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New Class of "Hypervelocity Stars" Discovered Escaping the Galaxy
Science_afficionado writes "Astronomers have discovered a surprising new class of 'hypervelocity stars' that are moving at more than a million miles per hour, fast enough to escape the gravitational grasp of the Milky Way galaxy. The 20 hyper stars are about the same size as the sun and, other than their extreme speed, have the same composition as the stars in the galactic disk. The big surprise is that they don't seem to come from the galaxy's center. The generally accepted mechanism for producing hypervelocity stars relies on the extreme gravitational field of the supermassive black hole that resides in the galaxy's core."
Maybe they're motherships :D
Heavens Gate was right all along! We missed the Mothership, guys!
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This is obviously 'Wan-to' up to his old tricks again.
They've spotted the explosion! Get in your General Products Hull and run for it! Our only salvation will be to find the Ringworld and move it out of the galaxy!
Assuming the observation gets studied and confirmed, this is probably far more common than one might initially expect.
The Milky Way has been on the move billions of years and occasionally meets up with star clusters or even dwarf galaxies.
Many of them probably settle in gravitationally, but some of them aren't going to and continue, largely, about their merry way if the relative speeds are right.
These stars could have been "acquired" 400 million years ago and it can take a long time to traverse a cross-segment of the Milky Way. And these stars would have to be smaller like our sun to have the right lifespan, and we wouldn't notice the really small ones (red dwarfs and such) because they would be hard to see so there is also a mix of observational factors in the equation.
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Maybe two super-massive black holes passed close to each other and spun these off?
Looking at the trajectories, wouldn't it be a possibility that these stars didn't originate in our galaxy, but rather, could have been tourists flung out in a similar fashion from another supermassive black hole outside of our own galaxy? Just passing through on various trajectories, from potentially various other galaxies. Not much thought put into this - maybe the distance from the nearest supermassive black hole outside of our own galaxy makes this an impossibility, but seems the article doesn't go into any theories at all.
They're just trying to see what they can get away with with a Newtonian approximation of gravity.
Aren't all objects' movement (speed) based on another objects movement (speed)? I mean, how fast is the Milky Way moving, and in what direction? And could that star just be sitting idle-ish, and our galaxy zipping past it? Are these question answerable?
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I never believed in it, anyway.
You probably don't believe in Monk, Night Court, or All In the Family either.
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space is not limited by the speed of light. What is the matter with you people?
Nothing is limited by the speed of light. The galactic constant is a phenomenon, not a limiting force.
the radio waves with Fox News started reaching them.
those aren't stars escaping the galaxy... those are golf balls being hit by people that watched those 8 free HD golf lesson videos to learn that weird golf trick to add an extra 20 yards.
Puppeteer planets escaping.
"If any question why we died, Tell them because our fathers lied."
From the ratio of stars being ejected, get the average rate of galaxy evaporation. Calculate backward to compute original mass of the milky way.
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These stars were ejected by the polar vortex.
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Maybe those starts just didn't like the neighbourhood they were in and decided to move house
TFA only says that the stars are travelling at a speed high enough that they can escape the pull of the galaxy, but doesn't give any explanation of WHAT is pushing or pulling the stars.
From TFA:
"The generally accepted mechanism for producing hypervelocity stars relies on the extreme gravitational field of the supermassive black hole that resides in the galaxy's core"
If it's the "supermassive black hole in the Galaxy core" that's doing the pulling, the stars should have travelling towards the core.
But they are travelling instead away from the core !
Instead of a "pull", it is as if there's something that's "PUSHING" them instead, and I do not think it's the supermassive blackhole (whose expertise is on the pulling part).
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I'd think an N-body problem with 300 billion stars would almost inevitably produce a few stars that just by chance get a sufficient number of gravitational slingshots from other stars that they get up to escape velocity...
Nah, I'm not speculating on where they got their energy at all.
Just pointing out that "million miles per hour" is not unusual in this universe, and therefore escape velocity is not that hard to achieve.
All it would take is galaxies spinning at different angles passing each other to spit off a few stars from the fringe edge. In fact the edge is probably ragged precisely because stars are occasionally spun off, like the outside skater roller derby.
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It's evidence Chuck Norris roundhouse kicked them out of HIS galaxy.
Those are spaceships!
Somebody stop them!
