arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1902.07607astro-ph.SRastro-ph.GA
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LAMOST光谱巡天的OB星表

A Catalogue of OB Stars from LAMOST Spectroscopic Survey

Zhicun Liu, Wenyuan Cui, Chao Liu, Yang Huang, Gang Zhao, Bo Zhang

摘要:

我们给出了从LAMOST DR 5数据集中识别出的16\,032颗恒星的22\,901个OB谱。首先从谱线指数空间中的分布中选择OB候选的较大样本。然后通过人工检查识别所有221,901个OB光谱。通过子样验证发现,对于光谱类型早于B7的恒星,OB光谱的完整性达到了$89\pm22$ %左右,而B8-B 9恒星的完整性达到了$57\pm16$ %左右。晚B型星的完整性较小,导致其与A_0-A_1型星的鉴别困难。使用软件包MKCLASS确定OB样品的子类。通过对646个子样本的仔细验证,我们发现MKCLASS可以为大多数OB星提供相当可靠的子类型和光度级。光谱子类型的不确定性约为1个子类型,光度类别的不确定性约为1个级别。然而,大约40%的OB星没有被MKCLASS分类,少数光谱被MKCLASS错误分类。这可能是因为MKCLASS的模板光谱是从太阳附近的邻近恒星中选择的,而这项工作中的OB星大多位于外盘,可能具有较低的金属丰度。OB星的旋转也可能是错误分类的原因。此外,我们还发现位于银纬大于20 $^\circ$和小于20 $^\circ$的OB星的光谱和光度类有很大的不同,这可能是观测选择效应的结果,也可能暗示了高银纬OB星的不同起源。

英文摘要:

We present 22\,901 OB spectra of 16\,032 stars identified from LAMOST DR5 dataset. A larger sample of OB candidates are firstly selected from the distributions in the spectral line indices space. Then all 22\,901 OB spectra are identified by manual inspection. Based on a sub-sample validation, we find that the completeness of the OB spectra reaches about $89\pm22$\% for the stars with spectral type earlier than B7, while around $57\pm16$\% B8--B9 stars are identified. The smaller completeness for late B stars is lead to the difficulty to discriminate them from A0--A1 type stars. The sub-classes of the OB samples are determined using the software package MKCLASS. With a careful validation using 646 sub-samples, we find that MKCLASS can give fairly reliable sub-types and luminosity class for most of the OB stars. The uncertainty of the spectral sub-type is around 1 sub-type and the uncertainty of the luminosity class is around 1 level. However, about 40\% of the OB stars are failed to be assigned to any class by MKCLASS and a few spectra are significantly misclassified by MKCLASS. This is likely because that the template spectra of MKCLASS are selected from nearby stars in the solar neighborhood, while the OB stars in this work are mostly located in the outer disk and may have lower metallicity. The rotation of the OB stars may also be responsible for the mis-classifications. Moreover, we find that the spectral and luminosity classes of the OB stars located in the Galactic latitude larger than 20$^\circ$ are substantially different with those located in latitude smaller than 20$^\circ$, which may either due to the observational selection effect or hint a different origin of the high Galactic latitude OB stars.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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