Discovery and Characterization of White Dwarf-FGK Main-Sequence Binaries within the Optical Main-Sequence Locus

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Main Authors: Yang, Mingkuan, Yuan, Hailong, Yang, Xiaozhen, Bai, Zhongrui, He, Yuji, Xiong, Jianping, Li, Jiao, Wang, Mengxin, Dong, Yiqiao, Jiang, Ziyue, Liu, Qian, Li, Ganyu, Zhou, Ming, Zhang, Haotong, Chen, Xuefei
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Published: 2026
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author Yang, Mingkuan
Yuan, Hailong
Yang, Xiaozhen
Bai, Zhongrui
He, Yuji
Xiong, Jianping
Li, Jiao
Wang, Mengxin
Dong, Yiqiao
Jiang, Ziyue
Liu, Qian
Li, Ganyu
Zhou, Ming
Zhang, Haotong
Chen, Xuefei
author_facet Yang, Mingkuan
Yuan, Hailong
Yang, Xiaozhen
Bai, Zhongrui
He, Yuji
Xiong, Jianping
Li, Jiao
Wang, Mengxin
Dong, Yiqiao
Jiang, Ziyue
Liu, Qian
Li, Ganyu
Zhou, Ming
Zhang, Haotong
Chen, Xuefei
contents White dwarf main-sequence (WDMS) binaries provide important laboratories for studying binary evolution and the formation of low-mass white dwarfs. In this work, we identify 654 reliable WDMS candidates with FGK-type companions from an initial set of 772 ultraviolet-excess sources, selected using stellar atmospheric parameters from LAMOST spectroscopy and subsequently refined with \textit{Gaia} DR3 astrometry and photometry together with ultraviolet data from \textit{GALEX}. Candidates were selected based on ultraviolet excess relative to the \textit{Gaia} main-sequence locus and refined using isochrone constraints to exclude systems inconsistent with MS companions. Binary spectral energy distribution fitting yields effective temperatures and radii for both components, as well as distance and extinction estimates. The MS companions are dominated by G-type stars (\(\sim52\%\)), with comparable fractions of F- and K-type companions, and no A-type primaries. Using white-dwarf evolutionary cooling models, we find that the WD components are predominantly low-mass (\(M_{\rm WD}\,\sim\,0.2\text{--}0.4\,M_\odot\)), including a substantial population of extremely low-mass (\(<0.3\,M_\odot\)) WDs likely produced through binary interaction. The WDs are generally hot (\(\sim1.5\times10^4\,\mathrm{K}\)), consistent with the ultraviolet selection bias favoring luminous, large-radius WDs. Multi-epoch LAMOST radial velocities show larger amplitudes than those of a comparison sample of MS stars, supporting the close-binary nature of these systems. Although subject to strong selection effects, the catalog offers a clean and well-characterized sample of FGK+WD binaries.
format Preprint
id arxiv_https___arxiv_org_abs_2605_13112
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Discovery and Characterization of White Dwarf-FGK Main-Sequence Binaries within the Optical Main-Sequence Locus
Yang, Mingkuan
Yuan, Hailong
Yang, Xiaozhen
Bai, Zhongrui
He, Yuji
Xiong, Jianping
Li, Jiao
Wang, Mengxin
Dong, Yiqiao
Jiang, Ziyue
Liu, Qian
Li, Ganyu
Zhou, Ming
Zhang, Haotong
Chen, Xuefei
Solar and Stellar Astrophysics
White dwarf main-sequence (WDMS) binaries provide important laboratories for studying binary evolution and the formation of low-mass white dwarfs. In this work, we identify 654 reliable WDMS candidates with FGK-type companions from an initial set of 772 ultraviolet-excess sources, selected using stellar atmospheric parameters from LAMOST spectroscopy and subsequently refined with \textit{Gaia} DR3 astrometry and photometry together with ultraviolet data from \textit{GALEX}. Candidates were selected based on ultraviolet excess relative to the \textit{Gaia} main-sequence locus and refined using isochrone constraints to exclude systems inconsistent with MS companions. Binary spectral energy distribution fitting yields effective temperatures and radii for both components, as well as distance and extinction estimates. The MS companions are dominated by G-type stars (\(\sim52\%\)), with comparable fractions of F- and K-type companions, and no A-type primaries. Using white-dwarf evolutionary cooling models, we find that the WD components are predominantly low-mass (\(M_{\rm WD}\,\sim\,0.2\text{--}0.4\,M_\odot\)), including a substantial population of extremely low-mass (\(<0.3\,M_\odot\)) WDs likely produced through binary interaction. The WDs are generally hot (\(\sim1.5\times10^4\,\mathrm{K}\)), consistent with the ultraviolet selection bias favoring luminous, large-radius WDs. Multi-epoch LAMOST radial velocities show larger amplitudes than those of a comparison sample of MS stars, supporting the close-binary nature of these systems. Although subject to strong selection effects, the catalog offers a clean and well-characterized sample of FGK+WD binaries.
title Discovery and Characterization of White Dwarf-FGK Main-Sequence Binaries within the Optical Main-Sequence Locus
topic Solar and Stellar Astrophysics
url https://arxiv.org/abs/2605.13112