贫金属晕矮星中的锂同位素，一个越来越复杂的故事
Li isotopes in metal-poor halo dwarfs, a more and more complicated story
摘要：
锂同位素的核很脆弱，很容易被破坏，因此，与大多数其他元素不同，它们不能通过稳定的流体静力核合成在恒星中形成。7 Li的同位素是在大爆炸后最初几分钟的原始核合成过程中合成的，后来又被宇宙射线、新星和AGB星的脉动（也可能是“nu”过程）合成。6Li主要由宇宙射线形成。最古老（最缺乏金属）的温暖星系恒星应该保留这些过程的签名，如果（正如人们经常预期的那样）锂在这些恒星中没有耗尽。讨论了在热贫金属星中存在7 Li丰度的“高原”（及其斜率）。在非常低的金属丰度（[Fe/H]<-2.7 dex）时，恒星与恒星之间的散射向低Li丰度方向显著增加。银河系早期恒星物质中锂丰度的最高值（A（7 Li）= 2.2 dex）远低于标准大爆炸核合成理论预测的A（7 Li）= 2.72。在收集了一个均匀的恒星样本，并分析其行为，可能的解释大爆炸和恒星丰度之间的分歧进行了讨论（包括早期astration和扩散）。另一方面，在标准和/或非标准的大爆炸核合成较低的生产7 Li的可能性被简要地唤起。在一些温暖的贫金属恒星中发现了令人惊讶的高丰度值（A（6Li）=0.8 dex）。如此高的6Li丰度与早期银河系的平均金属丰度无关，这是很难解释的。但我们真的在观察6Li吗？
英文摘要：
The nuclei of the lithium isotopes are fragile, easily destroyed, so that, at variance with most of the other elements, they cannot be formed in stars through steady hydrostatic nucleosynthesis. The 7Li isotope is synthesized during primordial nucleosynthesis in the first minutes after the Big Bang and later by cosmic rays, by novae and in pulsations of AGB stars (possibly also by the "nu" process). 6Li is mainly formed by cosmic rays. The oldest (most metal-deficient) warm galactic stars should retain the signature of these processes if, (as it had been often expected) lithium is not depleted in these stars. The existence of a "plateau" of the abundance of 7Li (and of its slope) in the warm metal-poor stars is discussed. At very low metallicity ([Fe/H]<-2.7 dex the star to star scatter increases significantly towards low Li abundances. The highest value of the lithium abundance in the early stellar matter of the Galaxy (A(7Li) = 2.2 dex) is much lower than the the value A(7Li) = 2.72 predicted by the standard Big Bang nucleosynthesis, according to the specifications found by the satellite WMAP. After gathering a homogeneous stellar sample, and analysing its behaviour, possible explanations of the disagreement between Big Bang and stellar abundances are discussed (including early astration and diffusion). On the other hand, possibilities of lower productions of 7Li in the standard and/or non-standard Big Bang nucleosyntheses are briefly evoked. A surprisingly high value (A(6Li)=0.8 dex) of the abundance of the 6Li isotope has been found in a few warm metal-poor stars. Such a high abundance of 6Li independent of the mean metallicity in the early Galaxy cannot be easily explained. But are we really observing 6Li ?
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