Search for DA White Dwarf Binary Candidates from LAMOST DR7
Hua-Hui Yan,
Jing-Kun Zhao,
Wei-Bin Shi,
Jin-Cheng Guo,
Liang Wang,
Zhen-Xin Lei,
Gang Zhao
Affiliations
Hua-Hui Yan
Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, School of Space Science and Physics, Shandong University, Weihai 264209, China
Jing-Kun Zhao
CAS Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, China
Wei-Bin Shi
Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, School of Space Science and Physics, Shandong University, Weihai 264209, China
Jin-Cheng Guo
Department of Scientific Research, Beijing Planetarium, Xizhimenwai Street, Beijing 100044, China
Liang Wang
National Astronomical Observatories, Nanjing Institute of Astronomical Optics & Technology, Chinese Academy of Sciences, Nanjing 210042, China
Zhen-Xin Lei
Laboratory of Stars and Interstellar Medium, Xiangtan University, Xiangtan 411105, China
Gang Zhao
CAS Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, China
We obtained spectroscopy data for 761 Degenerate A (DA)white dwarfs (WDs) with multiple LAMOST observations. The radial velocity (RV) of each spectrum was calculated using the cross-correlation function method (CCF), and 60 DA WD binary candidates were selected based on the variation of the RV. Then, the atmosphere parameter Teff, logg, and the mass of these DA WDs were estimated by the Balmer line fitting method and interpolation in theoretical evolution tracks, respectively. Our parameters are consistent with those from SDSS and Gaia for the common stars. No evident difference in the mass distribution of binary candidates compared with total DA WDs was found. We surmise these DA WD binary candidates are mainly composed of two WDs. With the Zwicky Transient Facility (ZTF) data, we obtained the light curve periods of two targets with significant light curve periods in the DA WD binary candidates. For the spectra with anomalous CCF curves or with large errors in their RV calculations, we re-certified their spectral types by visual review. Based on their spectral features, we found 11 DA + M-type binaries and four cataclysmic variables (CVs). The light curve period of one CV was obtained with ZTF data.