Which Terrestrial Exoplanets Deserve More Scrutiny for Atmosphere Viability?
Abstract
We introduce a practical and physically intuitive method to assess whether a given exoplanet is a viable candidate for the existence of an atmosphere thanks to an efficient magnetospheric shielding from intense space weather activity originating from its host star. Our proposed mASC (magnetic Atmosphere Sustainability Constraint) relies on a best-case scenario for the dynamo-generated planetary magnetic field and subsequent magnetic pressure, and a worst-case scenario for the magnetic pressure of stellar CMEs. It provides a dimensionless ratio R whose excursion from unity implies accordingly an atmosphere likely (R < 1) or an atmosphere unlikely (R > 1) scenario. In this work, we implement our mASC on six famous exoplanets whose discovery was greeted with praise and hopes of habitability. These are Kepler-438b, Proxima-Centauri b, and Trappist-1d, -1e, -1f, -1g. The results show that for none of them the existence of an atmosphere is likely while our findings are robust for five out of six cases. We conclude that the mASC ratio could help set observing priorities and suggest which exoplanets deserve further scrutiny, possibly toward the ultimate search of potential biosignatures, among other objectives.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.U44B..05S