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

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: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?

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.

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: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: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.

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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.