Detection of an energetic flare from the M5V secondary star in the Polar MQ Dra

TL;DR

This paper reports the detection of a high-energy flare from the secondary star in the magnetic cataclysmic variable MQ Dra, providing insights into stellar activity in such systems.

Contribution

It presents the first observation of an energetic flare from the M5V secondary star in a Polar, expanding understanding of stellar flares in magnetic cataclysmic variables.

Findings

Detected a ~10^35 erg flare from the secondary star in MQ Dra.

Found no evidence of a change in the light curve post-flare.

Discussed the flare rate and magnetic activity of fast-rotating M dwarf stars.

Abstract

MQ Dra is a strongly magnetic Cataclysmic Variable whose white dwarf accretes material from its secondary star through a stellar wind at a low rate. TESS observations were made of MQ Dra in four sectors in Cycle 2 and show a short duration, high energy flare (~10^35 erg) which has a profile characteristic of a flare from the M5V secondary star. This is one of the few occasions where an energetic flare has been seen from a Polar. We find no evidence that the flare caused a change in the light curve following the event and consider whether a coronal mass ejection was associated with the flare. We compare the frequency of energetic flares from the secondary star in MQ Dra with M dwarf stars and discuss the overall flare rate of stars with rotation periods shorter than 0.2 d and how such fast rotators can generate magnetic fields with low differential rotation rates.