Chris Mihos (Case Western Reserve University)

When galaxies collide, a number of factors affect the outcome. This movie shows two large spiral galaxies colliding under a particular set of initial conditions: one galaxy is rotating clockwise, the other counterclockwise. The simulation follows the first 100 million years of the collision. The complexity of these calculations requires a powerful supercomputer and many hours (and sometimes days) to run.

Collisions create star formation

The blue material represents stars in these galaxies, while the yellow material represents clouds of hydrogen gas that could form new stars during the collision. Before the collision, both stars and gas are evenly distributed throughout each galaxy, but as the galaxies crash into each other, the stars spread out into a much larger volume. Conversely, the gas gathers into tight knots and thin threads. This behavior suggests that, because of the collision, new stars will form in massive, concentrated starbursts. The directions of the galaxies' spin affects how the stellar and gaseous matter move; different combinations of spins, collision speeds, and angles will produce markedly different results.

Charles Liu