Analysis of the carbon-rich very metal-poor dwarf G77-61

被引：93
|
作者：
Plez, B [1 ]
Cohen, JG
机构：
[1] Univ Montpellier 2, CNRS, GRAAL, UMR 5024, F-34095 Montpellier, France
[2] CALTECH, Palomar Observ, Pasadena, CA 91125 USA
来源：
ASTRONOMY & ASTROPHYSICS | 2005年 / 434卷 / 03期
基金：
美国国家科学基金会;
关键词：
stars : abundances; stars : carbon; stars : Population II; stars : individual : G77-61;
D O I：
10.1051/0004-6361:20042082
中图分类号：
P1 [天文学];
学科分类号：
0704 ;
摘要：
We present an analysis of the carbon dwarf G77-61, a known binary, based on high resolution Keck spectra. G77-61 has a very-low metallicity, although not as extreme as what was previously conjectured. This star is very carbon-enhanced, the spectra showing very strong CH, CN, and C-2 bands of both C-13 and C-12 isotopes. Atomic lines are sparse, and often blended, but we were able to derive abundances for Na, Mg, Ca, Cr, Mn, and Fe. Its [Fe/H] of -4.03 +/- 0.1 places it among the lowest metallicity stars known, and its very high [C/Fe] = +2.6, and [N/Fe] = +2.6 among the most C and N-rich metal-poor stars. The carbon isotopic ratio is C-12/C-13 = 5 +/- 1. No overabundance of s- or r-process elements is detectable, but the upper limits that can be set on these overabundances are not very constraining.
引用
收藏
页码：1117 / 1124
页数：8
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