A Holistic View of Exoplanets, their Environments, and their Potential to Host Life
Arizona State University
Roughly seventy-five billion low-mass stars (a.k.a. M dwarfs) in our galaxy host at least one small planet in the habitable zone (HZ), where surface life might exist. The stellar ultraviolet (UV) radiation from M dwarfs is strong and highly variable, and their planets are exposed to ?superflares? daily in their first ~300 Myr. Knowing the UV environments of planets of all sizes is crucial to understand their atmospheric composition and evolution, and provides the needed context for measured exoplanet spectra at all wavelengths. For HZ terrestrial planets, characterization of the UV provides a key parameter in a planet?s potential to be habitable and helps us to discriminate between biological and abiotic sources for observed biosignatures. Our efforts to study the UV exoplanet environments photometrically and spectroscopically employ past, present and future space telescopes: the Galaxy Evolution Explorer (GALEX), the Hubble Space Telescope, the upcoming SPARCS CubeSat, and a new large mission concept, UV-SCOPE (Ultraviolet Spectroscopic Characterization Of Planets and their Environments). In addition to the study of host star activity, UV-SCOPE will be a dedicated telescope to measure UV transmission spectra of exoplanets. It will probe the conditions and composition of their upper-atmospheres, directly measure exospheric escape, and derive the associated impact of stellar UV radiation upon planets.
|Jeudi, le 18 février 2021
|Université de Montréal