Giovanni Carraro et al. 2007 The Astronomical Journal 133 1058 doi:10.1086/510331
Giovanni Carraro1,5,6, André Moitinho2,7, Manuela Zoccali3, Ruben A. Vázquez4 and Gustavo Baume4
Show affiliationsWe perform a detailed photometric study of the stellar populations in a Galactic field at l = 232°, b = -6° in the Canis Major (CMa) constellation. We present the first U, B, V, I photometry of the old open cluster Auner 1 and determine it to be ≈3.25 Gyr old and to lie 8.9 kpc from the Sun. In the background of the cluster, at more than 9 kpc, we detect a young population most likely associated with the Norma-Cygnus spiral arm. Furthermore, we detect the signature of an older population and identify its turnoff and red giant branch. This population is found to have a mean age of 7 Gyr and a mean metallicity of Z = 0.006. We reconstruct the geometry of the stellar distribution and argue that this older population, often associated with the CMa "galaxy," in fact belongs to the warped old thin- and thick-disk components along this line of sight.
Galaxy: general; Hertzsprung-Russell diagram; open clusters and associations: general; open clusters and associations: individual (Auner 1)
Issue 3 (2007 March)
Received 2006 April 28, accepted for publication 2006 October 19
Published 2007 February 7
Giovanni Carraro et al. 2007 The Astronomical Journal 133 1058
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