The view from K2: Questioning the traditional view of flaring on early dM stars

TL;DR

This study analyzes K2 data of two early M dwarf stars, revealing flare activity similar to later types but less frequent, and discusses data analysis methods and biases in measuring stellar activity.

Contribution

The paper introduces a moving aperture technique for analyzing K2 data, improving flare detection accuracy on M dwarf stars.

Findings

Flares observed are as energetic as those from later M dwarfs.

Flare frequency is about 8 times lower than in more active M0--M5 stars.

Moving aperture reduces non-astrophysical features in data analysis.

Abstract

We use K2 short cadence data obtained over a duration of 50 days during Campaign 0 to observe two M1V dwarf stars, TYC 1330-879-1 and RXJ 0626+2349. We provide an overview of our data analysis, in particular, making a comparison between using a fixed set of pixels and an aperture which follows the position of the source. We find that this moving aperture approach can give fewer non-astrophysical features compared to a fixed aperture. Both sources shows flares as energetic as observed from several M4V stars using both Kepler and ground based telescopes. We find that the flare energy distribution of the sources shown here are very similar to the less active M3-M5 stars but are ~8 times less likely to produce a flare of a comparable energy to the more active M0--M5 stars. We discuss the biases and sources of systematic errors when comparing the activity of stars derived from different instruments. We conclude that K2 observations will provide an excellent opportunity to perform a census of flare activity across the full range of M dwarf spectral class and hence the physical mechanisms which power them.