Evaluating the K Dwarf Advantage through the Ultraviolet and X-ray Evolution of K Stars

K dwarfs have recently garnered attention among both stellar and planetary communities as hosts that allow for potentially “super-habitable” planets, due to these stars’ balance between relative population, lifetime, and high-energy radiation in comparison with M- and solar-type stars. The high-energy radiation plays a key role since the UV and X-ray may cause severe photodissociation and ionization of the atmosphere, with the potential for complete erosion. In this talk, I will present my dissertation research regarding the first broad study of the near-UV, far-UV, and X-ray evolution of K stars. I will focus first on the Galaxy Evolution Explorer (GALEX) and Röntgen Satellit (ROSAT) broadband photometric UV and X-ray evolution of K stars ranging in age from 10 Myr to field age (~5 Gyr), and compare this with the age evolution of both early and late M stars. Next, I will discuss our spectroscopic study of a subset of these targets using Hubble Space Telescope’s Cosmic Origins Spectrograph (HST/COS) data and how the line and continua flux for K stars evolves as a function of age and rotation. I will finally revisit the original broadband GALEX photometric study with updated Gaia properties to show that perhaps K stars don’t exhibit quite the advantage that we originally thought: We find that the UV evolution of K stars remains elevated for much longer periods of time than anticipated by the community, jeopardizing the “K dwarf advantage”.