The radial distribution of the two stellar populations in NGC 1851
The radial distribution of the two stellar populations in NGC 1851
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DOI：
10.1051/0004-6361/200912256
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发表时间：
2009-06
影响因子：
6.5
通讯作者：
A. Milone;P. Stetson;G. Piotto;L. Bedin;Jay Anderson;S. Cassisi;M. Salaris
中科院分区：
文献类型：
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作者：
A. Milone;P. Stetson;G. Piotto;L. Bedin;Jay Anderson;S. Cassisi;M. Salaris
我们分析了ACS/WFC和WFPC 2的图像从HST，以及地面数据，以研究最近发现的银河系球状星团NGC 1851中的双亚巨星分支（SGB）的径向分布。我们发现，SGB分裂可以从集群中心一直到距离中心至少8英尺的地方。超过这个距离，潮汐半径约为11.7弧分，SGB星太少，无法识别序列。亮星与暗星的数量比没有明显的径向趋势。此外，我们还发现，从星团中心到外包络，蓝色水平分支（HB）星加上天琴座RR星与红色HB星的比例也保持不变。
We have analyzed ACS/WFC and WFPC2 images from HST , as well as ground-based data to study the radial distribution of the double sub-giant branch (SGB) recently discovered in the Galactic globular cluster NGC 1851. We found that the SGB split can be followed all the way from the cluster center out to at least 8´ from the center. Beyond this distance out to the tidal radius at ~11.7 arcmin, there are simply too few SGB stars to identify the sequences. The number ratio of the bright SGB to the faint SGB stars shows no significant radial trend. Furthermore, we have found that the ratio of blue horizontal-branch (HB) stars plus RR Lyrae to the red HB stars also remains constant from the cluster center to the outer envelope.