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NGC 6934

Globular cluster in the constellation Delphinus

NGC 6934
NGC 6934 by Hubble Space Telescope; 3.5′ view
Observation data (J2000 epoch)
Class	VIII[1]
Constellation	Delphinus
Right ascension	20h34m 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	${\displaystyle {\begin{smallmatrix}\left[{\ce {Fe}}/{\ce {H}}\right]\end{smallmatrix}}}$ = –1.47[7] dex
Other designations	Caldwell 47, NGC 6934[8]
See also: Globular cluster, List of globular clusters

NGC 6934 (also known as Caldwell 47) is a globular cluster of stars in the northern constellationofDelphinus, 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]

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 radiusof15″^[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]

• Media related to NGC 6934 at Wikimedia Commons
• NGC 6934 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
• A Distant Backwater of the Milky Way — ESA/Hubble Picture of the Week