The double subgiant branch of NGC 1851: The role of the CNO abundance

被引：127

作者：

Cassisi, S. ^{[1
]}

Salaris, M. ^{[2
,3
]}

Pietrinferni, A. ^{[1
]}

Piotto, G. ^{[4
]}

Milone, A. P. ^{[4
]}

Bedin, L. R. ^{[5
]}

Anderson, J. ^{[6
]}

机构：

[1] Osservat Astronm Collurania, INAF, I-64100 Teramo, Italy

[2] Liverpool John Moores Univ, Astrophys Res Inst, Birkenhead CH41 1LD, Merseyside, England

[3] Max Planck Inst Astrophys, D-85748 Garching, Germany

[4] Univ Padua, Dept Astron, I-35122 Padua, Italy

[5] Space Telescope Sci Inst, Baltimore, MD 21218 USA

[6] Rice Univ, Dept Phys & Astron, Houston, TX 77005 USA

来源：

ASTROPHYSICAL JOURNAL LETTERS | 2008年 / 672卷 / 02期

基金：

英国科学技术设施理事会;

关键词：

globular clusters : individual (NGC 1851); Hertzsprung-Russell diagram stars : abundances; stars : evolution;

D O I：

10.1086/527035

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We explore the possibility that the anomalous split in the subgiant branch (SGB) of the Galactic globular cluster NGC 1851 is due to the presence of two distinct stellar populations with very different initial metal mixtures: a normal alpha-enhanced component, and one characterized by strong anticorrelations among the CNONa abundances, with a total CNO abundance increased by a factor of 2. We test this hypothesis taking into account various empirical constraints, and conclude that the two populations should be approximately coeval, with the same initial He content. More high-resolution spectroscopic measurements of heavy elements - and in particular of the CNO sum - for this cluster are necessary to prove (or disprove) this scenario.

引用

页码：L115 / L118

页数：4

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