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Cosmic Fender Bender
A pileup of galactic proportions is captured in this Hubble Space Telescope image. The wreckage is visible, from the distorted shapes of the galaxies to the trails of debris streaming away from the accident scene.
This is Stephan’s Quintet, also known as Hickson Compact Group 92. Okay, first things first: it’s not really a quintet. The galaxy on the upper left, NGC 7320, is actually a foreground galaxy located about 40 million light-years from Earth. The remaining four galaxies are over seven times farther away, at an estimated distance of 300 million light-years in the constellation Pegasus. This was the first compact group of galaxies discovered, seen by Edouard M. Stephan in 1877.
But wait, aren’t there only four galaxies in this image? Look closely at the one closest to the image center. It looks like it has two cores, but it is really two separate galaxies, NGC 7318A and NGC 7318B. Their interaction has caused a lot of turmoil, shown by clusters of bright, young, blue stars and glowing pink clouds of hydrogen gas. Some of the new stars here are less than 10 million years old and are still nestled in their stellar nurseries.
Above and to the right is NGC 7319, a barred spiral with arms that swirl almost all the way back to the bar at their far ends. This galaxy too shows signs of interaction, with new stars forming in swaths of blue and entire star clusters blooming in pockets of red. There is even a trail of new stars seen streaming off to the upper left, forming in the galaxy’s wake of disturbed gas.
At the bottom of the image is the elliptical galaxy NGC 7317, appearing much less affected by what is going on around it. It’s like the pedestrian on the street corner, staring at the accident in the intersection.
Taken in visible and near-infrared light, the Hubble image traces stellar formation over hundreds of millions of years in these galaxies. Mature yellow and red stars abound near the galactic centers, while at the outskirts, new stars burst forth in blue from the carnage.
-JF
Image credit: NASA, ESA and the Hubble SM4 ERO Team
(via The Universe FB page)
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