Discovery of the closest hot subdwarf binary with white dwarf companion

TL;DR

This paper reports the discovery of the most compact hot subdwarf binary system with a white dwarf companion, which may evolve into a Type Ia supernova.

Contribution

The discovery of an extremely close, eclipsing hot subdwarf binary with a white dwarf, the closest known, providing insights into binary evolution and supernova progenitors.

Findings

System has a period of approximately 0.04987 days.

The subdwarf will transfer helium-rich material within 50 million years.

Potential to become a Type Ia supernova progenitor.

Abstract

We report the discovery of an extremely close, eclipsing binary system. A white dwarf is orbited by a core He-burning compact hot subdwarf star with a period as short as $\simeq0.04987 {\rm d}$ making this system the most compact hot subdwarf binary discovered so far. The subdwarf will start to transfer helium-rich material on short timescales of less than $50 {\rm Myr}$. The ignition of He-burning at the surface may trigger carbon-burning in the core although the WD is less massive than the Chandrasekhar limit ($>0.74\,M_{\rm \odot}$) making this binary a possible progenitor candidate for a supernova type Ia event.