222 hot subdwarf stars were identified with LAMOST DR8 spectra, among which 131 stars show composite spectra and have been decomposed, while 91 stars present single-lined spectra. Atmospheric parameters of all sample stars were obtained by fitting Hydrogen (H) and Helium (He) line profiles with synthetic spectra. Two long-period composite sdB binaries were newly discovered by combining our sample with the non-single star data from Gaia DR3. One of the new systems presents the highest eccentricity (i.e., 0.5 +/- 0.09) among known wide sdB binaries, which is beyond model predictions. 15 composite sdB stars fall in the high probability binary region of RUWE-AEN plane, and deserve priority follow-up observations to further study their binary nature. A distinct gap is clearly presented among temperatures of cool companions for our composite-spectra sample. But we could not come to a conclusion whether this feature is connected to the formation history of hot subdwarf stars before their binary natures are confirmed.
@article{arxiv.2211.12323,
title = {Hot subdwarf stars identified in LAMOST DR8 with single-lined and composite spectra},
author = {Zhenxin Lei and Ruijie He and Peter Nemeth and Joris Vos and Xuan Zou and Ke Hu and Huaping Xiao and Huahui Yan and Jingkun Zhao},
journal= {arXiv preprint arXiv:2211.12323},
year = {2023}
}
Comments
21 pages, 11 figures, 3 tables, Accepted for publication in ApJ