Stellar X-ray Flaring with Mega-MUSCLES

The high-energy emissions of exoplanet hosts stars determine the atmospheric evolutionary history of planets by controlling their mass-loss. The irradiation of high-energy photons ionizes the upper planetary atmosphere, imparts energy, and drives hydrodynamic winds. These processes are further enhanced through intense flaring that can take place throughout the lifetimes of low-mass stars. Recent high-energy surveys, like the Mega-MUSCLES Treasury survey, have measured the X-ray fluxes from a sample of nearby low-mass stars to characterize their X-ray, to ultraviolet spectral energy distributions. These surveys additionally captured numerous X-ray flares spanning 10²⁹ to 10³¹ ergs in energy. We collate these new flaring events with recent high-energy results to examine the impact of flare rates on the high-energy irradiation history of exoplanets, including their overall contribution to the total high-energy flux, and the implications for planetary atmospheric mass-loss.