标题： 银河低纬度区域的低吸收盘区 显示英文标题

标题： A low-absorption disk zone at low Galactic latitude in Centaurus

摘要： 我们研究了半人马座低吸收盘区内的两个恒星聚集点，它们分别位于$\ell=306.47^{\circ}$、$b=-0.61 ^{\circ}$和$\ell=307.01^{\circ}$、$b=-0.74 ^{\circ}$。 当前的分析主要基于 2MASS 光度测量以及光学光度测量。 根据颜色-亮度图和恒星径向密度剖面，我们表明这些聚集点并非疏散星团。 相反，它们似乎是通过一个不同reddening窗口看到的场星。 我们估计这两个恒星聚集点中的大部分恒星距离太阳大约$\sim1.5$千秒差距，这一距离与该方向上射手-船帆臂的距离一致。 这个低吸收窗口允许探测到盘区中除射手-船帆臂之外的遥远部分，可能是天鹰-牧夫臂的切线部分和/或该方向射手-船帆臂的远侧。 与射手-船帆臂相关的主序星被reddening$\ebv\sim0.5$，因此这个穿过盘区的窗口在reddening方面与 Bulge 的 Baade 窗口相当。 我们还研究了疏散星团候选体 Ru 166 的性质。 目前可用的数据还不足以确定 Ru 166 是一个实际的疏散星团还是通过小尺度低吸收窗口看到的场星。 显示英文摘要

摘要： We investigate the properties of two stellar concentrations in a low-absorption disk zone in Centaurus, located respectively at $\ell=306.47^{\circ}$, $b=-0.61 ^{\circ}$, and $\ell=307.01^{\circ}$, $b=-0.74 ^{\circ}$. The present analysis is based mostly on 2MASS photometry, as well as optical photometry. Based on colour-magnitude diagrams and stellar radial density profiles, we show that these concentrations are not open star clusters. Instead, they appear to be field stars seen through a differentially-reddened window. We estimate that the bulk of the stars in both stellar concentrations is located at $\sim1.5$ kpc from the Sun, a distance consistent with that of the Sgr-Car arm in that direction. This low-absorption window allows one to probe into distant parts of the disk besides the Sgr-Car arm, probably the tangent part of the Sct-Cru arm, and/or the far side of the Sgr-Car arm in that direction. The main sequence associated to the Sgr-Car arm is reddened by $\ebv\sim0.5$, so that this window through the disk is comparable in reddening to Baade's window to the bulge. We also investigate the nature of the open cluster candidate Ru 166. The presently available data do not allow us to conclude whether Ru 166 is an actual open cluster or field stars seen through a small-scale low-absorption window.