NGC 922: A ring galaxy about 157 million light years from Earth.
NGC 922 was formed by the collision between two galaxies – one seen in this composite image (where X-rays from Chandra are red and optical data from Hubble appear as pink, blue, and yellow) and another located outside the field of view. This collision triggered the formation of new stars in the shape of a ring. Some of these were massive stars that evolved and collapsed to form black holes. Astronomers are studying NGC 922 and other galaxies to determine the galactic composition that produces the biggest stellar-mass black holes.
Scale: Main image: 1.6 arcmin across (about 73,000 light years).
Image credit: X-ray (NASA/CXC/SAO/A.Prestwich et al); Optical (NASA/STScI)
Note: For more information, see NGC 922: Searching for the Best Black Hole Recipe.