Short-period Post-Common Envelope Binaries with Balmer Emission from SDSS and LAMOST Based on ZTF Photometric Data

TL;DR

This study identifies and characterizes 55 short-period post-common envelope binaries with white dwarf and low-mass star components using ZTF photometry, revealing new systems, refining periods, and discussing emission mechanisms.

Contribution

It reports the discovery of 6 new short-period PCEBs, improves orbital period measurements for 19, and identifies new eclipsing systems, expanding the known sample of these binaries.

Findings

Six new short-period PCEBs discovered.

Orbital periods range from 2.2643 to 81.1526 hours.

Emission features likely caused by stellar activity or irradiation.

Abstract

We present here 55 short period PCEBs containing a hot WD and a low-mass MS. Based on the photometric data from ZTF DR19, the light curves are analyzed for about 200 WDMS binaries with emission line(s) identified from SDSS or LAMOST spectra, in which 55 WDMS binaries are found to exhibit variability in their luminosities with a short period and are thus short-period binaries (i.e. PCEBs). In addition, it is found that the orbital periods of these PCEBs locate in a range from 2.2643 to 81.1526 hours. However, only 6 short-period PCEBs are newly discovered and the orbital periods of 19 PCEBs are improved in this work. Meanwhile, it is found that three objects are newly discovered eclipsing PCEBs, and a object (i.e. SDSS J1541) might be the short-period PCEB with a late M-type star or a brown dwarf companion based on the analysis of its spectral energy distribution. At last, the mechanism(s) being responsible for the emission features in the spectra of these PCEBs are discussed, the emission features arising in their optical spectra might be caused by the stellar activity or an irradiated component owing to a hot white dwarf companion because most of them contain a white dwarf with an effective temperature higher than $\sim$10,000 K.