Alpha Persei Cluster
| Alpha Persei Cluster | |
|---|---|
 | |
| Observation data (2000.0 epoch) | |
| Right ascension | 03h 26m 42.0s |
| Declination | +48° 48′ 00″ |
| Distance | 570 ly (175 pc) |
| Apparent magnitude (V) | 1.2 |
| Apparent dimensions (V) | 6.1° |
| Physical characteristics | |
| Estimated age | 49.5±6.0 Myr |
| Other designations | Per OB3, Cr 39, Mel 20, OCl 392.0 |
| Associations | |
| Constellation | Perseus |
The Alpha Persei Cluster, also known as Melotte 20 or Collinder 39, is an open cluster of stars in the northern constellation of Perseus. To the naked eye, the cluster consists of several blue-hued spectral type B stars. The most luminous member is the ~2nd magnitude yellow supergiant Mirfak, also known as Alpha Persei. Bright members also include Delta, Sigma, Psi, 29, 30, 34, and 48 Persei. The Hipparcos satellite and infrared color-magnitude diagram fitting have been used to establish a distance to the cluster of ~560 light-years (172 pc). The distance established via the independent analyses agree, thereby making the cluster an important rung on the cosmic distance ladder. As seen from the Earth, the extinction of the cluster due to interstellar dust is around 0.30 magnitudes.