arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1303.3418astro-ph.EP
收藏

具有行星的演化恒星的金属丰度特征

The metallicity signature of evolved stars with planets

J. Maldonado, E. Villaver, C. Eiroa

摘要:

我们确定在一个均匀的方式的金属丰度和个人的丰度的大样本的演化恒星,有和没有已知的行星同伴。我们的方法是基于高分辨率阶梯光谱的分析。金属丰度分布表明,拥有行星的巨恒星并不优先富含金属,其丰度模式与没有已知行星伴星的巨恒星相似。然而,我们已经发现,在这个样本中,金属丰度分布和恒星质量之间有很强的关系。结果表明,具有行星的质量较小的巨星(M < 1.5 Msun)并不富含金属,但是,具有行星的质量较大的(M > 1.5 Msun)、年龄小于2 Gyr的巨星样品的金属丰度要高于没有行星的类似恒星样品。至于其他化学元素,质量域M < 1.5 Msun的有行星和没有行星的巨星显示出类似的丰度模式。然而,质量M > 1.5 Msun的行星和非行星宿主在某些元素的丰度上显示出差异,特别是Na,Co和Ni。此外,我们发现样本的次巨星的行星是金属丰富的显示类似的金属丰度主序星主机。质量域M < 1.5 Msun的巨行星宿主没有金属富集的事实很难解释。鉴于这些恒星与次巨星和主序星的恒星参数相似,低质量巨星缺乏富含金属的特征可以解释为,如果起源于主序星中的污染场景,当恒星完全对流时被抹去。然而,没有物理上的理由说明它应该对质量为M1.5 Msun的巨星起作用< 1.5 Msun but is not observed for giants with M >。

英文摘要:

We determine in a homogeneous way the metallicity and individual abundances of a large sample of evolved stars, with and without known planetary companions. Our methodology is based on the analysis of high-resolution echelle spectra. The metallicity distributions show that giant stars hosting planets are not preferentially metal-rich having similar abundance patterns to giant stars without known planetary companions. We have found, however, a very strong relation between the metallicity distribution and the stellar mass within this sample. We show that the less massive giant stars with planets (M < 1.5 Msun) are not metal rich, but, the metallicity of the sample of massive (M > 1.5 Msun), young (age < 2 Gyr) giant stars with planets is higher than that of a similar sample of stars without planets. Regarding other chemical elements, giant stars with and without planets in the mass domain M < 1.5 Msun show similar abundance patterns. However, planet and non-planet hosts with masses M > 1.5 Msun show differences in the abundances of some elements, specially Na, Co, and Ni. In addition, we find the sample of subgiant stars with planets to be metal rich showing similar metallicities to main-sequence planet hosts. The fact that giant planet hosts in the mass domain M < 1.5 Msun do not show metal-enrichment is difficult to explain. Given that these stars have similar stellar parameters to subgiants and main-sequence planet hosts, the lack of the metal-rich signature in low-mass giants could be explained if originated from a pollution scenario in the main sequence that gets erased as the star become fully convective. However, there is no physical reason why it should play a role for giants with masses M < 1.5 Msun but is not observed for giants with M > 1.5 Msun.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