地面CCD天体测量与宽视场成像仪。III。半人马座球状星团的WFI m自行星表
Ground-based CCD astrometry with wide field imagers. III. WFI@2.2m proper-motion catalog of the globular cluster omega Centauri
摘要：
半人马座欧米茄是研究得最好的球状星团，因为它有许多令人困惑的特征。密集的光谱跟踪观测活动针对颜色-星等图上不同位置的恒星，有望澄清其中的一些特点。为了能够在光谱测量期间可靠地瞄准星团成员，以及在不包括场星的情况下在星团外围的空间和径向分布，需要欧米茄Cen的高质量自行目录和成员概率确定。唯一可用的ω Cen的宽视场自行星表是从照相底片上获得的，并且只适用于比B~16亮的恒星。利用ESO的存档数据，我们为这个星系团建立了一个新的基于CCD的自行星表，扩展到B~20。我们使用了专门为WFI@2.2米望远镜采集的数据开发的高精度天体测量软件，并在本系列的第一篇论文中提出。我们实现了一个很好的集群场分离的时间基线只有四年。我们校正了测光的天空浓度效应。我们提供了校准测光UBVRI宽波段数据加窄带滤波数据集中在H_α的近36万颗恒星。我们可以证实，ω Cen贫金属和富金属的成分有相同的自行，并证明金属中间的成分，此外表现出相同的平均运动作为其他RGB星。我们提供了成员概率测定公布的欧米茄Cen变星目录。我们的星表将自行测量扩展到比星团关闭光度更暗的范围，并覆盖了围绕欧米茄中心的广阔区域（~33'x33'）。我们的星表现在可以通过电子方式提供给天文学界。
英文摘要：
Omega Centauri is the most well studied Globular Cluster because of its numerous puzzling features. Intensive spectroscopic follow-up observing campaigns targeting stars at different positions on the color-magnitude diagram promises to clarify some of these peculiarities. To able to target cluster members reliably during spectroscopic surveys and both spatial and radial distributions in the cluster outskirts without including field stars, a high quality proper-motion catalog of omega Cen and membership probability determination are required. The only available wide field proper-motion catalog of omega Cen is derived from photographic plates, and only for stars brighter than B~16. Using ESO archive data, we create a new, CCD-based, proper-motion catalog for this cluster, extending to B~20. We used the high precision astrometric software developed specifically for data acquired by WFI@2.2m telescope and presented in the first paper of this series. We achieved a good cluster-field separation with a temporal base-line of only four years. We corrected our photometry for sky-concentration effects. We provide calibrated photometry for UBVRI wide-band data plus narrow-band filter data centered on H_alpha for almost 360 000 stars. We can confirm that the omega Cen metal-poor and the metal-rich components have the same proper motion, and demonstrate that the metal-intermediate component in addition exhibits the same mean motion as the other RGB stars. We provided membership probability determination for published omega Cen variable star catalogs. Our catalog extends the proper-motion measurements to fainter than the cluster turn-off luminosity, and covers a wide area (~33'x33') around the center of omega Cen. Our catalog is now electronically available to the astronomical community.
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