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.

引用

页数：10

共 50 条

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