| M dwarfs, the smallest, faintest, and longest-lived main sequence stars, are the premier exoplanet host star of today due to their abundance of small planets and the relative ease with which we can detect these planets. However, M dwarfs exhibit large levels of magnetic activity, which manifests as X-ray and ultraviolet (UV) emission with frequent flares, and it is uncertain what the planet atmospheres, if present at all, will be like. UV photons control chemistry and mass loss in atmospheres due to the large, wavelength-dependent photoionization cross sections of common atmospheric molecules. Thus, characterizing the UV spectral energy distribution of an exoplanet host star during quiescence and flares is critical for evaluating the origin of any molecules detected in a planet atmosphere. H I Lyman alpha (1215.67 Å) dominates the far-UV spectrum of cool dwarf stars, especially M dwarfs, but strong absorption from neutral hydrogen in the interstellar medium and Earth's Lyman alpha airglow makes direct observations of the intrinsic Lyman alpha emission from even the closest stars challenging. I describe the techniques used to recover this important emission line from Hubble Space Telescope STIS and COS spectroscopy, including as part of the MUSCLES (Measurements of the Ultraviolet Spectral Characteristics of Low-mass Exoplanetary Systems) and FUMES (Far Ultraviolet M-dwarf Evolution Survey) surveys, and how the strength of Lyman alpha and other UV emission lines evolve with stellar age and activity. I will also present some preliminary results from an ongoing multiwavelength flare survey of young and old M dwarfs primarily with TESS and Swift and supporting observations with SNIFS, Hubble, Las Cumbres Observatory, and the VLA. |