View Full Version : M31 Already Collided With Milky Way?

2004-Apr-29, 02:02 PM
There is an intersting paper in arXive today about the idea that the Milky Way and Andromeda [M31] have already collided one or more times, and that this has caused the creation of the LMC, SMC, and quite a few of the other nearby dwarf galaxies.

Paper on Creation of Local Dwarf Galaxies (http://www.arxiv.org/PS_cache/astro-ph/pdf/0404/0404547.pdf)

The paper goes through a number of views of the local group from different angles, and shows the calculated orbits of the members over the last 12 billion years. The paper does not offer proof that this happened, but points out that we will be able to make sufficiently accurate proper motion studies in the next decade to verify the motions they predict based on this theory.

2004-Apr-30, 04:58 AM
I'd be interested to know if the Sun is predicted to be thrown out of the galaxy as a result...

2004-Apr-30, 10:46 AM
Originally posted by DippyHippy@Apr 30 2004, 04:58 AM
I'd be interested to know if the Sun is predicted to be thrown out of the galaxy as a result...
That would be interesting to know. The paper didn't suggest anything like that. The paper dicussed a model for what might already have happened with little or no looking forward to the next encounter.

2004-Apr-30, 10:56 PM
Now I think about it, you'd have to have a precise location for our Sun and a pretty exact idea of the dimensions of the Milky Way to see the Sun's fate...

2004-May-02, 06:13 PM
One of the news services had an article on that - to the effect that our Milky Way and Andromeda had already crashed and seperated, they had a picture of the overlaping galaxies, and Sol System was smack dead in the middle of it.
Now with interstellar distances, a pass thru resulting in a collision is small, but how about this - two solar systems come close enough gravitaionally that they become one - or at least one pulls the loosely bound planets and moons from one and joins it to its own system.
Had something like this happened, we might end with some of the anomilies we see in our system today.
Or maybe Velikovsky had it right and Comet Venus, born of the Great Red Spot on Jupiter, finally came in close enough to be captured into a permenante orbit, and ejected Mars out of the orbit it formerly held, resulting in hte system we have today. (World's in Collision - I don't much like his other writings, but this was written in 37 or 48ish, before sputnik, and he's doing a pretty good job of predicting what we will find - gave his source as Mesopotamian astrology texts put down as myth due to the misinformation on Venus.)
Something to think about, anyway. :D

2004-May-02, 10:42 PM
That article gives the date of the collision between the Milky Way and Andromeda as 10 billion years ago. That's 5 and a half billion years before the solar system formed, so it probably didn't have much effect on us.

And it was 9,999,998,000 years before Velikovsky's hypothetical (and thoroughly debunked) game of cosmic pinball was supposed to happen, so it probably isn't related much to that either.