01/31/2022
By Lynne Schaufenbil
"Returning to the Unobservable Extreme Ultraviolet"
EUV radiation is absorbed at high altitude in a planetary atmosphere, in the exosphere and upper thermosphere, where the gas can be readily heated to escape temperatures. EUV heating and ionization are the dominant atmospheric loss drivers during most of a planet's life. However, there are only a handful of accurately measured EUV stellar fluxes, all dating from Extreme Ultraviolet Explorer (EUVE) observations in the `90s. Consequently, current models of stellar EUV emission are uncertain by more than an order of magnitude and dominate uncertainties in planetary atmospheric loss models. A much more accurate picture of stellar EUV emission is needed if we are to understand planetary atmospheric evolution and which planets might sustain atmospheres over long timescales and potentially be able to sustain life.
Jeremy Drake will describe new space-based efforts to return to the "unobservable extreme ultraviolet, with emphasis on the Normal-incidence Extreme Ultraviolet Photometer (NExtUP), an instrument designed to measure the EUV radiation conditions of exoplanet host stars, and F-M type stars in general. NExtUP may also accomplish a compelling array of secondary science goals, including using line-of-sight absorption measurements to understand the structure of the local interstellar medium, and imaging EUV emission from energetic processes on solar system objects at unprecedented spatial resolution.
If you are interested in participating, please email Lynne_Schaufenbil@uml.edu for the Zoom link.