LS 4825: A Blue Supergiant on the Far Side of the Galaxy
LS 4825: A Blue Supergiant on the Far Side of the Galaxy
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LS 4825：银河系远端的蓝色超巨星
DOI：
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
K. Venn
中科院分区：
文献类型：
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作者：
R. Ryans;P. Dufton;F. Keenan;S. Smartt;K. Sembach;D. Lennon;K. Venn
本文对银河系中心方向的一颗V = 12的B型星星LS 4825进行了高分辨率光谱观测。根据它的恒星光谱和星际光谱，我们推断它可能是一颗年轻的超巨星，距离为21 ± 5 kpc，因此位于银河系的远端。采用这一假设，差分丰度分析显示LS 4825的化学成分与当地的B型超巨星一致。因此，这些观测结果代表了对银河系中心远端星星的首次详细调查。我们追踪了Ca II K和Na I D光谱中的多个星际成分，速度为-206 ≤ vlsr ≤ +93 km s-1。我们考虑了这种气体的可能来源，并发现一些成分似乎是靠近银河系中心的物质。我们讨论了可能使用这样的视线，以进一步了解银河系中心周围的气体的性质和银河系的丰度梯度。
We present high-resolution spectroscopic observations of LS 4825, a V = 12 B-type star in the Galactic center direction. On the basis of its stellar and interstellar spectra, we infer that it is likely to be a young supergiant at a distance of 21 ± 5 kpc, and hence lying on the far side of the Galaxy. Adopting this hypothesis, a differential abundance analysis shows LS 4825 to have a chemical composition that is consistent with local B-type supergiants. These observations therefore represent the first detailed investigation of a star on the far side of the Galactic center. We trace multiple interstellar components in Ca II K and Na I D spectra, with velocities -206 ≤ vlsr ≤ +93 km s-1. We consider the likely origin of this gas and find that some components appear to trace matter lying close to the Galactic center. We discuss the possible use of such sight lines in furthering our understanding both of the nature of gas around the Galactic center and of the abundance gradient of the Galaxy.