arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1209.2591astro-ph.SRastro-ph.GA
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附近年轻星协中低质量恒星的元素丰度:AB Doradus、Carina Near和Ursa Major

Elemental abundances of low-mass stars in nearby young associations: AB Doradus, Carina Near, and Ursa Major

K. Biazzo, V. D'Orazi, S. Desidera, E. Covino, J. M. Alcalá, M. Zusi

摘要:

本文给出了剑鱼座AB、船底座近、大熊座三个年轻星群中13颗F6-K2主序星的恒星参数和11种元素(Li、Na、Mg、Al、Si、Ca、Ti、Cr、Fe、Ni和Zn)的丰度。外行星宿主星<$Horolosium也被分析。这三个年轻的协会具有与其年龄一致的锂丰度。所有其他元素都显示出太阳丰度。这三个类群的特征是在所有丰度上都有小的分散,剑鱼座AB、隆突近和大熊座AB的平均[Fe/H]值分别为0.10(σ= 0.03)、0.08(σ=0.05)和0.01(σ=0.03)dex。元素丰度的分布似乎与太阳附近的银河系薄盘的化学模式一致,就像在其他年轻群体中发现的那样。这意味着,作为直接成像行星搜索巡天目标的邻近年轻恒星的金属丰度分布,不同于作为径向速度巡天典型目标的老的太阳型恒星。年轻的行星母星<$Horoloeu的锂丰度低于年轻的星协成员。发现它的铁丰度略高于太阳值([Fe/H]=0.16+-0.09),而所有的[X/Fe]比值与太阳值相近。它的元素丰度接近毕宿星团,这似乎加强了与原始星团可能有共同起源的想法。

英文摘要:

We present stellar parameters and abundances of 11 elements (Li, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, and Zn) of 13 F6-K2 main-sequence stars in the young groups AB Doradus, Carina Near, and Ursa Major. The exoplanet-host star ιHorologii is also analysed. The three young associations have lithium abundance consistent with their age. All other elements show solar abundances. The three groups are characterised by a small scatter in all abundances, with mean [Fe/H] values of 0.10 (σ=0.03), 0.08 (σ=0.05), and 0.01 (σ=0.03) dex for AB Doradus, Carina Near, and Ursa Major, respectively. The distribution of elemental abundances appears congruent with the chemical pattern of the Galactic thin disc in the solar vicinity, as found for other young groups. This means that the metallicity distribution of nearby young stars, targets of direct-imaging planet-search surveys, is different from that of old, field solar-type stars, i.e. the typical targets of radial velocity surveys. The young planet-host star ιHorologii shows a lithium abundance lower than that found for the young association members. It is found to have a slightly super-solar iron abundance ([Fe/H]=0.16+-0.09), while all [X/Fe] ratios are similar to the solar values. Its elemental abundances are close to those of the Hyades cluster derived from the literature, which seems to reinforce the idea of a possible common origin with the primordial cluster.

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