RX J0648.0--4418: the fastest-spinning white dwarf

TL;DR

This paper discusses RX J0648.0-4418, a binary system with an exceptionally fast-spinning white dwarf, exploring its unique properties and potential evolutionary outcomes such as supernovae or millisecond pulsars.

Contribution

It provides the first detailed characterization of RX J0648.0-4418's white dwarf, highlighting its rapid spin and mass, and discusses its possible future as a supernova progenitor or millisecond pulsar.

Findings

White dwarf mass measured at 1.28 solar masses.

White dwarf spin period is 13.2 seconds, faster than similar systems.

Potential evolution into a Type Ia supernova or millisecond pulsar.

Abstract

RX J0648.0-4418 is a post common-envelope X-ray binary composed of a hot subdwarf and one of the most massive white dwarfs with a dynamical mass measurement (1.28+/-0.05 M_sun). This white dwarf, with a spin period of 13.2 s, rotates more than twice faster than the white dwarf in the cataclysmic variable AE Aqr. The current properties of these two binaries, as well as their future evolution, are quite different, despite both contain a fast-spinning white dwarf. RX J0648.0-4418 could be the progenitor of either a Type Ia supernova or of a non-recycled millisecond pulsars.