An unusual white dwarf star may be a surviving remnant of a subluminous Type Ia supernova

TL;DR

This paper reports the discovery of a high-velocity white dwarf with a peculiar atmosphere, likely a remnant of a subluminous Type Ia supernova, supporting models of single-degenerate supernova progenitors.

Contribution

It provides observational evidence linking a peculiar white dwarf to a past subluminous Type Ia supernova event, supporting specific explosion models.

Findings

Discovered a high-velocity, low-mass white dwarf (LP 40-365).

White dwarf's atmosphere is dominated by intermediate-mass elements.

Evidence suggests the white dwarf is a supernova remnant.

Abstract

Subluminous Type Ia supernovae, such as the Type Iax class prototype SN 2002cx, are described by a variety of models such as the failed detonation and partial deflagration of an accreting carbon-oxygen white dwarf star, or the explosion of an accreting, hybrid carbon-oxygen-neon core. These models predict that bound remnants survive such events with, according to some simulations, a high kick velocity. We report the discovery of a high proper motion, low-mass white dwarf (LP 40-365) that travels at a velocity greater than the Galactic escape velocity and whose peculiar atmosphere is dominated by intermediate-mass elements. Strong evidence indicates that this partially burnt remnant was ejected following a subluminous Type Ia supernova event. This supports the viability of single-degenerate supernova progenitors.