Terzan 7

Terzan 7
Terzan7 by Hubble Space Telescope; 3.5′ view
Observation data (J2000 epoch)
ConstellationSagittarius
Right ascension19h 17m 43.92s[1]
Declination−34° 39′ 27.8″[1]
Distance75.7 kly (23.2 kpc)[2]
Apparent magnitude (V)12.0[2]
Apparent dimensions (V)7.3′[2]
Physical characteristics
Radius160 ly[a]
VHB17.76[3]
Estimated age7.5 Gyr[4]
Notable featuresyoung extragalactic globular
Other designationsTer 7,[4] GCl 109.1[5]
See also: Globular cluster, List of globular clusters

Terzan 7 is a sparse and young globular cluster that is believed to have originated in the Sagittarius Dwarf Spheroidal Galaxy (Sag DEG) and is physically associated with it. It is relatively metal rich with [Fe/H] = -0.6[6] and an estimated age of 7.5 Gyr.[4] Terzan 7 has low levels of nickel ([Ni/Fe] = -0.2) which supports its membership in the Sag DEG system since it has a similar chemical signature.[7] It has a rich population of blue stragglers that are strongly concentrated toward the center of Terzan 7.[8] It has an average luminosity distribution of Mv = -5.05.[9] It has a half-light radius (Rh) of 6.5pc.[10]

  1. ^ a b Cite error: The named reference aj140_6_1830 was invoked but never defined (see the help page).
  2. ^ a b c Terzan 7 @ seds, archived from the original on 2002-10-24
  3. ^ Wilson, Barbara (July 2, 1995), Obscure Globulars
  4. ^ a b c Geisler, Doug; Wallerstein, George; Smith, Verne V.; Casetti-Dinescu, Dana I. (September 2007), "Chemical Abundances and Kinematics in Globular Clusters and Local Group Dwarf Galaxies and Their Implications for Formation Theories of the Galactic Halo", The Publications of the Astronomical Society of the Pacific, 119 (859): 939–961, arXiv:0708.0570, Bibcode:2007PASP..119..939G, doi:10.1086/521990, S2CID 119599242
  5. ^ Cite error: The named reference simbad was invoked but never defined (see the help page).
  6. ^ Sbordone, L.; Bonifacio, P.; Marconi, G.; Buonanno, R.; Zaggia, S. (July 3, 2005), "Family ties: Abundances in Terzan 7, a Sgr dSph globular cluster", Astronomy and Astrophysics, 437 (3): 905–910, arXiv:astro-ph/0505307, Bibcode:2005A&A...437..905S, doi:10.1051/0004-6361:20042315, S2CID 11063189
  7. ^ Sbordone, L.; Bonifacio, P.; Marconi, G.; Buonanno, R. (2004), "Chemical abundances in Terzan 7", Memorie della Societa Astronomica Italiana, 75: 396, Bibcode:2004MmSAI..75..396S
  8. ^ Held, Enrico V.; Rosenberg, Alfred; Saviane, Ivo; Momany, Yazan (March 12–16, 2001), written at Pucon, Chile, Geisler, D.; Grebel, E.K.; Minniti, D. (eds.), "The Globular Cluster Terzan 7 in the Sagittarius Dwarf Spheroidal Galaxy", Extragalactic Star Clusters, 207, San Francisco: Astronomical Society of the Pacific (published 2002): 165, Bibcode:2002IAUS..207..165H
  9. ^ van den Bergh, Sidney (July 2007), "The Luminosity Distribution of Globular Clusters in Dwarf Galaxies", The Astronomical Journal, 134 (1): 344–345, arXiv:0704.2226, Bibcode:2007AJ....134..344V, doi:10.1086/518868, S2CID 14209616
  10. ^ van den Bergh, Sidney (February 2000), "Young Globular Clusters and Dwarf Spheroidals" (PDF), The Astrophysical Journal, 530 (2): 777–782, arXiv:astro-ph/9910243, Bibcode:2000ApJ...530..777V, doi:10.1086/308413, S2CID 14218931