Oxygen and magnesium abundance in the ultra-metal-poor giants CS 22949-037 and CS 29498-043:: Challenges in models of atmospheres

被引:23
作者
Israelian, G [1 ]
Shchukina, N
Rebolo, R
Basri, G
Hernández, JIG
Kajino, T
机构
[1] Inst Astrofis Canarias, Tenerife 38205, Spain
[2] Natl Acad Sci Ukraine, Main Astron Observ, UA-03680 Kiev 127, Ukraine
[3] Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA
[4] Natl Astron Observ Japan, Tokyo 1818588, Japan
来源
ASTRONOMY & ASTROPHYSICS | 2004年 / 419卷 / 03期
关键词
Galaxy : evolution; nuclear reactions; nucleosynthesis; abundances; stars : abundances; stars : late-type; stars : population III; stellar atmospheres;
D O I
10.1051/0004-6361:20035785
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We report the results of a non-LTE Fe, O and Mg abundance analysis of the carbon-nitrogen-rich ultra-metal-poor giants CS 29498-043 and CS 22949-037. The abundance of oxygen has been derived from measurements of the oxygen triplet at 7771-5 Angstrom in high resolution spectra obtained with KeckI/HIRES and the forbidden line [O I] 6300 Angstrom detected in the TNG/SARG spectra of CS 29498-043. Detailed non-LTE analysis of Fe lines has provided reliable stellar parameters which, however, do not resolve the oxygen abundance conflict as derived from the O I 7771-5 Angstrom triplet and the [O I] 6300 Angstrom forbidden lines. We obtained the following oxygen abundance: for CS 22949-037 [O/Fe] = 3.13, 1.95; and for CS 29498-043; [O/Fe] = 3.02, 2.49, based on the O I 7771-5 Angstrom triplet and the [O I] 6300 Angstrom forbidden line, respectively. A similar conflict appears to exist between the forbidden resonance line Mg 14571 Angstrom and several subordinate lines, such as Mg 15172 and 5183 Angstrom. Our analysis demonstrates the failure of standard plane-parallel atmosphere models to describe the physical conditions in the line-forming regions of these ultra-metal-poor giants.
引用
收藏
页码:1095 / 1109
页数:15
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