IALP   13078
INSTITUTO DE ASTROFISICA LA PLATA
Unidad Ejecutora - UE
artículos
Título:
PHOTOMETRY OF A GALACTIC FIELD AT l = 232, b = - 6: THE OLD OPEN CLUSTER AUNER 1, THE NORMA-CYGNUS SPIRAL ARM, AND THE SIGNATURE OF THE WARPED GALACTIC THICK DISK
Autor/es:
GIOVANNI CARRARO; ANDRÉ MOITINHO; MANUELA ZOCCALI; RUBEN A. VÁZQUEZ; GUSTAVO BAUME
Revista:
ASTRONOMICAL JOURNAL
Referencias:
Año: 2007 vol. 133 p. 1058 - 1066
ISSN:
0004-6256
Resumen:
We perform a detailed photometric study of the stellar populations in a Galactic field at lº =232, bº = - 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 thickdisk components along this line of sight.