A Galaxy Collision in Action

July 9, 2009
Credits: X-ray: NASA/CXC/CfA/E. O'Sullivan Optical: Canada-France-Hawaii-Telescope/Coelum

This beautiful image gives a new look at Stephan's Quintet, a compact group of galaxies discovered about 130 years ago and located about 280 million light years from Earth. The curved, light blue ridge running down the center of the image shows X-ray data from the Chandra X-ray Observatory.

Four of the galaxies in the group are visible in the optical image (yellow, red, white and blue) from the Canada-France- Hawaii Telescope. A labeled version identifies these galaxies (NGC 7317, NGC 7318a, NGC 7318b and NGC 7319) as well as a prominent foreground galaxy (NGC 7320) that is not a member of the group. The galaxy NGC 7318b is passing through the core of galaxies at almost 2 million miles per hour, and is thought to be causing the ridge of X- ray emission by generating a shock wave that heats the gas.

Additional heating by supernova explosions and stellar winds has also probably taken place in Stephan's Quintet. A larger halo of X-ray emission -- not shown here -- detected by ESA's XMM-Newton could be evidence of shock-heating by previous collisions between galaxies in this group. Some of the X-ray emission is likely also caused by binary systems containing that are losing material to or .

Stephan's Quintet provides a rare opportunity to observe a galaxy group in the process of evolving from an X-ray faint system dominated by spiral galaxies to a more developed system dominated by elliptical galaxies and bright X-ray emission. Being able to witness the dramatic effect of collisions in causing this evolution is important for increasing our understanding of the origins of the hot, X-ray bright halos of gas in groups of galaxies.

Stephan's Quintet shows an additional sign of complex interactions in the past, notably the long tails visible in the optical image. These features were probably caused by one or more passages through the galaxy group by NGC 7317.

Provided by JPL/NASA (news : web)

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3 / 5 (5) Jul 09, 2009
If you should ever get feeling bad about how things are going here on Earth, just be glad that our leading story isn't an incoming galaxy. "Twin star, ten-o-clock. DUCK!" Or maybe we could devise a way to generate electricity from incoming planets striking the Earth. 'Hate to let all that kinetic energy go to waste! I bet one planet could keep everything lit for a good 1,000 years if only a proper storage mechanism could be devised -- possibly spinning off a chunck of the planet into a new moon, and the energy could then be harnessed in the form of tides. Wait! we can already do that! Maybe we're the product of some collission and collapsed civilization of millions years ago, and that is where our moon came from! 'Ever think about that? "Heads up! Black Hole at 6-30. That sucks! There goes our moon. No, wait, that was a moon from Saturn. Hang on to your seats, we're next." "Next up, Michael Jackson's mother is still mad at contending party for control son's estate."
5 / 5 (1) Jul 16, 2009
I find the bright blue arc of young, blue star clusters and hot, x-ray emitting just to the north of NGC 7320 (bottom center) to be most amazing. This region of Stephan's Quintet has been extensively studied from the sub-mm to x-ray region of the spectrum.

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