Light element non-LTE abundances of λ Bootis stars

被引:34
|
作者
Kamp, I
Iliev, IK
Paunzen, E
Pintado, OI
Solano, E
Barzova, IS
机构
[1] Leiden Observ, NL-2300 RA Leiden, Netherlands
[2] Natl Astron Observ, Inst Astron, Smoljan 4700, Bulgaria
[3] Isaac Newton Inst Chile Bulgarian, Smoljan 4700, Bulgaria
[4] Univ Vienna, Inst Astron, A-1180 Vienna, Austria
[5] Univ Vienna, Zent Informat Dienst, A-1010 Vienna, Austria
[6] Univ Nacl Tucuman, Fac Ciencias Exactas & Tecnol, Dept Fis, Consejo Nacl Invest Cient & Tecn Republ Argentina, RA-4000 San Miguel De Tucuman, Tucuman, Argentina
[7] LAEFF, Madrid 28080, Spain
关键词
stars : abundances; stars : atmospheres; stars : chemically peculiar; stars : early-type;
D O I
10.1051/0004-6361:20010886
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
One of the main characteristics proclaimed for the group of the lambda Bootis stars is the apparent solar abundance of the light elements C, N, O and S. The typical abundance pattern is completed by the strong underabundances of the Fe-peak elements. In the first paper of this series, we have shown that carbon is less abundant than oxygen but both elements are still significantly more abundant than Fe-peak elements. The mean abundances, based on a detailed non-LTE investigation, were found -0.37 dex and -0.07 dex, respectively. As a further step, we now present non-LTE abundances of nitrogen and sulphur for thirteen members of the lambda Bootis group based on several spectral lines between 8590 Angstrom and 8750 Angstrom. Furthermore, LTE abundances for calcium in the same spectral range were derived and compared with values from the literature. Similar to the mean abundances of carbon and oxygen, nearly solar values were found (-0.30 dex for nitrogen and -0.11 dex for sulphur) for our sample of program stars. Among our sample, one previously undetected binary system (HD64491) was identified. From a statistical point of view, the abundances of the light elements range from slightly overabundant to moderately underabundant compared to the Sun. However, the individual objects always exhibit a similiar pattern, with the Fe-peak elements being significantly more underabundant than the light elements. No correlation of the derived abundances with astrophysical parameters such as the effective temperature, surface gravity or projected rotational velocity was found. Furthermore, the abundances of the light elements do not allow us to discriminate between any proposed theory.
引用
收藏
页码:899 / 908
页数:10
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