Lithium and Beryllium in One-solar-mass Stars
Lithium and Beryllium in One-solar-mass Stars
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DOI：
10.3847/1538-4357/ac9625
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发表时间：
2022-09
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影响因子：
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通讯作者：
A. Boesgaard;C. Deliyannis;Michael G. Lum;A. Chontos
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作者：
A. Boesgaard;C. Deliyannis;Michael G. Lum;A. Chontos
恒星表面锂（Li）和铍（Be）的含量可以揭示恒星内部温度结构和物理过程的重要信息。这项研究的重点是太阳型恒星，其样本比以前更精确地定义。我们选择的Be恒星受到五个参数的限制：质量、温度、表面重力、金属丰度和年龄，这些参数与太阳相似，并且集中在±0.02的1 M以内。我们使用Keck I望远镜和HIRES获得了52颗这样的恒星在高光谱分辨率（45，000）和高信噪比下的Be ii光谱区域的光谱。虽然这些恒星中Li的扩散大于400倍，但Be的扩散仅为2.7倍。两颗恒星没有任何Be，可能是由于合并或与伴星的质量转移。我们发现Li随温度的变化趋势很陡，而Be的变化趋势很小。虽然Li与[Fe/H]从−0.4到+0.4有下降趋势，但由于恒星的耗尽，Be与Fe的关系略有增加。虽然Li随着年龄的增长而广泛下降，但Be可能会随着年龄的增长而小幅增加，尽管年龄的确定性较差。在最接近太阳的温度和其他参数的恒星的子集，我们发现，丰度的比例是锂远低于模型预测，可能有其他混合机制造成额外的锂耗尽。
The surface content of lithium (Li) and beryllium (Be) in stars can reveal important information about the temperature structure and physical processes in their interior regions. This study focuses on solar-type stars with a sample that is more precisely defined than done previously. Our selection of stars studied for Be is constrained by five parameters: mass, temperature, surface gravity, metallicity, and age to be similar to the Sun and is focused on stars within ±0.02 of 1 M ⊙. We have used the Keck I telescope with HIRES to obtain spectra of the Be ii spectral region of 52 such stars at a high spectral resolution (∼45,000) and high signal-to-noise ratios. While the spread in Li in these stars is greater than a factor of 400, the spread in Be is only 2.7 times. Two stars were without any Be, perhaps due to a merger or a mass transfer with a companion. We find a steep trend of Li with temperature but little for Be. While there is a downward trend in Li with [Fe/H] from −0.4 to +0.4 due to stellar depletion, there is a small increase in Be with Fe from Galactic Be enrichment. While there is a broad decline in Li with age, there may be a small increase in Be with age, though age is less well determined. In the subset of stars closest to the Sun in temperature and other parameters, we find that the ratio of the abundances of Be to Li is much lower than predicted by models; there may be other mixing mechanisms causing additional Li depletion.