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."

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.

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!!

[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...

Does anyone know...

[midifarm]

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

Peace

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 [hypertextbook.com], 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 [ucar.edu], were are traveling at approximately 67000mph.

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

Why aren't you torn apart?

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.

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.

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. [utoronto.ca]

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: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?

More info

[Woogiemonger]

I found more info on this, including more numbers, from this Reuters article [yahoo.com]. 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 [usatoday.com] moves at about 0.999c.

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: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:RFI

[GodLived]

It sounds like Frederik Pohl's The World at the End of Time [ffbooks.co.uk].

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.

-

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"

Re:To put that in perspective...

[Anonymous Coward]

your google calc link was boring

I would have done this :p

0.002 [google.com]

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: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 - 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 [amazon.com]. 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.

Re:Astronomy / Math question

[chinton]

Quoting a related space.com [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: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: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.

Or....

[fleener]

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

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?