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Milky Way Galactic encounter?

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  1. May 17, 2012 #1
    I'm wondering if there is any evidence that our own Galaxy 'crashed' with other Galaxies in the past (e.g. with the Andormeda Galaxy?). Is there any evidence for this? Googled... but couldn't find much. If so can someone point me at some research on this?
     
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  3. May 17, 2012 #2

    HallsofIvy

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    My understanding is that the Andromeda galaxy is moving toward our galaxy and will pass through it some time (millions of years- I wouldn't worry about it!) in the future so has NOT passed through it in the past.

    I also seem to recall (people with better knowledge can correct this) that the distance between stars in both galaxies is so great that there would be relatively little disturbance in either galaxy.
     
  4. May 17, 2012 #3

    Millions?? I hope you mean billions, since 'millions' would be just 'tomorrow' in evolutionary time. Sure, stars do not collide in such a 'collision-less' encounter, but I'm not at all sure that it would have no dynamical effects. Just look at the pictures of other colliding galaxies.
     
  5. May 17, 2012 #4
    A collision between two galaxies would not be like a collision in a normal sense as most of the disruption would be caused not be physical collisions between stars and stuff but by the gravitational mayhem as the galaxies gravitational fields move through each other.
     
  6. May 17, 2012 #5
    Yes, we have evidence that several dwarf galaxies have merged (or are in the process of merging) with our galaxy. See, for example, the Sagittarius dwarf galaxy.
     
  7. May 17, 2012 #6

    phinds

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    Right, STARS don't, but galaxies do. Very few stars in either galaxy will have actual collisions, although some solar systems will be perturbed.

    EDIT: hm ... I think I may have misunderstood your post. Perhaps you were already saying that stars don't?
     
  8. May 17, 2012 #7
    Yes, star's don't collide. But I think that nevertheless a galactic encounter could have devastating effects on life. For example the tidal perturbation would probably trigger huge comet 'showers' from the Oort cloud.
     
  9. May 17, 2012 #8

    phinds

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    Yeah, sure could be. It IS surprizing though how empty galaxies are.
     
  10. May 17, 2012 #9
    From http://en.wikipedia.org/wiki/Andromeda–Milky_Way_collision
     
  11. May 17, 2012 #10
    Right now I think that there is a dwarf galaxy called the Sagittarius Dwarf Galaxy that is colliding with the Milky Way. I think that some theories for the formation of spiral galaxies consist of older galaxies merging together and forming the central bulge, which is full of older stars, and then the violence of that interaction causes the spiral arms to form.
     
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