EFFECTS OF MAGNETIC FIELDS ON LITHIUM EVOLUTION IN F AND G STARS
EFFECTS OF MAGNETIC FIELDS ON LITHIUM EVOLUTION IN F AND G STARS
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DOI：
10.1088/0004-637x/781/2/62
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发表时间：
2014-01
期刊：
影响因子：
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通讯作者：
T. Li;Shaolan Bi;Wuming Yang;K. Liu;Zhijia Tian;Z. Ge
中科院分区：
文献类型：
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作者：
T. Li;Shaolan Bi;Wuming Yang;K. Liu;Zhijia Tian;Z. Ge
为了研究磁场对锂耗尽的影响，并解释疏散星团中F型和G型恒星锂演化的特征，我们构建了一个包含Tayler-Spruit发电机型场的恒星模型.通过考察恒星内部磁场引起的额外混合的特征以及锂耗尽与输入参数（即，质量，金属丰度，和初始旋转条件），我们发现，磁模型产生额外的混合过程不同于其他模型。在主序前，该模型表现出非常有效的额外混合，导致强烈的锂贫化。随着星星的演化，额外混合的效率迅速降低，锂的消耗在年老时减缓。通过设置不同的初始旋转条件，该模型预测了主序和前主序阶段锂丰度的离散度。当辐射核在内部形成时，散射开始。之后，这一数字迅速增长，在G星和晚F星的零龄主序星上达到0.1-0.5 dex。色散在主序星中继续增加，在G星和晚F星中增加很小，而在中F星中增加很大。最后，对四个疏散星团的观测数据和理论结果进行了比较。达成了良好的协议。
To study the effects of magnetic fields on lithium depletion and to explain the characteristics of lithium evolution in F- and G-type stars in open clusters, we construct a stellar model that includes a Tayler–Spruit dynamo-type field. Through examining the features of extra-mixing caused by magnetic fields in stellar interiors and the relationship between lithium depletion and the input parameters (i.e., mass, metallicity, and the initial rotational condition), we find that the magnetic model produces extra-mixing processes different from other models. During pre-main sequence, the model exhibits very efficient extra-mixing, resulting in strong lithium depletion. As a star evolves, the efficiency of extra-mixing rapidly decreases and lithium depletion slows down at old ages. By setting up different initial rotating conditions, the model predicts dispersions of lithium abundance in both main sequence and pre-main sequence stages. The dispersion begins when a radiative core forms in the interior. The number sees a rapid growth afterward, reaching 0.1–0.5 dex at zero age main sequence in G and late-F stars. The increase of dispersion continues in the main sequence, which is slight in G and late-F stars while significant in mid-F stars. Finally, a comparison is carried out between the theoretical results and the observed data in four open clusters. Good agreements are obtained.