Flaring Activity for Low-Mass Stars in the $\beta$ Pictoris Moving Group

TL;DR

This study analyzes flaring activity in young low-mass stars of the $eta$ Pictoris moving group, developing a pipeline to characterize flare properties and comparing flare rates across stellar types to inform stellar and exoplanet evolution.

Contribution

We developed a modular flare extraction pipeline for low-mass stars in TESS data and characterized their flare rates and energies, providing new insights into stellar activity at 24 Myr.

Findings

Flares are more frequent in young low-mass stars than older field stars.

Average flare frequency distribution slope is 1.58 ± 0.23.

Typical stars flare daily with energies of 10^{32} - 10^{33} ergs.

Abstract

Stellar flares from K and M dwarfs release panchromatic radiation characterized by a significantly higher brightness temperature ($\sim$9-20 kK) than the star. The increased frequency of magnetic activity on young low-mass stars results in the energy released during flaring events becoming a notable contributor to the radiation environment. This study focuses on the $\beta$ Pictoris moving group (24 $\pm$ 3 Myr) for the analysis of young, low-mass star flaring rates within the framework of larger flare studies. The calibration of long-term optical flare statistics is crucial to updating flare activity-age relations and the interpretation of exoplanet atmosphere observations. Using the $\beta$ Pictoris moving group, we develop a modular flare extraction pipeline sensitive to low-mass stellar flares in observations from the Transiting Exoplanet Survey Satellite. This pipeline is built to characterize flare properties of these stars such as total energy and cumulative flare rate. Consistent with previous studies, this sample (N=49) shows higher cumulative flare rates than early type and old field stars by at least an order of magnitude. Fitted flare frequency distributions for both early and late type M dwarfs show an average slope of $1.58 \pm 0.23$ with earlier stars flaring with lower or similar rates to late types. A typical member in this sample has daily ($\mathrm{\sim 1 \, d^{-1}}$ ) flares with TESS band energies of $10^{32} - 10^{33}$ ergs. The optical flare rates and energies for this group provide essential context into the co-evolution of host stars and associated planets.