Mayall II

Also known by the designations G1, SKHB 1, and HBK 0-1, Mayall II is a globular cluster of the Andromeda Galaxy.

It is located 170,000 light years from the Milky Way, and is the brightest absolute magnitude globular cluster in the Local Group. G1 is considered to have twice the mass of Omega Centauri.

Because of the widespread distribution of metallicity, indicating multiple star generations and a large stellar creation period, many contend that it is not a true globular cluster, but is actually the galactic core that remains of a dwarf galaxy consumed by Andromeda.