This is a galaxy group of 4 spiral galaxies, called Hickson 78, located in the constellation of Draco at a declination of +68 degrees. The 4 galaxies are all at different distances and are only aligned through superposition from our apparent view. The distances range from 400 million light years for Hickson 78a to almost 1 billion light years for Hickson 78c.
The largest and brightest galaxy, Hickson 78a, is also known as UGC 10057. It is a magnitude 14.4 barred galaxy with a graceful pseudoring. This pseudoring is of the rarer type R2', with the ring parallel to the bar. It spans almost 2 arc-minutes, which corresponds to a large diameter of 200,000 light years. My collection of R2' pseudorings is
here.
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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