Bright low mass eclipsing binary candidates observed by STEREO

TL;DR

This study identifies nine bright low-mass eclipsing binary candidates using STEREO data, including a notable system with both components under 0.4 solar radii, advancing the search for small stellar companions.

Contribution

The paper introduces an improved matched filter algorithm for detecting eclipsing binaries in STEREO data and reports new candidate systems, including one confirmed with archival data.

Findings

Nine eclipsing binary candidates identified

One candidate system with both stars <0.4 R_sun

Confirmation of one candidate with archival data

Abstract

Observations from the Heliospheric Imagers (HI-1) on both the STEREO spacecraft have been analysed to search for bright low mass eclipsing binaries (EBs) and potential brown dwarf transits and to determine the radii of the companions. A total of 9 EB candidates have been found, ranging in brightness from V=6.59 mag to V=11.3 mag, where the radius of the companion appears to be less than 0.4 Rsol, with a diverse range of host temperatures, from 4074 K to 6925 K. Both components of one candidate, BD-07 3648, appear to be less than 0.4 Rsol and this represents a particularly interesting system for further study. The shapes of the eclipses in some cases are not clear enough to be certain they are total and the corresponding radii found should therefore be considered as lower limits. The EBs reported in this paper have either been newly found by the present analysis, or previously reported to be eclipsing by our earlier STEREO/HI-1 results. One of the new objects has subsequently been confirmed using archival SuperWASP data. This study was made possible by using an improved matched filter extraction algorithm, which is described in this paper.