Limits on the Boron Isotopic Ratio in HD 76932
Limits on the Boron Isotopic Ratio in HD 76932
复制标题
HD 76932 中硼同位素比的限制
DOI：
10.1086/306315
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
B. Fields
中科院分区：
文献类型：
--
作者：
L. Rebull;D. Duncan;S. Johansson;J. Thorburn;B. Fields
HD 76932 λ2090 B区的数据是用哈勃空间望远镜戈达德高分辨率光谱仪中阶梯光栅以高信噪比获得的，分辨率为90，000。这个波长区域先前已被确定为观察11B/10 B同位素分裂的可能候选者。在任何丰度下，任何同位素比率的观测结果与计算的谱线轮廓都不匹配。如果假定先前从λ2500处的观测确定的B丰度，则计算的线轮廓太弱，指示可能的混合线。假设在λ2090处的吸收完全是由于硼，则最佳拟合的总B丰度高于在λ2500处获得的丰度，但与在λ2500处获得的丰度一致，并且最佳拟合的同位素比（11 B/10 B）在~10：1至~4：1的范围内。如果吸收不完全是由于B，并且存在未知的混合物，则最佳拟合同位素比可能更接近1：1。未来对类似的贫金属星星的观察，已知其B异常低，应该可以让我们区分这两种可能性。的限制，可以放置在同位素比的基础上与类似的观察HD 102870和HD 61421（南河三）的比较进行了讨论。
Data in the λ2090 B region of HD 76932 have been obtained at a high signal-to-noise ratio using the Hubble Space Telescope Goddard High-Resolution Spectrograph echelle at a resolution of 90,000. This wavelength region has been previously identified as a likely candidate for observing the 11B/10B isotopic splitting. The observations do not match a calculated line profile extremely well at any abundance for any isotopic ratio. If the B abundance previously determined from observations at λ2500 is assumed, the calculated line profile is too weak, indicating a possible blending line. Assuming that the absorption at λ2090 is entirely due to boron, the best-fit total B abundance is higher than, but consistent with, that obtained at λ2500, and the best-fit isotopic ratio (11B/10B) is in the range ~10:1 to ~4:1. If the absorption is not entirely due to B and there is an unknown blend, the best-fit isotopic ratio may be closer to 1:1. Future observations of a similar metal-poor star known to have unusually low B should allow us to distinguish between these two possibilities. The constraints that can be placed on the isotopic ratio based on comparisons with similar observations of HD 102870 and HD 61421 (Procyon) are also discussed.