahamsz]

Just go to google and search for

"1500000mph / c"

I still maintain that it's 0.002c or 0.2% of the speed of light

Am i missing something?

Re:Googling it

[Deep Fried Geekboy]

google for: 150000mph/c in percent

you get:

(150 000 mph) / the speed of light = 0.022367474 percent

(it's only a matter of time before we see the following in undergraduate mathethematical derivations:

'by google, e ** (i * pi) = -1'

etc)

Re:Googling it

[Anonymous Coward]

google for: 150000mph/c in percent You forgot a 0.

Re:Googling it

[HTH NE1]

It helps if you enter the right number of zeroes. 1.5 million, not 150 thousand.

One Down

[Nom du Keyboard]

So strong was the event that the speedy star eventually will be lost altogether, traveling alone in the blackness of intergalactic space.

One down, 200,000,000,000 to go.

Question

[Skye16]

I thought about this before (and I'm sure people much smarter than I have thought about it much sooner, but I haven't heard about it yet :) ): what if we could get a space probe to "catch" on to an asteroid (if it was large enough) and use its gravitational pull to essentially "drag" it out into deep space along with it? Wouldn't this be much faster than using its own propulstion?

Now it gets even more interesting; what if, in the far future, we have intra-gallactic travel down pat, but intergallactic is quite different. What if we could find a star that is going to do the same exact thing as this star and "latch on" to it, having it drag us waaaaaaaaay out into deep space (and by we, I mean a probe, a space station, whatever). Would it be possible? Useful?

Re:Question

[EvilTwinSkippy]

Um, no. While fast, most bodies like Comets take hundreds of years to reach the apex of their orbit. Sure, you would save on fuel, but those savings would be offset by having enough supplies around to maintain a small population.

The folks starting the Journey sure as hell aren't going to see the end of it.

Re:Question

[cnettel]

Even the travel Earth - Proxima Centuari would take a few millenia with this star. If we had any serious intra-gallactic travel, hitchhinking on a star like this at its speed would be purely boring.

Re:Question

[shrubya]

1: the problem with hitching a ride on a passing asteroid is that you need to match speed with it if you want to survive the landing. And if you can match its speed then you don't need its help any more, because that takes the same amount of energy as just going there yourself without the asteroid.

Maybe you could use enourmous bungee cords and rocket-propelled grappling hooks to latch on more gently, but if something snaps halfway through the process you'll be flung at high speed in entirely the wrong direction, probably without enough fuel to get back.

2: 1.5Mkps is fast in local terms, but for interstellar travel it's still a piddly 0.2% of c. That's thousands of years to get to the closest (planetless) stars, or billions of years for intergalactic.

To be blunt, human interstellar travel isn't going to happen, not by this or any other method, except a handful of probes. But absolutely nothing even remotely resembling Star Trek.

Re:Question

[xv4n]

...use its gravitational pull to essentially "drag" it out into deep space...

IIRC that's what they did to send the Voyager out of the solar system, using Saturn's pull to slingshot away the spacecraft.

Re:Question

[Dunbal]

The basic problem with your scenario is that if you can manage to get your space probe to move faster than the object you are trying to capture (if you have to catch up to it, you actually have to be faster than it), why would you need the object in the first place? Objects in motion stay in motion. If you can make it to that speed you will stay at that speed. You don't need to be "towed" by another object. You want to send a probe to deep space all you have to do it accelerate it enough.

Unless you mean shooting a low speed probe at an asteroid "head on", having it smack into the asteroid and having the asteroid carry the debris around with it forver. This is impossible. The energy involved in the collision would vaporise your probe. Look at it another way - even if it's a tangential shot, or whatever you argue. There is something called conservation of energy, mass, and momentum. To accelerate your probe to your desired speed you need to invest X energy. It doesn't matter HOW you do it, but you have to spend the energy. Now, you can spend it in the traditional way, over a period of days, weeks or months, gently accelerating your probe up to speed. Or you can spend it all at once when you collide with the asteroid. However your probe won't be able to survive receiving that much kinetic energy in such a small amount of time (the relative speeds would be HUGE).

It's like driving your fully gassed car on a flat road all day until the gas tank is empty, or dropping a match in the full gas tank. The amount of energy released is the same - it has to be. But in one scenario you survive, in the other you don't.

I'm sure others will correct me if I am wrong, my training lies in a subspecialty of biology, not physics. But that's how I understand it.

That depends on where you're standing.

[AltGrendel]

Speed is relative, after all.

Re:That depends on where you're standing.

[slide-rule]

> Speed is relative, after all.

True, but in terms of trying to make sense of the orbital mechanics of things (and for sake of being a minor pedant), one generally can make a safe assumption of reference point being that which exerts the dominant [gravitational] influence. (E.g., satellites with respect to the planet, planets w.r.t. their star, a star w.r.t. the galactic center). Unless more precisely worded, it's probably safe to assume the question was w.r.t. the galactic center in this case.

milky way munching stars and galaxies

[peter303]

I thought last year they found four "drawf" galaxies in vicinity of the Milky Way, about to be absorbed.

The big Kahuna of course will be the merger with Andromeda about two billion years hence. Our mutual gravitational attraction is drawing us together. In practical terms, both galaxies are essentially empty space. However Andromeda will grow from its present size in the sky of six full moons (192 arc minutes; but just a faint smudge) to fill the entire sky. See the collision simulation here.

Re:milky way munching stars and galaxies

[kevlar]

Two galaxies colliding is about as spectacular an event as watching grass grow. Galaxies are very spacious; there probably would be no kinetic interaction between the two if they were to "collide".

