NGC 6934

NGC 6934
NGC 6934 by Hubble Space Telescope; 3.5′ view
Observation data (J2000 epoch)
ClassVIII[1]
ConstellationDelphinus
Right ascension20h 34m 11.37s[2]
Declination+07° 24′ 16.1″[2]
Distance52 kly (16 kpc)[3]
Apparent magnitude (V)8.83[4]
Apparent dimensions (V)1.20′[5]
Physical characteristics
Absolute magnitude−7.65[6]
Mass2.95×105[7] M☉
Metallicity = –1.47[7] dex
Other designationsCaldwell 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 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]

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]

  1. ^ a b Cite error: The named reference hcob849_11 was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference Goldsbury2010 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference apj670_1_363 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference seds was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Forbes2008 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Dinescu2001 was invoked but never defined (see the help page).
  7. ^ a b c Cite error: The named reference apj742_1_51 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference simbad was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference Marino2018 was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference Kaluzny2001 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Wilhelm2002 was invoked but never defined (see the help page).