Finding compact hot subdwarf binaries in the Galactic disc

TL;DR

This paper presents a new survey strategy for discovering compact hot subdwarf binaries in the Galactic disc, including the discovery of two short-period systems and their initial characterization.

Contribution

It introduces a novel observational approach combining photometric surveys and rapid spectroscopic follow-up to identify and analyze short-period hot subdwarf binaries.

Findings

Discovered two short-period hot subdwarf binaries.

Measured orbital periods of 0.11017 and 0.20 days.

Identified a hot subdwarf with a cool M-dwarf and a likely white dwarf companion.

Abstract

We started a new project which aims to find compact hot subdwarf binaries at low Galactic latitudes. Targets are selected from several photometric surveys and a spectroscopic follow-up campaign to find radial velocity variations on timescales as short as tens of minutes has been started. Once radial variations are detected phase-resolved spectroscopy is obtained to measure the radial velocity curve and the mass function of the system. The observing strategy is described and the discovery of two short period hot subdwarf binaries is presented. UVEXJ032855.25+503529.8 contains a hot subdwarf B star (sdB) orbited by a cool M-dwarf in a P=0.11017 days orbit. The lightcurve shows a strong reflection effect but no eclipses are visible. HS 1741+2133 is a short period (P=0.20 days) sdB most likely with a white dwarf (WD) companion.