Re:milky way munching stars and galaxies

[corngrower]

there probably would be no kinetic interaction between the two if they were to "collide".

I would bet that there would be a number of stars in the galaxies that would have their motions markedly changed. You'ld probably have a number of stars being scattered around and exiting the galaxies at high velocities relative to other stars . There may even be an actual collision or two.

Re:milky way munching stars and galaxies

[perrin]

It is true that the chance of starts actually colliding is very remote, but the danger for life is mostly clouds of interstellar gas colliding, smaller stuff being sent in every direction, and worst of all, the chance that the supermassive black holes in the center will attract each other and collide.

If the black holes in the center of the galaxies collide, I doubt any living things could survive in either galaxy.

Re:milky way munching stars and galaxies

[RocketRainbow]

There is a great way to visualize this. Take two globs of play-dough about golf-ball sized. Or golf balls if you're less inclined to play with the play-dough afterwards. So these globs - they're stars. Put them at their correct distance so as to maintain the scale (guess the average distance of stars). You're wrong. They're 17 000 km apart. Now imagine they're galaxies. No, this isn't a trick question this time. You don't even need a partner to hold the other glob. They're about a metre apart. So, yeah, galaxies collide. But stars don't. However, if you watch some simulations of colliding galaxies, you'll see that they are very well stirred up by the event. Unless the collision is a very fast one and the galaxies' spins are properly aligned, the galaxies end up different shapes. They may merge and if not, there will probably be great trails of stars between them (looks great!) I love it when galaxies collide! I could talk about it all day (see my user description).

Weapon Testing, Anyone?

[Trifthen]

Who wants to be the first to claim this is simply a huge plasma burst fired by an even larger weapon? Maybe it's just some alien race out there who wants to illustrate that they too, emjoy blowing things up with oversized guns. ^_^

Re:Weapon Testing, Anyone?

[Aero]

Maybe it's just some alien race out there who wants to illustrate that they too, emjoy blowing things up with oversized guns.

Either that, or the gods are playing Katamari Damacy again.

overheard

[Anonymous Coward]

"we've named the star fiorina..."

Now where is....

[Anonymous Coward]

...Korben Dallas when you need him?

Let me be the first to say...

[fizban]

"Fore!"

Radio Telescopes Tuning in...

[EvilTwinSkippy]

Radio telescopes tuning in keep hearing murmurings about how the Galaxy was not taking the Star's ideas seriously, so it's going off to start its own Galaxy.

There's more

[Nom du Keyboard]

Not only is it moving really, really fast. But reports indicate that it is an anti-matter star, cutting a thin chord through the edge of Known Space.

RFI

[CmdrGravy]

I once read a book about some 'intelligences' which could live in Stars, unfortunately they didn't like each other very much and would constantly fight.

As part of one of these fights one of the intelligences caused the Earth to accelerate in the same way this star is accelerating on a course which took it out of the Milky Way and into empty space. Eventually it was travelling so fast that nothing from the solar system could possibly ever make it back to the Milky Way.

It was told through the eyes of an unfortunate man who kept on being cryongenically frozen and unfrozen over a period of millions of years as the planet became ever more chilly and isolated from everything else.

It was a great book and I wish I could remember what it was called since I have wanted to re-read for a while now.

Re:RFI

[GodLived]

It sounds like Frederik Pohl's The World at the End of Time.

Re:RFI

[CmdrGravy]

Fantastic, thanks I have been looking for that for ages. Cheers.

What a coincidence...

[dohboy]

my swivel chair revolves around a black hole.

Actually it's standing still

[objekt]

The rest of the universe is moving.

It's all relative.

Re:Relative speeds [clarification]

[FirienFirien]

First line should read "Your first comment is odd - the milky way is the galaxy.

*smacks back of own hand with ruler for bad grammar. Twice.*

Physics question...

[Anonymous Coward]

So, if the black hole catapulted this massive object (~3x our sun) to such speeds (~1/600th speed of light), and energy cannot be created or destroyed... Then how much energy did this star take from the black hole around which the milky way spins? Furthermore, does that jeopradize our pivot point -- will the milky way spin with a larger diameter now that the forces pulling us in have been reduced?

Seriously spooky.

the original poster stole his description

[Anonymous Coward]

Did anyone else notice that the following sentence is right out of a Wired News article on the same topic?

"The first-of-its-kind finding not only confirms an earlier theory about the existence of such speeding stars, but also reinforces the notion that the Milky Way spins around a black hole."

Nice plagiarism, fenimor.

More info

[Woogiemonger]

I found more info on this, including more numbers, from this Reuters article. And by the way, it's moving at about 0.002c, which is pretty fast for something so huge. However, if you really want to be impressed, the gas in blazar jets moves at about 0.999c.

Re:More info

[aspx]

Imagine the havoc this star would cause if it passed through our solar system. It wouldn't even need to hit a planet.

Explanation

[af_robot]

For those, who didnit get it.
Puppeteers are alien race from novel "Ringworld" by Larry Nivel. They were moving their home star system to a new galaxy to escape from the Core explosion.

Re:Explanation

[huge colin]

...although you might not get great Google results with "Nivel" -- it's actually Larry Niven.

Re:Explanation

[Anonymous Coward]

>> ...although you might not get great Google results with "Nivel" -- it's actually Larry Niven.

Google: "Did you mean: harry navel?"

No, Google, I didn't. :)

Re:Explanation

[Crass Spektakel]

The puppeteer-stories where also part of some collections and mags of Isaac Asimov who was always eager releasing good scifi-collections.

Wow who knows...

