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Lithium Isotopes In Population Ii Dwarfs

机译:Population族矮中的锂同位素

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We address the evolution of lithium in Population II dwarf stars under the joint effects of microscopic diffusion and tachocline mixing. This process relies on analytical developments and is also constrained by helioseismology observations. It was successfully applied to solar analogs but never investigated in halo stars. It is induced in the upper radiation zone by rotation and a slight differential rotation in latitude. Consequently we modeled different possible rotation histories of halo stars, showing that the initial rotation rate had no impact on lithium in the framework of tachocline mixing. We find a negligible impact of pre-main-sequence evolution on ~7Li independent of metallicity provided that [Fe/H] < - 1. On the contrary, microscopic diffusion and tachocline turbulence act on the long term of main sequence and shape the current ~7Li-T_(eff) pattern from the turnoff down to 5000 K. The tachocline mixing models fit the ~7LI-T_(eff) relation better than the pure microscopic diffusion models. We address the issue of warm ~7Li-poor stars and conclude that a moderate mass transfer from a companion could explain their composition. Finally, we discuss the lithium lighter isotope. The pre-main-sequence and main-sequence ~6Li depletion we compute seems difficult to reconcile with the current observations.
机译:我们研究了微观扩散和速可控混合效应共同作用下种群II矮星中锂的演化。这个过程依赖于分析的发展,并且还受到日震学观察的限制。它已成功应用于太阳类似物,但从未在光晕星中进行过研究。它是通过旋转和纬度的轻微差异旋转而在上部辐射区中引起的。因此,我们对晕星的各种可能的自转历史进行了建模,显示出在转速混合过程中,初始自转速度对锂没有影响。只要[Fe / H] <-1,我们发现主序前演化对〜7Li的影响与金属无关,可以忽略不计。相反,微观扩散和Tachocline湍流作用于主序的长期影响电流的形状。从关闭到低至5000 K的〜7Li-T_(eff)模式。速动混合模型比纯微观扩散模型更适合〜7LI-T_(eff)关系。我们解决了约7Li贫乏恒星的问题,并得出结论,来自同伴的适度传质可以解释其组成。最后,我们讨论了锂打火机的同位素。我们计算出的主主序列前和主序列约6Li耗尽似乎难以与当前观察值相吻合。

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  • 来源
    《The Astrophysical journal》 |2008年第2apart1期|1279-1288|共10页
  • 作者

    L. Plau;

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