Searching for the Origin of Flares in M dwarfs

by Lauren Doyle

Hosted by Armagh Observatory on June 14, 2018


We present an overview of K2 short cadence observations for 32 M dwarfs which have spectral types between M0-L1. All of the stars in our sample showed flares with the most energetic reaching 3x10^34 ergs. As previous studies have found, we find rapidly rotating stars tend to show more flares, with evidence for a decline in activity in stars with rotation periods longer than approximately 10 days. We determined the rotational phase of each flare and performed a simple statistical test on our sample to determine whether the phase distribution of the flares is random or if there is a preference for phase. We find none show a preference for the rotational phase of the flares. If the analogy between the physics of solar and stellar flares holds and these events occur from active regions which typically host spots, then you would expect to see more flares during the rotation minimum where the starspot is most visible. However, this is not the case with our sample and in fact all of our stars show flares at all rotational phases, suggesting these flares are not all originating from one dominant starspot on the surface of the stars. We outline three scenarios which could explain the lack of a correlation between the number of flares and the stellar rotation phase.


Seminar video