Discovery of a magnetic white dwarf with unusual short-period variability

TL;DR

This paper reports the discovery of a magnetic white dwarf exhibiting unique short-period variability, likely caused by magnetic spots or an unseen ultracool companion, revealing new insights into white dwarf behavior.

Contribution

It introduces a previously unknown variability pattern in magnetic white dwarfs, suggesting magnetic spots or an ultracool companion as possible causes.

Findings

Periodic variability with P=110 min observed

Color-dependent amplitude and phase shift detected

Proposes magnetic spots or ultracool companion as cause

Abstract

We report the discovery of a magnetic white dwarf which shows periodic variability with P=110 min, color-dependent amplitudes and a transient phase shift in the blue compared to the red lightcurve - a previously unknown type of variability for this type of object. We attribute the variations either to a close ultracool (thus far undetected) companion or, more likely, to magnetic spots with unusual temperature structure.