A DOUBLE MAIN SEQUENCE IN THE GLOBULAR CLUSTER NGC 6397

被引：90
|
作者：
Milone, A. P. [1 ,2 ]
Marino, A. F. [3 ]
Piotto, G. [4 ,5 ]
Bedin, L. R. [6 ]
Anderson, J. [6 ]
Aparicio, A. [1 ,2 ]
Cassisi, S. [7 ]
Rich, R. M. [8 ]
机构：
[1] Inst Astrofis Canarias, E-38200 San Cristobal la Laguna, Tenerife, Spain
[2] Univ La Laguna, Dept Astrophys, E-38200 San Cristobal la Laguna, Tenerife, Spain
[3] Max Planck Inst Astrophys, D-85741 Garching, Germany
[4] Univ Padua, Dipartimento Astron, I-35122 Padua, Italy
[5] INAF Osservatorio Astron Padova, I-35122 Padua, Italy
[6] Space Telescope Sci Inst, Baltimore, MD 21218 USA
[7] INAF Osservatorio Astron Collurania, I-64100 Teramo, Italy
[8] Univ Calif Los Angeles, Div Astron & Astrophys, Los Angeles, CA 90095 USA
来源：
ASTROPHYSICAL JOURNAL | 2012年 / 745卷 / 01期
关键词：
globular clusters: individual (NGC 6397); stars: Population II; MULTIPLE STELLAR POPULATIONS; ADVANCED CAMERA; OMEGA-CENTAURI; GIANT STARS; ACS SURVEY; ABUNDANCES; NGC-6397; BRANCH; ASTROMETRY; NGC-2808;
D O I：
10.1088/0004-637X/745/1/27
中图分类号：
P1 [天文学];
学科分类号：
0704 ;
摘要：
High-precision multi-band Hubble Space Telescope (HST) photometry reveals that the main sequence of the globular cluster NGC 6397 splits into two components, containing similar to 30% and similar to 70% of the stars. This double sequence is consistent with the idea that the cluster hosts two stellar populations: (1) a primordial population that has a composition similar to field stars, containing similar to 30% of the stars, and (2) a second generation with enhanced sodium and nitrogen, depleted carbon and oxygen, and a slightly enhanced helium abundance (Delta Y similar to 0.01). We examine the color difference between the two sequences across a variety of color baselines and find that the second sequence is anomalously faint in m(F336W). Theoretical isochrones indicate that this could be due to NH depletion.
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页数：10
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