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What would happen if one of these beasts passed near the Solar system. For "near" consider the following scenarios: 1. Oort cloud. 2. Kuiper belt (I don't recall which one is closer and I'm too lazy to google it). 3. Just outside the orbit of Neptune. 4. Collision with Jupiter. 5. A passage inside the orbit of Mercury, no planetary collision or collision with Sol.
Finally, assuming none of these scenarios killed us by disruption the relationship between the Earth and Sun or flinging large bodies at us, how practical would it be to use a gravitational slingshot to launch a probe at high velocities?
For all intensive purposes, "whom" is no longer a word. That begs the question, "who cares"?
One of the theories for the origin of these hypervelocity stars is 3-body chaotic gravity assist. When two bodies are entering a gravity assist trajectory around a third, very massive body, their interactions sometimes add up in such a way that one body falls into a tight orbit, and another is ejected at a hypervelocity. Given the number of ternary star systems in the galaxy, this looks like a plausible explanation.
There is even a paper suggesting we could build an interstellar starship from two asteroids (PDF, 10 pages) using this mechanism. It was written by Josef L Breeden and presented at the 100 Year Starship conference.
Maybe the "UFOs" we've been seeing for the last couple of centuries are scout craft for these star systems, making sure there's no civilizations along their path that could cause trouble.
WARNING: I cannot be help responsible for the above, as apparently my cats have learned how to type.
All it would take is galaxies spinning at different angles passing each other to spit off a few stars from the fringe edge.
Isn't it known whether galaxies are close enough for that to be a factor? TFA doesn't say "and it's right next to the closest galaxy, so that's probably the reason." Furthermore, galaxies are mostly empty space, so it seems like how individual stars would interact to spin each other out would still be an interesting observation problem.
Why should their gender be relevant?
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In general, far as I can tell, galaxies don't really 'pass' each other. Big ones gobble up small ones as the Milky Way has undoubtedly done to many dwarf galaxies in the area. Big ones merge with other big ones, as we shall do with Andromeda in a couple of billion years. Those interactions will definitely send some stars hurtling through intergalactic space, but we won't have a disk galaxy after that. Sadly more of an amorphous blob.
I do not want your cheap brainburning drugs. They are useless for work. And I am a working man today.
His take on such matters is generally well informed and interesting.
I do not want your cheap brainburning drugs. They are useless for work. And I am a working man today.
I wonder how it would have felt for humanity if Earth happened to orbit such a star, and we knew that every moment we were going farther and farther from the galaxy.
In general, far as I can tell, galaxies don't really 'pass' each other. Big ones gobble up small ones as the Milky Way has undoubtedly done to many dwarf galaxies in the area. Big ones merge with other big ones, as we shall do with Andromeda in a couple of billion years. Those interactions will definitely send some stars hurtling through intergalactic space, but we won't have a disk galaxy after that. Sadly more of an amorphous blob.
I'm not prepared to argue that point, although I've seen some reference in passing to galaxies passing right through other galaxies.
But I'm not sure it matters, because any interaction between galaxies, might leave remnants of one traveling at odd angles
and speeds within the other. I write code for a living, and therefore, I'm totally guessing here.
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Oh, I also found some info about random non-galaxy stars that theoretically might be "picked up" by a galaxy.
http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question29.html
http://www.astronomycafe.net/qadir/q2486.html
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I have read quite a bit about science that interests me and one of the subjects was "the ultimate fate of the universe". One detail that stuck out was that all galaxies evaporate given enough time. Even with a small rate of evaporation (say, an average of 10 billion years for any given star), our galaxy has 300 billion stars, so you're bound to see a few flying away "naturally" at any point time.
If they really wanted to know how these particular stars got boosted without going through the galactic center, they'd take a look at one of the already-done-to-death simulations.
Hell, I betcha someone could scale down one of these simulations, post it as a crappy javascript app and say "hey look here's how it happens!", and not even need the chops to describe it analytically.
Oh no worries, I'm quite prepared to accept that it's something that happens - the Universe always seems to find an exception to any rule of thumb we can come up with..! And no doubt when interactions involve billions of stars there's always going to be an outlier group in which something different or strange is going on. My only point was that generally these interactions involve merging, simply as a consequence of gravity always being attractive. For the record I'm also not an expert in this (network eng). :)
I do not want your cheap brainburning drugs. They are useless for work. And I am a working man today.