Close binary progenitors and ejected companions of thermonuclear supernovae

TL;DR

This paper identifies and analyzes close binary systems involving hot subdwarf stars and white dwarfs, which are potential progenitors of type Ia supernovae, and reports new candidate systems with high velocities and compactness.

Contribution

It reports the discovery of new candidate progenitor systems and high-velocity stars, expanding the known population of potential thermonuclear supernovae progenitors.

Findings

72 sdO/B candidates with high velocities, 12 possibly unbound

Discovered the second-most compact sdB+WD binary

Low-mass WD companion unlikely to produce SN Ia

Abstract

Hot subdwarf stars (sdO/Bs) are evolved core helium-burning stars with very thin hydrogen envelopes, which can be formed by common envelope ejection. Close sdB binaries with massive white dwarf (WD) companions are potential progenitors of thermonuclear supernovae type Ia (SN~Ia). We discovered such a progenitor candidate as well as a candidate for a surviving companion star, which escapes from the Galaxy. More candidates for both types of objects have been found by crossmatching known sdB stars with proper motion and light curve catalogues. We found 72 sdO/B candidates with high Galactic restframe velocities, 12 of them might be unbound to our Galaxy. Furthermore, we discovered the second-most compact sdB+WD binary known. However, due to the low mass of the WD companion, it is unlikely to be a SN\,Ia progenitor.