White-light flares on cool stars in the Kepler Quarter 1 Data

TL;DR

This study analyzes white-light flares on about 23,000 cool stars from Kepler data, revealing differences in flare frequency, duration, and energy between M and K dwarfs, and their relation to stellar variability.

Contribution

It provides the first large-scale statistical analysis of white-light flares on a broad sample of cool stars from Kepler data, including flare energies, rates, and their relation to stellar variability.

Findings

M dwarfs flare more frequently but for shorter durations than K dwarfs.

M dwarfs emit more energy relative to their quiescent luminosity during flares.

Stars with higher quiescent variability tend to emit more energy during flares.

Abstract

We present the results of a search for white light flares on the ~23,000 cool dwarfs in the Kepler Quarter 1 long cadence data. We have identified 373 flaring stars, some of which flare multiple times during the observation period. We calculate relative flare energies, flare rates and durations, and compare these with the quiescent photometric variability of our sample. We find that M dwarfs tend to flare more frequently but for shorter durations than K dwarfs, and that they emit more energy relative to their quiescent luminosity in a given flare than K dwarfs. Stars that are more photometrically variable in quiescence tend to emit relatively more energy during flares, but variability is only weakly correlated with flare frequency. We estimate distances for our sample of flare stars and find that the flaring fraction agrees well with other observations of flare statistics for stars within 300 pc above the Galactic Plane. These observations provide a more rounded view of stellar flares by sampling stars that have not been pre-selected by their activity, and are informative for understanding the influence of these flares on planetary habitability.