Hot Subdwarf Stars Observed in Gaia DR2 and LAMOST DR5
Hot Subdwarf Stars Observed in Gaia DR2 and LAMOST DR5
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在 Gaia DR2 和 LAMOST DR5 中观测到的热亚矮星
DOI：
10.3847/1538-4357/ab298d
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发表时间：
2019-06
期刊：
影响因子：
--
通讯作者：
Zhanwen Han
中科院分区：
文献类型：
--
作者：
Yangping Luo;Péter Németh;Licai Deng;Zhanwen Han
结合Gaia DR 2和LAMOST DR 5，我们在光谱上识别了924颗热亚矮星，其中32颗星表现出强烈的双线复合光谱。我们测量了有效温度Teff，表面重力，氦丰度y = nHe/nH，径向速度（RV）的892个非复合光谱热亚矮星的LAMOST观测与Tlusty/Synspec非LTE合成光谱拟合。我们用氦丰度分类方案在图中概述了四个不同的组，图中有两个几乎平行的序列。使用LAMOST RV和盖亚的弛豫和自行计算了747颗（GBP − GRP）0 < −0.36等的热亚矮星的3D银河系空间运动和轨道。基于U-V速度图、Jz-偏心率图和银河系轨道，我们推导出了银河系种群分类以及晕、薄盘和厚盘中四个热亚矮氦群的分数分布。与双星星族合成计算结果的比较表明，富氦热亚矮星来自于双氦白色矮星（HeWDs）并合，贫氦热亚矮星来自于共包层抛射，而贫氦热亚矮星来自于稳定的洛希瓣溢出通道.在薄盘中，具有和处于晕中的富He热亚矮星的相对数量是Zhang等人预测的2倍多，是6倍多，这意味着HeWDs与低质量主序星的合并可能不是富He热亚矮星的主要形成通道，特别是在较年轻的环境中。
Combing Gaia DR2 with LAMOST DR5, we spectroscopically identified 924 hot subdwarf stars, among which 32 stars exhibit strong double-lined composite spectra. We measured the effective temperature Teff, surface gravity , helium abundance y = nHe/nH, and radial velocities (RVs) of 892 non-composite spectra hot subdwarf stars by fitting LAMOST observations with Tlusty/Synspec non-LTE synthetic spectra. We outlined four different groups in the diagram with our helium abundance classification scheme and two nearly parallel sequences in the diagram. 3D Galactic space motions and orbits of 747 hot subdwarf stars with (GBP − GRP)0 < −0.36 mag were computed using LAMOST RVs and Gaia parallaxes and proper motions. Based on the U − V velocity diagram, Jz−eccentricity diagram, and Galactic orbits, we derived Galactic population classifications and the fractional distributions of the four hot subdwarf helium groups in the halo, thin disk, and thick disk. Comparisons with the predictions of binary population synthesis calculations suggest that He-rich hot subdwarf stars with are from the double helium white dwarfs (HeWDs) merger, He-deficient hot subdwarf stars with from the common envelope ejection, and He-deficient hot subdwarf stars with from the stable Roche lobe overflow channels. The relative number of He-rich hot subdwarf stars with and in the halo is more than twice the prediction of Zhang et al. by more than six times in the thin disk, which implies that the mergers of HeWDs with low-mass main-sequence stars may not be the main formation channel for He-rich hot subdwarf stars with , especially in younger environments.
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DOI：
10.1046/j.1365-8711.2002.05752.x
发表时间：
2002-06
影响因子：
4.8
作者：
Zhanwen Han;P. Podsiadlowski;P. Maxted;T. Marsh;N. Ivanova
通讯作者：
Zhanwen Han;P. Podsiadlowski;P. Maxted;T. Marsh;N. Ivanova
设置场景
DOI：
10.1002/9781119581161.ch1
发表时间：
2019
期刊：
Stroke Nursing
影响因子：
--
作者：
C. Watkins;D. Cadilhac
通讯作者：
D. Cadilhac
DOI：
10.1086/152878
发表时间：
1974-06
期刊：
The Astrophysical Journal
影响因子：
--
作者：
D. Mihalas;A. J. Barnard;J. Cooper;Earl W. Smith
通讯作者：
D. Mihalas;A. J. Barnard;J. Cooper;Earl W. Smith
影响因子：
4.8
作者：
C. Byrne;C. Jeffery;C. Tout;Haili Hu
通讯作者：
C. Byrne;C. Jeffery;C. Tout;Haili Hu
影响因子：
4.8
作者：
H. Saio;C. Jeffery
通讯作者：
H. Saio;C. Jeffery