This
Astrobin Debut Object is a galaxy group of 5 galaxies, called Hickson 4, located in the constellation of Cetus at a declination of -21 degrees.
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.Like many of the Hickson galaxies, this is not a true cluster - the 5 galaxies are all at different distances and are only aligned through superposition from our apparent view. Most of the galaxies are about 0.3 to 0.4 billion light years away, although the dimmest one (4e) is almost 1 billion light years away.
The brightest galaxy in the group, always labelled “a” in Hickson groups, is also the largest. This galaxy is a pretty grand spiral and is a Milky Way size galaxy at about 110,000 light years in diameter.
There is a 6th distant galaxy in the group, just below and left of 4c, that Hickson missed. Perhaps it was mistaken for a star, or deemed as too small to include in the group (although other Hickson objects include galaxies this small).
Comments