[McNihil]

Perhaps this is some cicvilization that forced it to happen so they would survive in the longrun. In any event it should be VERY easy to spot such an event because they wouldn't be a dime a dozen. Also much cheaper to make the entire start system and keep the start ship vessels (habitable planets) with them at all time. Note to future generations: Keep earth as intact as you possibly can so we also can do this when time comes.

Quick Question for those who have RTFA

[EvilTwinSkippy]

When they quoted the mass of the star, did they take into account General Relatively. Namely, that something traveling that fast increases in mass as time slows down.

Re:Quick Question for those who have RTFA

[eddievalentine]

Who is General Relatively?

Re:Quick Question for those who have RTFA

[EvilTwinSkippy]

I think he is in the same branch of the military as General Panic and General Failure.

Re:Quick Question for those who have RTFA

[darthv506]

It's travelling at 1/500 of the speed of light... so for the most part, you can ignore relativistic effects. And it's Special Relativity that deals with time dilation and relativistic mass, not GR.

Its the Necromongers!

[Evil W1zard]

They are coming after Vin Diesel... In other news a group of 20 people dressed in full Nike running suits just committed mass suicide in hopes that the ETs traveling in the wake of the asteroid take them to their home planet of Stoopidia.

Re:Its the Necromongers!

[Anonymous Coward]

Well if they're coming for Vin Diesel then I'm all for 'em.

Now if they can just take Arnie, Jean Claude Van-"Brain"-Damm(age) and the rest of 'em it will be even better.

Finally if they've brought Bruce Willis a new vest they definitely get my vote. Definitely.

Naww - Cueball

[wowbagger]

This isn't the Fleet Of Worlds - that would be a set of planets with fusion reactors in orbit.

Obviously, this is Cueball- and woe betide anybody who attempts a landing there - you won't be pissing a Monolith off, you will be converting yourself (and a chunk of the antimatter planet) into energy.

Black hole?

[The One and Only]

I thought it was well established that at the center of the galaxy there is a planet, that God is on that planet, and that (as it is becoming abundantly clear), he needs a fucking starship!

Re:Black hole?

[CCRancor]

I take offense at the notion that God would be affiliated in any way with a black hole - we all know God is a straight white guy!

Re:Black hole?

[classical piano]

But of course the only way to get him one is to pass through the barrier, and I can only think of one crew with the capabilites.

What about relativity?

[aiken_d]

From the SDSS J090745.0+24507 Daily News:

Universe Takes Off
The entire rest of the Universe suddenly accelerated to over 670km/sec and is fleeing our vicinity at an astonishing rate. In fact, the Universe seems to have decided to move a large region of intergalactic space into our vicinity, which will have a dramatic negative effect on property values.

Scientists are at a loss to explain the sudden move by the entire Universe, but have assured the Theocracy that the subspace ether is still intact and that our sun is still planted firmly in exactly the same spot it always has been. The scientists did say that the sudden movement by the entire Universe may have stressed the subspace ether, and that concerned citizens should at least double their daily offerings to Zugbat lest our sun lose its attachment to the ether and be sucked across space with the rest of the Universe.

There will be an execution of two atheists who suggested that our sun had begun moving at a high rate of speed, and not the rest of the universe. See page 6.

Cheers
-b

Re:What about relativity?

[Dunbal]

In other news...

Our scientists have announced that they have almost compeltely ironed out the wrinkles in the new warp drive which began testing last week. The lead scientist, Zhuk'Urg, stated in reference to the project "Our test has been an almost complete success and we should be able to move our solar system nearer to the galactic center real soon now". No one could be found to comment on the suspicious blue screens visible on all of the computers at the research institute.

Re:What about relativity?

[jonhuang]

The remarkable thing about all this is that the above humorous description could be.. correct.

it's completely relative whether we are moving or everyone else is moving, right?

Re:What about relativity?

[pclminion]

Motion is relative but acceleration is not. Although it is valid to choose the star as the frame of reference, it is a non-inertial frame and thus would require the introduction of fictitious forces to explain the behavior of the rest of the universe.

If I were working the equations, I would prefer a reference frame which did not introduce fictitious forces on a universal scale.

Didn't we just read about this?

[ScentCone]

I believe that the black hole that is HP's board of directors has sent the star Carlis Major on a very high-speed path to a Different Place.

Collision!

[Anonymous Coward]

Any other stars in its trajectory? That'd be cool!

fast, but not fast enough to notice.

[Ruis]

This thing takes about an hour to move the distance equal to it's diameter.

as seen on T-Shirt Hell

[Anonymous Coward]

I spent the night in Paris

Want to see the video?

Where is it going in such a hurry

[sxmjmae]

I wonder where the star travel to.

Will it still be burning by the time it gets a new galaxy?

It is star that is expected to go nova or turn into a brown/white dwarf? I wonder what will happend to the star when is not longer confined a Galaxy. Will the lack of other graviational bodies have an effect on its life/death?

Mixing Units Of Measurement (And Time!)

[BRock97]

at a speed of over 1.5 million miles per hour (670 kilometers per second)

No offense to the person who submitted this article, but do you think you could refrain from mixing your units of measurement (or time, for that matter). From a readability, it is much harder to following "x miles per hour (x meters per second)". People do this all the time and it drives me nuts! Suggestions would be:

• 1.5 million miles per hour (416 miles per second)
• 1.5 million miles per hour (2.4 million kilometers per hour)

Not trying to be an ass, but it just makes more sense when you read it. Thanks.

Re:Mixing Units Of Measurement (And Time!)

[Anonymous Coward]

Not trying to be an ass

You succeeded, however.

