NGC 6934
Globular cluster in the constellation Delphinus
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NGC 6934 (also known as Caldwell 47) is a globular cluster of stars in the northern constellation of Delphinus, about 52 kilolight-years distant from the Sun.[3] It was discovered by the German-born astronomer William Herschel on 24 September 1785.[4] The cluster is following a highly eccentric orbit (with an eccentricity of 0.81) through the Milky Way along an orbital plane that is inclined by 73° to the galactic plane. It may share a common dynamic origin with NGC 5466.[6] As of 2018, it has been poorly studied.[9]
| NGC 6934 | |
|---|---|
NGC 6934 by Hubble Space Telescope; 3.5′ view | |
| Observation data (J2000 epoch) | |
| Class | VIII[1] |
| Constellation | Delphinus |
| Right ascension | 20h 34m 11.37s[2] |
| Declination | +07° 24′ 16.1″[2] |
| Distance | 52 kly (16 kpc)[3] |
| Apparent magnitude (V) | 8.83[4] |
| Apparent dimensions (V) | 1.20′[5] |
| Physical characteristics | |
| Absolute magnitude | −7.65[6] |
| Mass | 2.95×105[7] M☉ |
| Metallicity | [Fe/H] = –1.47[7] dex |
| Other designations | Caldwell 47, NGC 6934[8] |
This appears to be a Oosterhoff type I cluster with an intermediate metallicity.[10] It has an Shapley–Sawyer Concentration Class of VIII,[1] with a core radius of 15″[3] and a half-light radius of 36″.[5] The estimated mass is 295,000 times the mass of the Sun.[7] The cluster displays photometric anomalies, with a split subgiant branch on the HR diagram.[9] Searches for variable stars have discovered 85 in the cluster field, of which 79 are of the RR Lyrae class and one is a SX Phe variable.[10] There is some evidence for a tidal tail.[11]
