Far Ultraviolet M-dwarf Evolution Survey: Magnetic Heating and the Transition Region

M-dwarf stars are prime targets for exoplanet searches because of their close proximity and favorable properties for both planet detection and characterization, with current searches around these targets having already discovered several Earth-sized planets within their star’s habitable zones, and many more to come with missions like the Transiting Exoplanet Survey Satellite. However, the atmospheric characterization and potential habitability of these exoplanetary systems depends critically on the high-energy stellar radiation environment from X-rays to NUV that drives atmospheric mass-loss and photochemistry. I will present recent results from the Far Ultraviolet M-dwarf Evolution Survey (FUMES), using HST-STIS to measure the FUV transition region emission features of young active M-dwarfs, as proxies for the entire high-energy spectrum. At young ages and fast rotation rates these high-energy emissions can be orders of magnitude greater than that of the older inactive M-dwarfs, posing a significant threat to young planetary atmospheres. These new measurements further provide a way to measure the evolution of the high-energy spectrum and understand magnetic heating processes throughout the upper atmosphere from the chromosphere, transition region and into the corona.

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