Hey, laugh! It's a joke, son! :-)

Re:Mixing Units Of Measurement (And Time!)

[BRock97]

In the immortal words of Peter Griffin:

"Touché salesman..."

Re:Mixing Units Of Measurement (And Time!)

[Bisqwit]

> at a speed of over 1.5 million miles per hour (670 kilometers per second)

I think this was fine.
"x mph" is for your average american person who talks in imperial units (the core audience of Slashdot readers?) and
"x km/s" lets science-oriented people understand how the speed relates to the speed of light (which btw, is about 300000 kilometers per second - the relativistic effects are still almost neglible).

Wow must have been the Sony Star

[Momoru]

star three times bigger than the sun, leaving our galaxy at a speed of over 1.5 million miles per hour (670 kilometers per second).

Thats only 1 million miles per hour faster then a UMD flying out of a Sony PSP ;)

Please tell me it was

[gardyloo]

Richard Simmons!

PA Cops

[Anonymous Coward]

I can see them salivating at the thought of the amount of revenue they can generate by ticketing this star.

Against a Dark Background

[Anonymous Coward]

Damn Lazy Guns.

Trust me, I'm a rocket scientist

[starglider29a]

Short answer: Yes, but...
Longer answer: "The catch" is the catching. Imagine 'skitching' on a bullet train...

1. Get maximum benefit by standing still, but suffer maximum acceleration. You'd need a HUGE shock chord.
2. Get minimum accerelation by matching the speed, minimize the shock, but it costs you more energy to match the speed at an acceptable velocity difference.

I know yer asking about "the gravity of the asteroid", but most asteroids gravity is so low that you would have to be nearly their speed to even get a boost.

*** IF *** we had a tractor beam that we could feather in the attractive, it would work. But then, we could just aim it at Mars, wait 23 minutes and HANG ON! We could also 'lasso the moon' at moonset and paraglide up into space.

And leave "intergalactic planetary" to the Beastie Boys. At that rate, the outcast star will still take a BILLIONish Years to get to Andromeda.
-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_
"The laws of orbital mechanics are as unforgiving as the laws of Supply-Side Ecomnomics"

Can't help but wonder

[Sefi915]

Are they tuning these 'scopes correctly?

I'd bet real latinum that what they detected was a Kemplerer Rosette!

unanticipated event?

[apostrophesemicolon]

so does this mean there can be things - stars, asteroids, any heavenly objects - flung towards earth or our solar system, so sudden that we wouldnt be prepared, or at least know before it's too late? Or would we know beforehand as potential threats are setting up?

What if there were planets orbiting it?

[Blarfy_Snarflepoop]

Warning: I know next to nothing on this topic.

If this star had planets orbiting around it, as it got flung away from the black hole - would they get stripped away, or would they stay with the star?

Just curious.

Re:What if there were planets orbiting it?

[EvilTwinSkippy]

Depends on how close the system came to the large gravitational mass that flung them off. If they passed really close, and the pull of the larger body exceeded the pull of the star, then yes, a lot of stuff would transfer orbit to the larger body, or been slingshotted off into space.

If the approach wasn't that close, then the planets would still have been a lot more attracted to the "traveling star" than anything else. Their orbits may have been altered slightly by the influence of the larger mass, but they would have stayed.

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[account_deleted]

Comment removed based on user account deletion

I'm curious

[novakane007]

I wonder if the Star had planets. What would have happened to the solar system that surrounded the star? It would be interesting to see an animation of what this process looked like. If any of you Astro-Physics majors want to try and describe this for me that'd be great.

Uh oh

[Anonymous Coward]

"leaving our galaxy at a speed of over 1.5 million miles per hour"

What does it know that we don't?

That's no Star!

[Keck]

it's Carly Fiorina being ejected from HP .. why they didn't do this sooner probably only comes down to how long it took for the board members to get their Meeelion dollars in bonuses for the Compaq merger..

Ejection

[HarveyBirdman]

I'd hate to mess with the bouncer that did this.

Comment removed

[account_deleted]

Comment removed based on user account deletion

Re:Inertia & Momentum - Star Stampede

[m0smithslash]

How do we know that the star is being ejected from the solar system? According to relativity, to an observer in the galaxy, a star being ejected from the galaxy looks the exactly the same as using the star as the frame of reference and the whole of the milky way galaxy is moving away from it. Since we didn't actually see where this star was coming from, the star could have been holding still for a long time while the galaxy far,far away came stampeding past like the wildebeast stampede in Lion King. To us stuck here on earth it would look exactly the same either way. So its not so much tht the star is being ejected, but that it survived the stampede.

MOD PARENT UP

[Spy der Mann]

"Informative".

Thanks for the info on quasars :) Since I'm not an astronomer, my knowledge regarting this topic is limited.

Galactic Patrol

[AndroidCat]

Nah, I get the impression that this is the galactic version of Cops where some drunken redneck is running from the police in a demolished car riding on the rims. Pretty soon we'll spot red and blue flashing pulsars in hot pursuit.

Bad stars, bad stars! What ya gonna do when they come for you...?

Astronomy / Math question

[popo]

Assuming that this star was accellerated to this speed by slingshotting around a supermassive blackhole (like the one at the center of our galaxy): How long would it take at this speed to move from the center of the galaxy to the edge of the galaxy?

And more importantly, how much advance warning would we have if some star shot towards us from the center of our galaxy at a similar speed?

Re:Astronomy / Math question

[chinton]

Quoting a related space.com story:

It is travelling at twice the speed needed to escape the gravitational clutches of the galaxy. About 80 million or 100 million years from now, Brown said, the star will exit the galaxy and become a lone wanderer of intergalactic space.

