LAMOST J101356.33+272410.7: A Detached White Dwarf-Main-sequence Binary with a Massive White Dwarf Within the Period Gap

TL;DR

This paper analyzes a detached binary system with a massive white dwarf and a main-sequence star, providing detailed stellar parameters and suggesting its evolutionary status as a post-common-envelope binary likely to become a cataclysmic variable.

Contribution

The study presents detailed characterization of a unique white dwarf-main sequence binary within the period gap, including mass, radius, and temperature measurements, and discusses its evolutionary implications.

Findings

White dwarf mass of 1.05 solar masses

Main-sequence star mass of 0.299 solar masses

System predicted to become a cataclysmic variable in 0.27 Gyr

Abstract

We report the analysis of the detached eclipsing spectroscopic binary system LAMOST J101356.33+272410.7, which features a massive white dwarf. Using LAMOST and SDSS spectra, we determined the stellar parameters and radial velocities of both components. SED fitting of photometric data from GALEX, 2MASS, and Pan-STARRS1 yielded the effective temperatures and photometric radii. Eclipsing analysis of high-speed photometric data from the Liverpool Telescope provided orbital inclination, masses, radii, and related physical parameters. The white dwarf in this system has a mass of $1.05 \pm 0.09 \, M_\odot$ and a radius of $0.0090 \pm 0.0008 \, R_\odot$, while the main-sequence star has a mass of $0.299 \pm 0.045 \, M_\odot$ and a radius of $0.286 \pm 0.018 \, R_\odot$. Emission lines observed in the spectra indicate the likely presence of stellar magnetic activity in this system. The relatively cool temperature of the white dwarf suggests that the system could be a post-common-envelope binary (PCEB) that has not undergone mass transfer, while the presence of a massive white dwarf indicates that the system might also represent a detached cataclysmic variable (dCV) crossing the period gap. We suggest that the system is more likely to be a PCEB, and it is predicted to evolve into a cataclysmic variable and begin mass transfer in approximately 0.27 Gyr.