Credit: Jim Fordice
Astronomical and Imaging Data
| RA: | 17h 05m 09.13s |
| DEC: | -22° 42′ 30.1″ |
| MAG: | 9.35 |
| Diameter: | 4.9′ |
| Const: | Oph |
| OTA | Planewave CDK24 |
| Focal Length | 3962mm |
| Camera | QHY 600M |
| Site | El Sauce Observatory,Río Hurtado, Chile |
| Sky Quality | Bortle 1 |
Useful Informations
NGC 6287 is a globular cluster located in the southern constellation of Ophiuchus. It is notable for its position relatively close to the Galactic Center and its extremely metal-poor nature, making it a key object for studying the early chemical evolution of the Milky Way.
Key Astrophysical Properties
- Location and Distance: NGC 6287 is considered an inner halo cluster. It lies approximately 30,600 light years (or 9.4 kiloparsecs) from the Sun. Critically, it is situated close to the central hub of the Galaxy, with a Galactocentric distance estimated to be as small as 1.57 kiloparsecs.
- Metallicity and Age: The cluster is highly metal-poor, one of the most chemically primitive star systems known, with a measured iron abundance [Fe/H] as low as -2.01 (approximately 1% of the Sun’s metal content). This low metallicity, combined with its well-defined blue horizontal branch population, confirms its extreme age, which is comparable to the oldest globular clusters like M92.
- Kinematics: The cluster exhibits a high heliocentric radial velocity of about -288.7 kilometers per second. The significant negative velocity indicates that it is rapidly approaching the Sun, a kinematic property often shared by objects on highly eccentric orbits within the inner halo.
Structure and Appearance
- Concentration: NGC 6287 is a relatively highly concentrated system, classified as Class VII on the Shapley–Sawyer concentration scale. This high density is consistent with its location near the Galactic plane, where tidal forces are stronger and tend to strip away the more loosely bound outer stars.
- Apparent Properties: The cluster has an integrated visual magnitude of approximately 9.3 and spans an apparent diameter of about 4.8 arc minutes.
- Surroundings: Due to its proximity to the disk, the cluster is viewed through substantial amounts of obscuring interstellar dust. It is known to lie in the direction of several irregular dark nebulae, specifically Barnard 47 and Barnard 51, which contribute to the high interstellar reddening observed in this line of sight.