Caltech/IPAC Lunch Seminar

We are entering an era in which nearby habitable-zone planets around Sun-like and low-mass stars may be directly imaged and spectroscopically characterized, making detailed knowledge of their host stars' high-energy radiation environments essential for interpreting planetary atmospheres and habitability. In this talk, I will highlight my recent work characterizing the X-ray emission of nearby stars relevant to future direct-imaging surveys, of which only ~1/3 have targeted XMM-Newton and/or Chandra X-ray observations available. We uniformly analyzed all these available observations and identified systems with Lx/Lbol ratios similar to the modern and early Sun. By adding analog FGK stars with measured stellar ages, we nearly doubled the size of the stellar sample and examined how coronal temperatures, luminosities, and activity diagnostics evolve with stellar age. These X-ray results are then combined with Hubble FUV and NUV observations and semi-empirical PHOENIX atmosphere models to construct full panchromatic spectral energy distributions for key nearby target stars. These spectra provide the most accurate and detailed models of the high energy radiation environments of these stars to date, with direct implications for atmospheric escape, photochemistry, and the prioritization of these targets for the Habitable Worlds Observatory and Extremely Large Telescopes.