Coronal photons, flares, and particles: stellar EUV spectroscopy with ESCAPE

The magnetically heated regions of a cool star’s atmosphere are complex and dynamic, unleashing energy via photons and particles into interplanetary space. In Heliophysics, Earth, and Solar System sciences, extreme-ultraviolet (EUV; 100-912 Å) observations of the Sun are fundamental for understanding solar activity, eruptions, and solar impacts on the Earth and other solar system bodies. Similarly, a complete picture of stellar magnetic activity and its impacts on exoplanet atmospheres requires access to the EUV spectral region. EUV astrophysics observations are challenging due to the interstellar medium, requiring sensitive new instruments such as the Extreme-ultraviolet Stellar Characterization for Atmospheric Physics and Evolution (ESCAPE) mission concept to be submitted to the upcoming NASA Astrophysics Small Explorer call. ESCAPE will provide the first comprehensive study of the stellar EUV and coronal mass ejection (CME) environments of nearby cools stars. ESCAPE simultaneously measures EUV and FUV irradiance, flare rates, and the properties of CMEs via time-resolved 80-1650 Å spectroscopy of over 220 FGKM stars. ESCAPE employs a grazing incidence telescope feeding multiple diffraction gratings and a photon-counting detector. A prototype of the ESCAPE telescope will fly on NASA’s MANTIS cubesat in 2027.