Fourteen new eclipsing white dwarf plus main-sequence binaries from the SDSS and Catalina surveys

TL;DR

This study identifies 17 new eclipsing white dwarf-main sequence binaries from SDSS and Catalina surveys, expanding the known sample and providing insights into their properties and binary evolution.

Contribution

It reports the discovery of 14 new eclipsing WDMS binaries using a targeted colour selection, enhancing the understanding of their characteristics and binary evolution.

Findings

17 eclipsing systems identified, 14 new discoveries

Most systems have earlier spectral types than previous samples

Lower fraction of eclipsing systems suggests faster evolution for early M-type binaries

Abstract

We report on the search for new eclipsing white dwarf plus main-sequence (WDMS) binaries in the light curves of the Catalina surveys. We use a colour selected list of almost 2000 candidate WDMS systems from the Sloan Digital Sky Survey, specifically designed to identify WDMS systems with cool white dwarfs and/or early M type main-sequence stars. We identify a total of 17 eclipsing systems, 14 of which are new discoveries. We also find 3 candidate eclipsing systems, 2 main-sequence eclipsing binaries and 22 non-eclipsing close binaries. Our newly discovered systems generally have optical fluxes dominated by the main-sequence components, which have earlier spectral types than the majority of previously discovered eclipsing systems. We find a large number of ellipsoidally variable binaries with similar periods, near 4 hours, and spectral types M2--3, which are very close to Roche-lobe filling. We also find that the fraction of eclipsing systems is lower than found in previous studies and likely reflects a lower close binary fraction among WDMS binaries with early M-type main-sequence stars due to their enhanced angular momentum loss compared to fully convective late M type stars, hence causing them to become cataclysmic variables quicker and disappear from the WDMS sample. Our systems bring the total number of known detached, eclipsing WDMS binaries to 71.