Hickson Compact Group 7
HCG 7 is a small cluster of four large galaxies in the equatorial constellation Cetus. HCG stands for the Hickson Compact Group catalog which consists of 100 entries. The number seven is a group of galaxies, some tens of million light years away. It is interesting in terms of galactic evolution, due to the manifold of galactic stages of stellar and dust formation, it offers to observe: a spiral galaxy, an older "red spiral", a transitional prae merger and an elongated elliptical galaxy. NGC 197 shows some merger activity and had (probably) experienced a closer encounter with the elliptical galaxy NGC 198.
The IVU picture shows the four large members of HGC 7 in the (I) infrared, (V) visible light and (U) ultraviolet part of the spectrum. Ionized gas is represented in blue (far ultraviolet radiation). Bulges of stars are color-coded in red and orange (visible and IR radiation). Stars appear as red, yellow and green dots all over this frame.