Mapping luminous hot stars in the Galaxy
Mapping luminous hot stars in the Galaxy
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DOI：
10.1051/0004-6361/202039726
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发表时间：
2021-02
影响因子：
6.5
通讯作者：
E. Zari;H. Rix;N. Frankel;M. Xiang;E. Poggio;R. Drimmel;A. Tkachenko
中科院分区：
文献类型：
--
作者：
E. Zari;H. Rix;N. Frankel;M. Xiang;E. Poggio;R. Drimmel;A. Tkachenko
[摘要]在整个宇宙学时间里，发光的热恒星主导着星际介质的恒星能量输入，它们是检验恒星演化和多重性理论的实验室，它们是银河系和其他星系中星星形成的发光示踪剂。大质量恒星在颜色-颜色和颜色-星等空间中占据明确的位置，即使在存在大量尘埃消光的情况下，也可以根据盖亚EDR 3天体测量和测光以及2 MASS测光的组合进行选择。在本文中，我们设计了一个这样的发光OBA型恒星的全天空样本，设计成相当完整，而不是非常纯净，作为SDSS-V调查的光谱跟踪目标。我们估计“天体运动学”的距离相结合的松弛和自行与预期的速度和密度分布的年轻恒星的模型，我们表明，这增加了有用的约束恒星的距离，因此光度。利用这些距离，我们绘制了银河系圆盘上一个更严格选择的子样本的空间分布，发现它是高度结构化的，具有明显的过密度和欠密度。最明显的超密度可能与银河系的螺旋臂有关，特别是人马座-船底座臂和盾牌座-半人马座臂。然而，这项研究中出现的银河系年轻圆盘结构的空间图像是复杂的，并表明我们银河系中的大多数年轻恒星（$t_{age}<t_{dyn}$）并没有整齐地组织成明显的螺旋臂。SDSS-V综合光谱的组合（产生速度，年龄等）。随着未来盖亚数据的发布，对于揭示旋臂本身的动力学性质将是至关重要的。
[Abridged] Luminous hot stars dominate the stellar energy input to the interstellar medium throughout cosmological time, they are laboratories to test theories of stellar evolution and multiplicity, and they serve as luminous tracers of star formation in the Milky Way and other galaxies. Massive stars occupy well-defined loci in colour-colour and colour-magnitude spaces, enabling selection based on the combination of Gaia EDR3 astrometry and photometry and 2MASS photometry, even in the presence of substantive dust extinction. In this paper we devise an all-sky sample of such luminous OBA-type stars, designed to be quite complete rather than very pure, to serve as targets for spectroscopic follow-up with the SDSS-V survey. We estimate "astro-kinematic" distances by combining parallaxes and proper motions with a model for the expected velocity and density distribution of young stars; we show that this adds useful constraints on the stars' distances, and hence luminosities. With these distances we map the spatial distribution of a more stringently selected sub-sample across the Galactic disc, and find it to be highly structured, with distinct over- and under-densities. The most evident over-densities can be associated with the presumed spiral arms of the Milky Way, in particular the Sagittarius-Carina and Scutum-Centaurus arms. Yet, the spatial picture of the Milky Way's young disc structure emerging in this study is complex, and suggests that most young stars in our Galaxy ($t_{age}<t_{dyn}$) are not neatly organised into distinct spiral arms. The combination of the comprehensive spectroscopy to come from SDSS-V (yielding velocities, ages, etc..) with future Gaia data releases will be crucial to reveal the dynamical nature of the spiral arm themselves.