| Mayall II | |
| Ra: | [1] |
| Appmag V: | +13.81 |
| Mass Kg: | 2 |
| Mass Msol: | 1[2] |
| Radius Ly: | 21.2 ± 1.0 ly (6.5 ± 0.3 pc) (Half light radius rh) and tidal radius 263.2 ± 12.7 ly (80.7 ± 3.9 pc)[3] |
| Age: | ~ 12 Gyr |
| Names: | SKHB 1, HBK 0-1 |
Mayall II, also known as NGC-224-G1, SKHB 1, GSC 2788:2139, HBK 0-1, M31GC J003247+393440 or Andromeda's Cluster, is a globular cluster orbiting M31, the Andromeda Galaxy.
It is located 130000ly[3] from the Andromeda Galaxy's galactic core, and is the brightest[3] (by absolute magnitude) globular cluster in the Local Group, with an absolute visual magnitude of -10.94 and the luminosity of 2 million Suns. It has an apparent magnitude of 13.81 in V band. Mayall II is considered to have twice the mass of Omega Centauri, and may contain a central, intermediate-mass (~ 2 M⊙) black hole.[3]
It was first identified as a possible globular cluster by American astronomers Nicholas Mayall and Olin J. Eggen in 1953 using a Palomar 48inches Schmidt plate exposed in 1948.[3]
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.[3] [4]