This
Astrobin Debut Object is a galaxy group of 4 galaxies, called Hickson 36, located in the constellation of Cancer at a declination of +16 degrees. This is one of the few Hickson clusters where all of the galaxies in the cluster are spiral galaxies.
This is not a true cluster -the galaxies are at much different distances away and are only aligned through superposition from our apparent view.
The brightest galaxy, Hickson 36a, is also known as IC 528. It is a beautiful magnitude 13 double ring spiral galaxy located 180 million light years away. It spans 1.5 arc-minutes, which corresponds to a diameter of 80,000 light years. Looking closely, you will see that the 2 rings are not quite aligned, with the inner ring pointing a bit further to the right. Such an alignment is unusual in double ring galaxies.
Edge-on spiral galaxies 36b and 36d are both much further away, at 0.7 billion light years. Each galaxy is slightly smaller than our Milky Way, at about 100,000 light years each in diameter.
Galaxy 36c is the smallest galaxy, at 35,000 light years in diameter. It is in-between the above galaxies in distance, at 400 million light years away.
Two other galaxies are also seen in the diameter of the Hickson 36 group. The galaxy at 3 o’clock from 36a looks like a close dwarf galaxy, while the galaxy at 5 o’clock looks like a more distant galaxy, perhaps at 2 billion light years away or more. I could not find reliable distance information for either of these galaxies.
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The Hickson catalog is a collection of 100 galaxy groups, established by Paul Hickson in 1982. Hickson compact galaxy groups are tightly spaced and somewhat isolated 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.
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