Bigger Galaxy Eats Smaller Neighbor

Mr.Happy3050 writes "CNN is reporting here that the large galaxy Centarus A absorbed a smaller neighboring galaxy 200-400 million years ago. The absorption created a line of blue stars thousand of light-years across."

Comments

A question

[Syncdata]

I was of the understanding that, were two galaxies to cross through each other's paths, that it would be more or less clean, due to the sheer ammount of space in comparison to the matter in the galaxies.

Re:A question

[drudd]

It is true that none (or very few) of the stars which make up the two galaxies will collide. But the gas will collide (often leading to starformation, or the stripping of gas from galaxies).

Also, all components are interacting gravitationally, so the structure of the galaxies does not survive "cleanly." Instead there are very interesting features, tidal tails, spherical shells, and usually the major fractions of the two galaxies settle down into a single system very different from the two progenitors (assuming the two initial galaxies are roughly the same size).

Doug

Question

[photon317]

Now I can see a large galaxy colliding with a smaller cluster of dwarfs or whatever it was - but at the end of the article they talk as if it's a fairly well-known fact that the Milky Way and Andromeda will collide at some point in the distant future. Now, I seem to remember the classic marker-spots-on-a-balloon explanation that so long as the universe is expanding each galaxy continues to get further and further away from each at a high speed (near light speed but not quite?). Is this simplistic explanation wrong, and in fact large stable galaxies can and do collide into each other, or are they talking in terms of after a theoretical turning point where theuniverse starts shrinking again?

Re:Dust clouds

[Alsee]

The perfect gas law is a pretty poor approximation of interstellar gas. Gravity, magnetism and radiation pressure have substantial effects. The gasses is also generally not in equlibrium. Remember these are distances of thousands of light years, an effect like a nova can create disruptions and "winds" that last millions of years. A galactic collision would throw it far out of equilibrium for 100's of millions of years.

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