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1st of September 2022
Stellar flares from low mass stars using ASKAP and TESS
by Rigney et al.
M dwarfs are core hydrogen-burning stars with masses between 0.07 and 0.6 solar masses. They are the most common type of star in the Milky Way, making up an estimated 70% of the stellar population. Rapid (<10 day) rotation rates and convective cores result in these stars being able to produce energetic flares. It is thought these stellar flares occur via the same magnetic reconnection process as observed in solar flares, and this process also leads to the expulsion of plasma into the stellar atmosphere, known as a stellar coronal mass ejection (CME). While CMEs are a regular occurrence on the Sun, there are relatively few confirmed stellar CMEs. A potential means of observing stellar flares and CMEs is through radio observations.

Rigney et al. conducted two observations with the Australian Square Kilometre Pathfinder Telescope (ASKAP) that were scheduled to overlap observations with the Transiting Exoplanet Survey Satellite (TESS), utilising the wide fields of view of both telescopes to search for multiple M dwarfs. Variable radio emission centered at 888 MHz was detected from four known active M dwarfs. These detections add to the growing number of M dwarfs observed with variable low frequency emission. The image above shows ASKAP Stokes I (total intensity, left) and V (circular polarisation, right) images of one of the four detected M dwarfs. WOH S2 was one of the two sources detected in both Stokes I and Stokes V. The synthesised beam size is illustrated by the black ellipse in the bottom left of each image and is 13.9 x 11.4 arcseconds.

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