Re:Astronomy / Math question

[spanklin]

On average, the stars in our Milky Way are moving at about 1/3 of this velocity (the outcast star is moving at 670 km/sec, the Sun is moving at 220 km/sec).

The nearest stars to the Sun are several parsecs away, so even if the nearest stars were all approaching us at 220 km/sec it would take them about 25,000 years to make it to the Sun's present location.

If you want to worry about something, you should be more concerned with near earth asteroids than rogue stars heading for us at ~700 km/sec.

Relativity?

[Viking Coder]

Correct me if I'm wrong - but isn't it equally valid to say that our entire galaxy is fleeing away from this star? From the point of view of a planet (yeah, right) orbiting this star, it would seem as though they were stationary, and the entire milky way was fleeing from them.

Right?

Wow, it's leaving fast.

[FrankieBoy]

Must have found about Bush's re-election.

This proves it!

[Anonymous Coward]

I told you the whole fucking galaxy is going down the drain!

This is old news...

[Anita Coney]

Eminent scientist Dr. Ritchie Blackmore already proved the existence of such a fast star in his seminal treatise "Machine Head." If I remember correctly it was somewhere in the first chapter.

Moving

[sunjin]

Just remember that with relitivity involved it could be the galaxy that is moving. The star could have just stopped.

Re:Moving

[eutychus_awakes]

While witty, that scenario doesn't hold up if you consider that either the star or the galaxy had to undergo a (relatively) brief period of acceleration in order to exhibit the behavior we currently see. The probability of every star in the galaxy except this one undergoing that kind of acceleration is minuscule - however, the probability of one star meeting the conditions of the proposed hypothesis is quite high.

That's how we solve these kinds of paradox problems in relativity. The classic "Twin Paradox" is solved in a similar manner. For those who need a refresher, it is the 'paradox' whereby one twin takes a trip at some substantial fraction of the speed of light and returns to find the other several decades older than himself (or herself) due to the time dilation effects encountered during the trip. The paradox is: From the point of view of the twin on the trip, it is the twin on Earth and everything else that ends up going very fast. Why shouldn't they be the ones to experience time dilation? The answer is, a deliberate acceleration is applied to the twin on the spaceship (reaction mass burning, converting energy to momentum). This defines the reference frame for the experiment, resulting in the correct application of the time dilation effect.

For our wayward star, its reference frame was defined by its proximity to our galactic center, and the probability that a super-massive black hole smacked it out of the galaxy's gravitational hole.

goodbye to neverland

[chalkoutline]

"astronomers have discovered a star leaving our galaxy at a speed of over 1.5 million miles per hour" I agree, Michael Jackson's court case is indeed the final demise of his career.

Re:Relative speeds [clarification]

[Ohreally_factor]

Wow! You're your own gammar nazi!

Screw you guys, I'm goin home.

[gelfling]

That is all

Let's be careful.

[Anonymous Coward]

It might have been shot into space with bug plasma. We should send the Fleet & MI to investigate.

Out of the physorg tarpit, original release...

[argent]

Why don't the /. moderators quit pointing people to the physorg tarpit. The never credit their sources or provide links to them...

http://cfa-www.harvard.edu/press/pr0505.html

Black holes have no hair

[Ohreally_factor]

'cause black holes don't have a size limit.

Do you mean that they don't have a mass limit? Because they definitely have a size limit. They're 0-dimensional.

Or are you thinking of the Schwarzschild radius?

Re:Black holes have no hair

[Fjandr]

Not an actual scientific convention, but I'd describe them as -3 dimensional. :)

Re:Black holes have no hair

[Anonymous Coward]

Actually, according to M-theory, black holes are not 0-dimensional at all, but would have a diameter equal to the Planck length (1.6 * 10^-35 meters).

Re:Black holes have no hair

[Anonymous Coward]

A black hole needn't be a singularity. A very dense body can have both a schwarzchild radius and positive volume, provided it is not too massive. This follows from the fact that the scharzchild radius encompasses a non-zero volume. If you decrease the mass, the SR decreases and the singularity "re-inflates" into regular 3-space. So either you get a singularity with a zero S.R. at some point, or you must have black holes that are not singularities.

Either that or....

[Schwarzchild]

it's just a Really Really Big Spaceship. Really Big.

Re:Either that or....

[Anonymous Coward]

Hey, what's your radius?

Re:Either that or....

[bill_mcgonigle]

it's just a Really Really Big Spaceship. Really Big.

Why not use a solar system as a big spaceship, if you can motivate the sun to move?

You're going to need lots of resources and power for your trip to the next galaxy. In fact, this may be the only way to do it.

pretty inefficient.

[NickGully]

It's still only getting 64 miles per ton of hydrogen

So long and thank for all the mass

[spywarearcata.com]

I guess since this object is leaving our galaxy forever our galaxy has a kinetic energy leak. That's sad.

Scifi Story

[jmoo]

I can't remember its name but this reminds me of story I read some years ago about a human colony in another solar system that has its star and planet pushed out of the galaxy at great speed. In the story it was not a black hole but some kinda superbeing that pushed them off.

Deathstar!

[east coast]

Vader is back... and boy, is he pissed!

And in other news

[Mac73117]

A little know intergalatic terrorist organization has claimed responsibility for the plasma burst observed. Secretary of State Rice could not be reached for comment. However, President Bush is ramping up space exploration with the intention of invading the terrorists home system.

REJECTION!

[Anonymous Coward]

GET THAT SHIT OUTTA HERE!

Re:REJECTION!

[eggoeater]

This is a test.

