arXiv 0905.30172009-05-19astro-ph.GA

9个银河星团场中的均匀光度学和恒星计数

Homogeneous photometry and star counts in the field of 9 Galactic star clusters

Anton Seleznev, Giovanni Carraro, Edgardo Costa, Alexhander Loktin

备注：: 37 pages, 16 eps figures, in press in New Astronomy
DOI：: 10.1016/j.newast.2009.05.011

摘要：

我们提出了均匀的$V,I$ CCD测光的九个恒星领域的两个内象限的银河平面。大部分这些场的观测线都指向银河系的最内部，那里的银河场非常密集，消光率很高，而且是不规则的。根据几个星表，我们的九个区域都集中在银河系的星团上，即Trumpler 13、Trumpler 20、Lynga 4、Hogg 19、Lynga 12、Trumpler 25、Trumpler 26、Ruprecht 128和Trumpler 34。除了它们的坐标，以及在某些情况下额外的基本数据（主要来自2 MASS档案），它们的属性知之甚少。通过恒星计数技术和场星净化色星等图，这些视觉超密度的性质和大小已经建立，并在可能的情况下，新的集群的基本参数已经推导出来。为了加强我们的研究结果，我们补充我们的数据集与JHK $_{s}$光度从2 MASS档案，我们分析使用适当定义的Q参数。大多数星系团都投射到船底座-人马座旋臂上，因此，我们在大多数其他领域的彩色星等图中发现了几个由旋臂内年轻人口产生的独特序列。我们的研究发现的最有趣的例子可能是特朗普勒20，它似乎比以前认为的要古老得多，正如它突出的双红色团块所表明的那样;霍格19，一个以前被忽视的古老疏散星团，它在银河系的这些区域的存在令人费解。

英文摘要：

We present homogeneous $V,I$ CCD photometry of nine stellar fields in the two inner quadrants of the Galactic plane. The lines-of-view to most of these fields aim in the direction of the very inner Galaxy, where the Galactic field is very dense, and extinction is high and patchy. Our nine fields are, according to several catalogs, centred on Galactic star clusters, namely Trumpler 13, Trumpler 20, Lynga 4, Hogg 19, Lynga 12, Trumpler 25, Trumpler 26, Ruprecht 128, and Trumpler 34. Apart from their coordinates, and in some cases additional basic data (mainly from the 2MASS archive), their properties are poorly known. By means of star count techniques and field star decontaminated Color-Magnitude diagrams, the nature and size of these visual over-densities has been established; and, when possible, new cluster fundamental parameters have been derived. To strengthen our findings, we complement our data-set with JHK$_{s}$ photometry from the 2MASS archive, that we analyze using a suitably defined Q-parameter. Most clusters are projected towards the Carina-Sagittarium spiral arm. Because of that, we detect in the Color Magnitude Diagrams of most of the other fields several distinctive sequences produced by young population within the arm. All the clusters are of intermediate or old age. The most interesting cases detected by our study are, perhaps, that of Trumpler 20, which seems to be much older than previously believed, as indicated by its prominent -and double- red clump; and that of Hogg 19, a previously overlooked old open cluster, whose existence in such regions of the Milky Way is puzzling.

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英文摘要：

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