Kepler Flares II: The Temporal Morphology of White-Light Flares on GJ 1243

TL;DR

This study analyzes over 6100 white-light flares on the M dwarf GJ 1243 using Kepler data, revealing detailed flare morphology, decay phases, and complex event structures, advancing understanding of stellar flare physics.

Contribution

We compiled the largest flare sample for a single M dwarf, developed automated detection tools, and created a median flare template with insights into flare decay phases.

Findings

Two exponential decay phases identified in flare light curves.

Over 80% of long-duration flares are complex and multi-peaked.

Flare durations follow a broken power law distribution.

Abstract

We present the largest sample of flares ever compiled for a single M dwarf, the active M4 star GJ 1243. Over 6100 individual flare events, with energies ranging from $10^{29}$ to $10^{33}$ erg, are found in 11 months of 1-minute cadence data from Kepler. This sample is unique for its completeness and dynamic range. We have developed automated tools for finding flares in short-cadence Kepler light curves, and performed extensive validation and classification of the sample by eye. From this pristine sample of flares we generate a median flare template. This template shows that two exponential cooling phases are present during the white-light flare decay, providing fundamental constraints for models of flare physics. The template is also used as a basis function to decompose complex multi-peaked flares, allowing us to study the energy distribution of these events. Only a small number of flare events are not well fit by our template. We find that complex, multi-peaked flares occur in over 80% of flares with a duration of 50 minutes or greater. The underlying distribution of flare durations for events 10 minutes and longer appears to follow a broken power law. Our results support the idea that sympathetic flaring may be responsible for some complex flare events.