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New Class of "Hypervelocity Stars" Discovered Escaping the Galaxy 150

Posted by samzenpus
from the greased-lightning dept.
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."
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New Class of "Hypervelocity Stars" Discovered Escaping the Galaxy

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  • Assuming ... (Score:5, Interesting)

    by TrollstonButterbeans (2914995) on Thursday January 09, 2014 @09:37PM (#45913141)
    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.
  • by Rick in China (2934527) on Thursday January 09, 2014 @09:51PM (#45913259)
    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.
  • by BringsApples (3418089) on Thursday January 09, 2014 @09:57PM (#45913311)
    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?
  • by camperdave (969942) on Thursday January 09, 2014 @11:02PM (#45913669) Journal

    You're missing the point. These are stars moving at at abnormal speeds and can't be explained by any phenomenon we have observed before.

    Every gravity simulation I've ever run has had a few objects flung off at high speed. It doesn't take a lot.

  • interesting (Score:0, Interesting)

    by Anonymous Coward on Thursday January 09, 2014 @11:11PM (#45913703)

    So, what you are saying is that these so-called 'Hypervelocity' stars are actually no different from others stars in our galaxy, just that somehow their velocity has been given a new direction, like a rubber ball bouncing off a wall.

    The significance of this is that no new accelerating energy source is required in theory, since the 'rogue' stars already had the same mount of momentum energy as their 'normal' neighbours. Of course, we don't know what phenomenon would 'bounce' these stars into a new direction. It would be reasonable to think we may be seeing the result of some 'intelligent' action- a star-system scale project of engineering.

    It would be of interest to consider the objects in the future path of such stars. Were these mere random natural events, one would expect that the contents of space in front of these stars would be completely random. However, if the forward paths show content that cannot be described as random, this increases the likelihood that these stars were given their new direction on purpose.

     

  • by Vitriol+Angst (458300) on Friday January 10, 2014 @10:16AM (#45915943)

    They are likely wandering stars from another galaxy. Wasn't it estimated that we already had one galaxy pass through the Milky Way and sometime in the future we may pass through Andromeda?

    So perhaps there are three mechanisms for high speed stars;
    1) ejected by a super massive black hole.
    2) remnant of non-colliding stars from Galactic collisions (and actually, most stars don't hit each other in these situations).
    3) L3 advanced civilization finding that solar tourism is more fun if you can take all your stuff with you.

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