Searching for twins of the V1309 Sco progenitor system: a selection of long-period contact binaries

TL;DR

This study searches for contact binary systems similar to the V1309 Sco progenitor to identify potential stellar merger candidates by analyzing period changes and temperature similarities among variable stars.

Contribution

It compiles a selection of long-period contact binaries with similar properties to V1309 Sco and analyzes their eclipse timing variations to identify potential merger candidates.

Findings

Identified 15 contact binaries with similar periods and temperatures to V1309 Sco.

Found 2 systems with decreasing periods among Kepler binaries, potential merger candidates.

Discovered 14 systems with significant period decreases in OGLE data.

Abstract

The only well-studied red nova progenitor (V1309 Sco) was a contact binary with a 1.4-day period. The prospects for searching for similar systems, as well as stellar merger candidates in general, are explored in this work. The photospheric temperatures of 128 variables with periods P = 1.1 - 1.8 d classified as W UMa-type binaries are calculated using their colors listed in the SDSS catalog. A selection of 15 contact binaries with similar temperatures and periods as the V1309 Sco progenitor is thus compiled. The Kepler Eclipsing Binary Catalog is used to analyse systems with eclipse timing variations (ETV) possibly caused by changes of the orbital period. Out of the 31 systems with parabolic ETV curves listed by Conroy et al. (2014, AJ, 147, 45) two could be contact binaries with a decreasing period and, therefore, potential stellar merger candidates. Out of the 569 contact binaries in the OGLE field analysed by Kubiak et al. (2006, AcA, 56, 253) 14 systems have periods longer than 0.8 d and a statistically significant period decrease.