System-less

[Anonymous Coward]

That is, time in the moving system (the star) will be observed...

I'd reckon that after a slingshot pass around a black hole, if the star (pair) had a planetary system orbiting around it (them) that the planets were either captured, consumed, or scattered away by the black hole.

Looks like

[Ohreally_factor]

Someone went and taunted the happy fun ball.

Or....

[fleener]

Or it's evidence of the opposite, that galaxies are not coalescing, but expanding.

Claim your vacation time in terms of distance

[Polarism]

traveled.

Demand payment for the millions of miles you travel each year.

Too far away for that

[davidescott]

Since they indicate that this has or is leaving the Galaxy I assume it is already pretty close to the edge of the Galaxy in which case it is probably much to far away to use that technique. It would be like trying to judge the speed of a bullet from the perspective of the individual holding the gun.

Re:Too far away for that

[altstadt]

... I assume it is already pretty close to the edge of the Galaxy...

Spock: He is intelligent, but not experienced. His pattern indicates 2 dimensional thinking.

Not intended as a dis.

It's going to be a bitch finding your ball

[Anonymous Coward]

I hope you don't need a mulligan, and I sure don't want to see how much you spend on balls each round...

Meanwhile, at the alien overlord weapons lab

[IronChefMorimoto]

G'nok: "Dammit, G'nariak -- I told you to calibrate the Star Destructor targeting computers yesterday!"

G'nariak: "Sorry, sir. I had to take the wife to her obstetrician yesterday during lunch; I was in a rush; it won't happen again."

G'nok: "Damned right it won't. The Earthlings SAW the Star Destructor test! They were supposed to EXPERIENCE the test!"

G'nariak: "Again, sorry sir -- I'll make it up to you."

G'nok: "You damn well will -- we have to explain to G'tariak why his vacation home at the edge of the galaxy isn't there anymore. Dumbass!"

IronChefMorimoto

nitpick

[bluGill]

Kelvin is not a relative scale and thus it has no degrees. Celsius and Fahrenheit are relative scales and have degrees.

Overall your point is correct.

Re:nitpick

[Anonymous Coward]

just to add, kelvin is based on absolute 0.

0 degrees celsius is defined the temperature water turns into its solid state, 100 degrees celsius is defined as the temperature water turns boils at sea level.

farenheit is scaled off the temperature mercury turns to its solid state.

a 1 degree increase in celsius matches a 1 "degree" increase of kelvin, farenheit is all screwed up in how it scales (blame the english).

0 degrees kelvin == -273 celsius == -459 farenheit

Re:nitpick

[Anonymous Coward]

An anonymous karma whore?? uh, wtf?

Re:nitpick

[belroth]

Absolute zero is 0 Kelvin.
Not 0 degress Kelvin.

It must be the Nemesis

[roman_mir]

we are all doomed. Doomed I tell you!

Obrigatory Portishead reference

[praedictus]

Wandering star
For whom it is reserved
the blackness
the darkness
forever...

Re:Inertia & Momentum - Star Stampede

[myowntrueself]

"the star could have been holding still for a long time while the galaxy far,far away came stampeding past like the wildebeast stampede"

So exactly how many stars do you need for a stampede? Is it three or more? Is there a minimum speed or what?

;)

That was the good news

[carcosa30]

The bad news is it's heading straight for us.

Wait, the Sun moves at 3/4 of escape velocity?

[kalirion]

Sun through space: around 155 miles per second

The star moves at 417 miles per second, which is double the galactic escape velocity. That means the Sun moves at 74% of the galactic escape velocity!

But wait, shouldn't escape velocity be different depending on where in the galaxy you're located? If you're at the very edge you'd need less velocity to escape (since there's less desceleration) than if you were near the center, right?

Re:Wait, the Sun moves at 3/4 of escape velocity?

[khallow]

But wait, shouldn't escape velocity be different depending on where in the galaxy you're located? If you're at the very edge you'd need less velocity to escape (since there's less desceleration) than if you were near the center, right?

Indeed you are correct. As it turns out, the star is considerably further away than the Sun is. From the article I just linked:

The star is catalogued as SDSS J090745.0+24507. It is currently in the galactic outskirts, about 195,000 light-years from the center, and it's a similar distance from Earth. The path suggests it did not come from any other nearby galaxy nor is it headed toward one, Brown said in a telephone interview.

So the Sun is roughly 25,000-30,000 lightyears (according to the sources I googled through) from the center of the Milky Way while this star is eight times that distance.

Dengejaa Uveso

[Scarabaeus]

... that's the name of the black hole in the center of our galaxy, milky way. At least according to Perry Rhodan.

Attribution

[Pfhorrest]

Thought I'd mention for those curious, that's from the old cartoon Animaniacs. Let me see if I can Google a complete transcript:

Hey, I'm Feeling Lucky works:
http://alpha.lasalle.edu/~smithsc/Astronomy/Yakko_ Universe/yakkos_universe.html

Clearly it was trying to go back in time...

[zapp]

... by flinging itself around that black hole.

Looks like Kirk was full of shit.

Trouser Measurments

[Anonymous Coward]

Actually, I find it sounds much more impressive when I announce the measurements of my trouser contents in centimeters.

"I'm serious! It is ten centimeters! But you'll have to sleep with me to confirm it."

Will the star escape the local group?

[purplejacket]

SDSS J090745.0+24507 will escape the galaxy; will it also escape our Local Group of galaxies?

Further, the Local Group of galaxies is moving at about 600 km/s (relative to the cosmic microwave background) in the direction of the Hydra-Centaurus supercluster.

Will SDSS J090745.0+24507 end up there?

