Palomar 12 | |
Epoch: | J2000 |
Class: | XII |
Constellation: | Capricornus |
Dist Ly: | 63.6+/- |
Appmag V: | 11.99 |
Size V: | 17.4 |
Radius Ly: | 162 ± 8 ly[1] |
Metal Fe: | –0.85 |
Age: | 6.5 Gyr |
Notes: | Probably extragalactic |
Names: | GCl 123 |
Palomar 12 is a globular cluster in the constellation Capricornus, and is a member of the Palomar Globular Clusters group.
First discovered on the National Geographic Society – Palomar Observatory Sky Survey plates by Robert George Harrington and Fritz Zwicky,[2] it was initially catalogued as a globular cluster; however, Zwicky came to believe it was actually a nearby dwarf galaxy in the Local Group. It is a relatively young cluster, being about 30% younger than most of the globular clusters in the Milky Way. It is metal-rich with a metallicity of . It has an average luminosity distribution of .[3]
Based on proper motion studies, this cluster was first suspected in 2000 to have been captured from the Sagittarius Dwarf Elliptical Galaxy (SagDEG) about 1.7 Ga ago.[4] It is now generally believed to have originated in that galaxy and is associated with the Sagittarius Stream. It is estimated to be 6.5 Gyr old.