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Galaxies Colliding: Edge-On View
Chris Mihos (Case Western Reserve University)
Video: 1 MB, MPEG
Galaxies like the Milky Way often have a number of much smaller, satellite
galaxies orbiting around them like moths around a campfire. What happens if one of these satellite galaxies comes too close to its giant neighbor? This movie shows one possible outcome; the satellite falls to the center of the large galaxy, puffing it up in the process.
Galactic acquisition
In this simulation, we begin by looking at the two galaxies from the side. The blue ball on the right is a spherical satellite galaxy; the yellow object is a large spiral galaxy as seen from its side, or edge-on. Over the course of several hundred million years, the satellite goes above, then below the large galaxy's disk, then above again. Finally, the hapless satellite is pulled into the galactic bulge, becoming part of the now-larger galaxy.
Tracing a galactic collision
According to this supercomputer simulation, the collision tosses parts of both galaxies into a scattered halo around the disk and bulge. This result suggests that astronomers can look for such galactic crumbs
to see if one galaxy has recently consumed another. The latest theories of galaxy formation suggest that our own Milky Way Galaxy may have gobbled dozens, even hundreds, of small galaxies to attain the size and mass it has today.
Charles Liu
A Prograde-Retrograde Galaxy Collision
Chris Mihos (Case Western Reserve University)
Video: 620 kB, MPEG
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.
Tracing a galactic collision
According to this supercomputer simulation, the collision tosses parts of both galaxies into a scattered halo around the disk and bulge. This result suggests that astronomers can look for such galactic crumbs
to see if one galaxy has recently consumed another. The latest theories of galaxy formation suggest that our own Milky Way Galaxy may have gobbled dozens, even hundreds, of small galaxies to attain the size and mass it has today.
Charles Liu
Stellar Encounters
Joshua E. Barnes (University of Hawaii)
Video: 1 MB, MPEG
Close encounters between stars are very rare. Only a few of the billions of stars in a typical galaxy will ever collide. Nonetheless, encounters between stars can play an interesting role in the formation of exotic star systems. This supercomputer simulation shows what might happen if a small star crashes into a larger one.
When stars collide
The movie shows one star crashing into another star twice its mass. Stars are not solid objects, but are composed of gas that surrounds a small, dense core. When stars collide, their cores spiral into each other, while their gaseous envelopes swirl about. The friction caused by all this motion releases a tremendous amount of heat and energy. This is shown in the movie by the colors in the stars: red regions have high energy while blue regions have low energy.
Tracing a galactic collision
According to this supercomputer simulation, the collision tosses parts of both galaxies into a scattered halo around the disk and bulge. This result suggests that astronomers can look for such galactic crumbs
to see if one galaxy has recently consumed another. The latest theories of galaxy formation suggest that our own Milky Way Galaxy may have gobbled dozens, even hundreds, of small galaxies to attain the size and mass it has today.
Gordon Myers
