Willman 1
| Willman 1 | |
|---|---|
| Observation data (J2000 epoch) | |
| Constellation | Ursa Major |
| Right ascension | 10h 49m 22.5s |
| Declination | +51° 03′ 00.4″ |
| Heliocentric radial velocity | -13.0 ± 1.1 km/s |
| Distance | 126 ± 2 kly (38.55 ± 0.45 kpc) |
| Apparent magnitude (V) | 15.4 ± 0.7 mag |
| Absolute magnitude (V) | -2.56 ± 0.74 mag |
| Characteristics | |
| Type | ultra-faint dwarf galaxy |
| Mass | 5.9+3.7 −3.4×105 M☉ |
| Mass/Light ratio | 660 ± 590 M☉/L☉ |
| Half-light radius (physical) | 26.8 ± 3.2 pc |
| Half-light radius (apparent) | 2.51 ± 0.22 arcmin |
| Other designations | |
| SDSS J1049+5103 | |
Willman 1 is an ultra faint dwarf galaxy discovered in 2005. It is named after Beth Willman of Haverford College who first identified it as an over-density of stars in the Sloan Digital Sky Survey (SDSS). The object is a satellite galaxy of the Milky Way and is located approximately 39 kiloparsecs (130,000 light-years) from Earth. Besides the Magellanic Clouds, it is the only other Milky Way dwarf galaxy named after a person and the only Milky Way dwarf galaxy named after a woman. Willman 1 was the lowest luminosity galaxy known at the time of discovery with an absolute magnitude of -2.5.