This
Astrobin Debut Object is a galaxy group of 6 galaxies, called Hickson 20, located 0.7 billion light years away in the constellation of Aries at a declination of +26 degrees.
This is a true cluster -the 6 galaxies are all at approximately the same distance. I don’t see much disturbance, so they are not likely close enough to each other to be interacting.
Compared to the typical Hickson group, Hickson 20 is a bit further away (at 700 mly), slightly smaller in overall size (at 1.5 arc-minutes overall diameter), and slightly dimmer in brightness (at 13.0 group magnitude) than most.
The biggest and brightest galaxy of the group, Hickson 20a, is also known as LEDA 12477. It is a magnitude 14.5 galaxy which spans 30 arc-seconds. This corresponds to an actual diameter of 110,000 light years.
The nice edge-on spiral at the upper right is further away, almost 1 billion light years, and is the largest galaxy in the image at 150,000 light years in diameter.
The Hickson catalog is a collection of 100 galaxy groups, established by Paul Hickson in 1982. Hickson compact galaxy groups are strictly defined by 3 criteria: number of galaxies, total magnitude, and isolation from other galaxies. A typical Hickson group has 4 galaxies, but some have up to 8. You can see more about Hickson galaxy groups in my
Astrobin Hickson Collection.
My Hickson collection is now complete. Compilation posters coming tomorrow.
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