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The Question
(Submitted February 13, 1998)
What exactly happens when two galaxies collide?
The Answer
Collisions of galaxies are tremendous things (a galaxy is a LOT
bigger than anything on Earth that you can imagine colliding!) and
generate a lot of energy, heating and mixing up the gases in the two
galaxies, making a good place for star formation. Unlike car collisions,
galaxies collisions take a very long time - as many as a billion years
or more for large galaxies!
There is lots of interesting information to be found on the web about what
happens when galaxies collide, and even some recent images of galaxies
that are in the process of colliding. A good brief explanation and images
can be found at:
http://astrowww.phys.uvic.ca/~patton/openhouse/collisions.html (http://astrowww.phys.uvic.ca/%7Epatton/openhouse/collisions.html)
Galaxy collisions are complex interactions and there are many people
trying to figure out how galaxies interact when they get close enough
together, and how they affect each other. One of the ways scientists do
this is by studying numerical simulations of colliding galaxies. The
simulations capture much of the important physics but can be run on a much
faster timescale. An example of this research can be found at:
http://www.sdsc.edu/IOTW/week47/iotw.html
There are also movies of computer simulations at the University of
Victoria site (the first one above).
Also:
http://www-astronomy.mps.ohio-state.edu/~ryden/ast162_7/notes30.html (http://www-astronomy.mps.ohio-state.edu/%7Eryden/ast162_7/notes30.html)
Allie Cliffe and Jim Lochner
for Ask a High-Energy Astronomer
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