From: Andy Soos, ENN
Published November 23, 2010 03:28 PM

Galactic Outburst

Astronomers using NASA's Spitzer Space Telescope have found a stunning burst of star formation that beams out as much infrared light as an entire galaxy. The collision of two spiral galaxies has triggered this explosion, which is cloaked by dust that renders its stars nearly invisible in other wavelengths of light. Although bright as this is, it pales in comparison to a quasar. The brightest known quasar is 3C 273 in the constellation of Virgo. This quasar's luminosity is about 2 trillion times that of our sun, or about 100 times that of the total light of average giant galaxies like our Milky Way. The starburst newly revealed by Spitzer stands as the most luminous ever seen taking place away from the centers, or nuclei, of merging parent galaxies. It blazes ten times brighter than the nearby Universe's previous most famous starburst that gleams in another galactic smashup known as the Antennae Galaxy.




Galaxy mergers are now known to be more common than was previously thought. They were even more common in the early universe than they are today. The early universe was smaller, so galaxies were closer together and therefore more prone to smash-ups. Even apparently isolated galaxies can show signs of past mergers in their internal structure.Our own Milky Way contains the debris of the many smaller galaxies it has brushed against and devoured in the past. And it has not stopped munching away at its neighbors: It is currently absorbing the Sagittarius dwarf elliptical galaxy.




Typically the first sign of a collision is a bridge of matter connecting two galaxies as gravity's first gentle tugs tease out dust and gas. As the outer reaches of the galaxies begin to interact, long streamers of gas and dust, called tidal tails, sweep back to wrap around the galactic cores.But giant, diffuse clouds of gas and dust in galaxies do crash together - passing through each other somewhat like ocean waves - and in turn spur the gravitational collapse of dense pockets of matter into new stars. These young, hot stars shine intensely in the energetic ultraviolet part of the spectrum.


For further information:  http://www.spitzer.caltech.edu/news/1224-feature10-19-Spitzer-Reveals-a-Buried-Explosion-Sparked-by-a-Galactic-Train-Wreck

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