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
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
复制标题
l = 232°、b = -6°处银河场的光度测量：古老的疏散星团Auner 1、诺玛-天鹅座旋臂和扭曲的银河厚盘的特征
DOI：
--
复制
发表时间：
2006
期刊：
影响因子：
--
通讯作者：
G. Baume
中科院分区：
文献类型：
--
作者：
G. Carraro;A. Moitinho;M. Zoccali;R. Vazquez;G. Baume
本文对大犬星座（CMa）中l = 232°，B = -6°的银河场中的恒星群体进行了详细的光度学研究。我们首次对老疏散星团Auner 1进行了U、B、V、I测光，确定它的年龄为3.25 Gyr，距离太阳8.9 kpc。在该星团的背景中，在超过9 kpc处，我们发现了一个年轻的种群，它很可能与诺玛-天鹅座旋臂有关。此外，我们还发现了一个老年种群的特征，并确定了它的分叉和红巨星分支。这个人口被发现有7 Gyr的平均年龄和Z = 0.006的平均金属丰度。我们重建的几何形状的恒星分布，并认为，这个较老的人口，往往与CMa“星系”，实际上属于扭曲的老薄和厚盘组件沿着这条视线。
We 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.