An abundance analysis of a chemically peculiar B star – JL 87
An abundance analysis of a chemically peculiar B star – JL 87
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对化学上奇特的 B 星 – JL 87 的丰度分析
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
V. Woolf
中科院分区：
文献类型：
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作者：
A. Ahmad;N. Behara;C. Jeffery;T. Şahin;V. Woolf
目标。本研究的目的是通过测量一颗化学性质奇特的星星JL 87的物理参数和化学丰度来了解它的性质和起源。方法.物理参数-有效温度，表面重力和氦丰度测量从中等分辨率的光谱使用完全线覆盖的LTE模型大气。通过比较FUSE、IUE分光光度法和光学/红外宽带光度法与LTE模型大气的理论通量分布，验证了有效温度和消光。光球化学丰度是使用LTE模型大气和光谱合成从高分辨率光谱测量的。结果根据它的物理参数和化学丰度，我们确认JL 87是一颗化学性质特殊的亚亮B星星。它比以前认为的要冷得多，表面重力较低，氦含量也更丰富。它的碳和氮含量中等，但其整体金属含量略低于太阳能。结论.白矮星冷却轨道上的晚期核心闪光的浅混合模型目前提供了与JL 87的可观测性质最一致的协议。
Aims. The aim of this study is to understand the nature and origin of a chemically peculiar star JL 87 by measuring its physical parameters and chemical abundances. Methods. Physical parameters – effective temperature, surface gravity and helium abundance were measured from a moderate resolution optical spectrum using fully line-blanketed LTE model atmospheres. The effective temperature and extinction were verified by comparing FUSE, IUE spectrophotometry and optical/IR broadband photometry with theoretical flux distributions from LTE model atmospheres. The photospheric chemical abundances were measured from a high-resolution optical spectrum using LTE model atmospheres and spectral synthesis. Results. On the basis of its physical parameters and chemical abundances, we confirm that JL 87 is a chemically peculiar subluminous B star. It is significantly cooler, has a lower surface gravity and is more helium-rich than previously believed. It is moderately enriched in carbon and nitrogen, but its overall metallicity is slightly subsolar. Conclusions. The shallow-mixing model of a late core-flash on a white-dwarf cooling track currently provides the most consistent agreement with the observable properties of JL 87.