Why do I love antagonizing math/physics geeks?

[Anonymous Coward]

Could it be because you poor sods have the sense of a humor of a doorknob?

This could be interesting...

[CrixelGarten]

It would be interesting to see where this thing is going. If it hits anything, it would see that it's going to splatter like an egg against a brick wall, but much more violently. Wonder when we'll see that?

An analogy

[starglider29a]

Most everything said above this is true-ish, plus or minus, give or take. But let me try an analogy to dispel the "slingshot" misnomer.

Analogy:
A rollerblader with a cane is at the top of a large bowl shaped parking lot with a light pole in the middle. A motorcyclist is driving clockwise in circles around the light pole. The sk8r coasts down the hill and hooks the light pole making a sudden right turn. As he heads out he hooks the biker from behind and makes a sharp right turn. Skater careens up the bowl and shoots over the edge with big air to fall down in front of a buddy with a video camera. Jacka55!

Ok, sk8rboi left the bowl faster than he started. How? He got the added speed from the biker. Without the biker 'orbitting' the star, the sk8r would have hit the edge of the bowl with very little velocity left.

Galactic centered Black holes allow stars to orbit them very very fast, even in circles. But a star that falls IN past the black hole and then whips around an already-orbitting star get the total of falling into the center PLUS the speed of the orbitting star.

You don't get a slinghot with only one star, even a black hole. That whole thing with the Bird of Prey and the whales is just wrong.

Starglider29a
If time is money, does the Lorenz Equation dilate money as well?

Re:An analogy

[another_henry]

That's a pretty good analogy.

The gravitational assists carried out by probes in our own solar system work in a similar way but don't usually involve swinging around the sun. Instead the idea is to come up behind another planet, e.g. Venus, as it travels around its orbit. As you approach the planet from behind you experience an attraction causing you to accelerate. You then move out away from the planet, while still remaining behind it (w.r.t. its direction of travel) until you are pretty far away and outside most of its gravitational field. This results in extra momentum for you, and less momentum for the planet - it slows slightly in its orbit.

What I don't understand is a different type of gravitational assist manoever. I have read that it's possible to get a great boost in velocity by approaching close to a large body, e.g. the sun, then burning a rocket engine near the time of closest approach. Somehow the delta-v from the rocket is multiplied several times. Can anyone explain how this one works? Or is it bullshit?

Re:Inertia & Momentum - Star Stampede

[Wraithlyn]

Well they say its trajectory is coming pretty much directly from the centre of our galaxy, which supports their galactic black hole slingshot theory.

It's still possible that it's an extra-galactic object that just happened to intersect with the centre, but that requires us to assume a large coincidence, and we know what Occam has to say about that.

Sorry, the jerk is correct.

[Ryan C.]

There's a subtle distinction between acceleration and what most people think of as the force of gravity/acceleration.

The problem in your rocket and centrifuge analogies is that they don't actually accelerate all the parts of the system evenly. Someone accelerating due to gravity in free fall can accelerate at 1000G and feel nothing. If your rocket was individually coupled to each and every atom of the astronaut, there would also be no problem for the astronaut.

The problem is when you introduce a floor, chair, whathaveyou. Now there is a normal force due to electrostatic forces (solid object) but it only acts on the contact surface. So it pushes on your butt and in turn all the parts of your body push back against the acceleration (or inertia, depending on your mass frame) of gravity/rocket/centrifuge. So what kills you is the difference in acceleration between your body parts and the floor: delta a, or jerk.

Re:Sorry, the jerk is correct.

[jaoswald]

The term "jerk" is too specific; it is usually the *time* derivative of acceleration.

What you are talking about is a *spatial* gradient of *force* or *pressure* which would be represented by a *stress*.

Re:Inertia & Momentum - Star Stampede

[m0smithslash]

Again its all relative. To the average slash dot reader, two stars headed your way at high speed would look like a stampede. Of course, to the stars, it would appear they were being attacked by a very small bug and they would spend the rest of eternity trying to figure out what they had done to deserve such treatment. The relative speed of a stampede is computed based on the overall relative speeds of the stampedee and the stampeders. Someone with more free time than I could work out the math.

Delving into Fantasy...

[Biomechanical]

This puts me in mind of the sun orbiting Great A'Tuin - even though that sun is much, much smaller.

Does the star occasionally become obscured by an odd, giant turtle shaped object? Is it moving in a slightly screw-like trajectory? Does an elephant occasionally lift a leg to let it pass?

Terry Pratchett, this star's for you. :)

Re:Inertia & Momentum - Star Stampede

[m0smithslash]

Just because its unlikely that doesn't mean it won't happen. The chances of winning a lottery are millions to one against, yet someone does win. Also, its highly impropable that life exists on any given planet. Yet, here we are reading slash dot (notice lack of reference to intelligent). And it dangerous to generalize from a specific instance.

Did we at least aim it at the Andromeda Galaxy?

[Anonymous Coward]

That ought to wake the aliens up!

uh-oh! What does it know that we don't know...?

[Anonymous Coward]

Road Trip @ Ludicrous Speed !!!

YA Gravity Assist

[starglider29a]

Mythbuster: "Delta-V" is a function of amount of propellant burned for a given type of engine. Period. It is not affected by velocity, orbital geometry.

But, I know what you're saying. It's not bullshit. But there are some misnomers and misconceptions. I will try to expound on what I know you are saying.

