| NGC 6791 | |
|---|---|
 Detail from the Kepler image showing NGC 6791. Celestial north is to the left.a | |
| Observation data (J2000 epoch) | |
| Right ascension | 19h 20m 53s[1] |
| Declination | +37° 46.3′[1] |
| Distance | ~13,300 ly (4078 pc) |
| Apparent magnitude (V) | +9.5[1] |
| Apparent dimensions (V) | 16'[2] |
| Physical characteristics | |
| One of the oldest known open clusters | |
| Other designations | C 1919+377, Cl Berkeley 46, OCl 142.0,[1] GC 4492[2] |
| Associations | |
| Constellation | Lyra |
NGC 6791 is an open star cluster in the Lyra constellation.[1] It was discovered by Friedrich August Theodor Winnecke in 1853. At roughly 8 billion years old, and with an iron to hydrogen abundance ratio that is more than twice that of the Sun, it is one of the oldest and most metal-rich clusters in the Milky Way. This is contrary to the typical rule-of-thumb where older means more metal-poor. Compounded with the fact that it has an unusually high population of stars, NGC 6791 is among the most studied clusters in the sky.[3][4]
- ^ a b c d e "NGC 6791". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2009-05-10.
- ^ a b NGC online. "NGC 6791". Archived from the original on 2007-08-19. Retrieved 2009-05-10.
- ^ Chaboyer; Green, Elizabeth M.; Liebert, James (March 1999). "The Age, Extinction, and Distance of the Old, Metal-rich Open Cluster NGC 6791" (PDF). The Astronomical Journal. 117 (3): 1360–1374. arXiv:astro-ph/9812097. Bibcode:1999AJ....117.1360C. doi:10.1086/300794. S2CID 16633286.
- ^ Kaluzny; Udalski, A. (1992). "Photometric Study of the Old Open Cluster NGC 6791" (PDF). Acta Astronomica. 42 (1): 29–47. Bibcode:1992AcA....42...29K.