Credit: X-ray (NASA/CXC/SAO/E.Nardini et al); Optical (NASA/STScI)
Galaxies go bump in the night. Often, one galaxy will cross paths with another, and these rather frequent cosmic collisions are important for driving the evolution of galaxies. Pictured above is a beautiful example of one such collsion, a merging pair of spiral galaxies called NGC 6240. Rarely do such galaxy mergers involve the direct collisions of individual stars, since stars are spread out too widely. But gravitational interactions encountered during these collisions violently stir up the stars, gas, dust and dark matter as the colliding galaxies merge into one. During such encounters, stars can get thrown out into the intergalactic void, central supermassive black holes can eventually merge, and bursts of new stars can form as interstellar gas clouds get smashed together. The image above of NGC 6240 combines a Hubble optical image and a Chandra X-ray image (shown in purple). The Chandra image shows that a huge, hot halo of gas containing about ten billion solar masses of gas surrounds NGC 6240. Careful analysis of the distribution of this hot gas and its chemical makeup suggest that it was formed by the birth and supernovae death of massive stars during a number of starburst events over a period of about 200 million years. It is not yet clear whether this hot gas will remain with NGC 6240 as the pair evolves further, or whether it will be lost to (and enrich) the dark space between galaxies.
Published: May 13, 2013
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Page Author: Dr. Michael F. Corcoran
Last modified Monday, 20-May-2013 06:37:39 EDT