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arXiv 1111.3495astro-ph.SRastro-ph.EP
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在有系外行星的冷主序星中Be丰度

Be abundances in cool main-sequence stars with exoplanets

E. Delgado Mena, G. Israelian, J. I. González Hernández, N. C. Santos, R. Rebolo

备注：
Accepted for publication in ApJ
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摘要：

我们提出了新的UVES光谱的样本15冷未进化的恒星和没有检测到行星的同伴。再加上以前的测定，我们研究的是耗尽和可能的差异，这两组恒星之间的丰度。我们获得了最终的样本89和40颗恒星，有和没有行星，分别涵盖了广泛的有效温度范围，从4700 K到6400 K，并首次包括几个冷矮星。我们确定这些恒星的丰度，并发现其中大多数（最酷的）的BeII共振线往往是不可检测的，这意味着显着的被耗尽。而对于热星，Be丰度是近似恒定的，随着Teff的减小和Li-Be间隙在6300 K附近略有下降，我们发现当Teff < 5500 K时，Be含量随着Teff的减小而急剧下降，证实了以前论文的结果。因此，对于这些恒星来说，有一种未知的机制在摧毁Be，而这种机制在当前的Be耗尽模型中没有反映出来。此外，无论是否存在行星，所有的恒星都会发生这种强烈的Be耗尽，因此，与没有探测到行星的恒星相比，具有行星的太阳型恒星中额外Li耗尽的影响似乎并不存在于Be中，尽管在这些温度下的恒星数量仍然很少，无法得出最终结论。

英文摘要：

We present new UVES spectra of a sample of 15 cool unevolved stars with and without detected planetary companions. Together with previous determinations, we study Be depletion and possible differences in Be abundances between both groups of stars. We obtain a final sample of 89 and 40 stars with and without planets, respectively, which covers a wide range of effective temperatures, from 4700 K to 6400 K, and includes several cool dwarf stars for the first time. We determine Be abundances for these stars and find that for most of them (the coolest ones) the BeII resonance lines are often undetectable, implying significant Be depletion. While for hot stars Be abundances are aproximately constant, with a slight fall as Teff decreases and the Li-Be gap around 6300 K, we find a steep drop of Be content as Teff decreases for Teff < 5500 K, confirming the results of previous papers. Therefore, for these stars there is an unknown mechanism destroying Be that is not reflected in current models of Be depletion. Moreover, this strong Be depletion in cool objects takes place for all the stars regardless of the presence of planets, thus, the effect of extra Li depletion in solar-type stars with planets when compared with stars without detected planets does not seem to be present for Be, although the number of stars at those temperatures is still small to reach a final conclusion.

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