• In general we are talking about a probe escaping Earth. Say, off to Saturn...
• After that, we are escaping the sun, as in Pioneer and V'Ger (before the upgrade ;-). In those cases, maximum velocity for minimum propellant is the goal.
• Orbits whose ellipses are the same major axis have equal period.
• High eccentricity orbits reach out farther than circular orbits of same major axis/period
• High eccentricity orbits require higher velocity near the planet/sun
• Until you hit escape velocity (a parabola or hyperbola) you are in a long ellipse

If you want to get a probe "out there" you want to burn at periapsis (Earth: perigee or Sun:perihelion). That leaves the peri at the same point and raises the other end. Do that enough times and you get escape on the last pass. Delta-V at any other point on the orbit will raise the peri and lower the apogee/aphelion. Propellant wasted.

Often, satellites will burn at perigee, orbit around and repeat. This allows the same amount of propellant to get your there, but without the mass of a larger engine/structure. Smaller motor more often is more efficient, just takes longer. Nothing is free.

In short, you don't get more Delta-V, but you get it where you want it.
--
"Illustrative Myth: Once you are out of earth orbit, you are halfway to anywhere."

Re:YA Gravity Assist

[another_henry]

Thanks for the info. Looking forward to learning a bit more calculus so I can handle some orbital mechanics :)

Yeah, thats pretty fast...

[Anonymous Coward]

a speed of over 1.5 million miles per hour

That's pretty fast, relatively speaking.

In related news...

[Anonymous Coward]

Poop Flung From Chimp at High Speed

Mod my answer above (grandparent) back to zero

[Somegeek]

OK, I went and looked it up, and wouldn't you know it, Tired and Emotional is right. Maybe T&E is a real astronomer.

Anyway, it turns out that all of my assumptions about how the gravitational slingshot works were wrong. Go figure. It turns out that the motion of the planet during the period of gravitational influence (or lack of in the case of this black hole), is the where the speed boost comes from (or doesn't, in the case of this 'stationary' black hole). I always figured that you got the speed boost from being pulled in by the object's gravity and then somehow kept the extra speed on the way out. Doesn't make much sense in hindsight.

Thus my comment about the stars slingshot being similar to our spaceprobe slingshots was wrong. As was my comment about the binary not being critical - as T&E posted above it is probably the only way it could work.

I should have just stuck to saying that you can have really really big black holes.

Good description of the gravitational slingshot at the wikipedia : http://en.wikipedia.org/wiki/Gravitational_slingsh ot

So, please mod my grandparent response back down to oblivion. Thanks. I will stick to geekdom now and try and avoid orbital mechanics.

Puppeteer World

[Anonymous Coward]

They've discovered the Puppeteer home world.

Wrong...

[HermanAB]

it is the galaxy that is moving.

Astronomer: Warren Brown

[aagha]

The astronomer who made this discovery turns out to be my brother-in-law.

What I find to be fascinating (as does he) is the massive amount of press coverage this story is getting. He's already been interviewed by the BBC, CBC, a French science magazine, and the list goes on and on.

I do think that the whole thing is very interesting, but I do wonder what it is about something three times the size of the sun moving at over one million miles an hour that makes people interested in something like this. Bizarre!

Uh guys...

[Alpha_Traveller]

Maybe it just looks like it's being flung out of the galaxy...
Alternatively it could be US flying at great speed toward to the Black Hole.

How fast?

[amling]

.002236 c

Re:Inertia & Momentum - Star Stampede

[hawk]

> How do we know that the star is being ejected from the solar system?

It wasn't ejected. It voluntarily stepped down, just like Fiorina :)

hawk

I warned them!

[hawk]

I tried to warn NASA about this, but Noooo, they wouldn't listen, and opened fire on Mars with those "probes" anyway.

I'll get the last laugh, but it won't last very long unless i get some really good time dilation going. . .

hawk

Re:Inertia & Momentum - Star Stampede

[m0smithslash]

I wonder if she will be moving as fast when she hits the exit.

Re:Cheap

[sail4evr]

I would hazard a guess that any change in the shape or direction of the galaxy and hence its stars, by interacting with another would cause orbital shifts among every stars orbiting bodies. By using our example of life on this planet...most any orbital change would be cataclismic to life as we know it. On the plus side new opportunities for life might occur.

Re:Relative speeds - look at the units!

[verayh]

1.5 million mph is equivalent to 416.7 miles per second. And for the correct SI units, its about
671000 m/s
or 2.4 million km / hour

So, its less than 3 times as fast as our sun's journey through space.

Don't you just love it when people amaze you by adjusting the units! Nevertheless, its an interesting phenomenan. Its still got a hefty pace.

Outer planet orbits may be perturbed

[Anonymous Coward]

I've always wondered why the orbit of Uranus should be so markedly different than that of the other planets (sometimes it is closer than Pluto, other times it's further away, and it dips above and below the plane of the solar system).

Maybe such a collision has already occured long ago, and only the gas giant's orbit was slightly perturbed (because it was the only planet out of phase with the others at the time)?

BIG NATURAL PHENOMINON!

[Anonymous Coward]

AAAA we're doomed! I must go on an orgy of chaining people up, and whipping them into submission in order to get them to loot the nearest computer warehouse!

Re:Inertia & Momentum - Star Stampede

[Nyh]

Since we didn't actually see where this star was coming from, the star could have been holding still for a long time while the galaxy far,far away came stampeding past like the wildebeast stampede in Lion King. To us stuck here on earth it would look exactly the same either way. So its not so much tht the star is being ejected, but that it survived the stampede.

Nice theory but incorrect. If you read TFA: "Less than 80 million years were needed for the star to reach its current location, which is consistent with its estimated age.".

If it only was sitting in space waiting for the galaxy to stampede by its age would be much, much higher.

Nyh