Kepler Flares IV: A Comprehensive Analysis of the Activity of the dM4e Star GJ 1243

TL;DR

This study provides a detailed analysis of flare activity on the star GJ 1243 using Kepler data and ground-based spectroscopy, revealing variability in flare energy distribution and extending spectral analysis to lower energies.

Contribution

It offers the first simultaneous spectroscopic and photometric analysis of low-energy flares on an M dwarf, and develops conversions from Kepler data to traditional U and B bands.

Findings

Flare energy distribution exponent varies over time.

Deviation from a single power law at high energies.

Ground-based spectra of low-energy flares extend RHD model constraints.

Abstract

We present a comprehensive study of the active dM4e star GJ 1243. We use previous observations and ground-based echelle spectroscopy to determine that GJ 1243 is a member of the Argus association of field stars, suggesting it is $\sim 30-50$ Myr old. We analyze eleven months of 1-minute cadence data from Kepler, presenting Kepler flare frequency distributions, as well as determining correlations between flare energy, amplitude, duration, and decay time. We find that the exponent $\alpha$ of the power-law flare energy distribution varies in time, primarily due to completeness of sample and the low frequency of high-energy flares. We also find a deviation from a single power law at high energy. We use ground-based spectroscopic observations simultaneous with the Kepler data to provide simultaneous photometric and spectroscopic analysis of three low-energy flares, the lowest-energy dMe flares with detailed spectral analysis to date on any star. The spectroscopic data from these flares extend constraints for radiative hydrodynamic (RHD) flare models to a lower energy regime than has previously been studied. We use this simultaneous spectroscopy and Kepler photometry to develop approximate conversions from the \textit{Kepler} bandpass to the traditional $U$ and $B$ bands. This conversion will be a critical factor in comparing any Kepler flare analyses to the canon of previous ground-based flare studies.