A method to assess planetary habitability based on the effects of CME magnetic fields on planetary magnetospheres
Abstract
In this work, we propose a methodology to assess planetary surface habitability for any newly discovered exoplanet lying in the habitable zone of a low mass, superflare, main-sequence star. While habitability is usually a function of multiple parameters (i.e. the size of the planet, the composition of its atmosphere, the existence of liquid water, orbital or rotational dynamics), the presented method primarily focuses on stellar activity and its effects on potentially existing planetary magnetospheres stemming from dynamo-generated magnetic fields. The area our method applies to, is split in two regimes depending on whether the exoplanet of interest is tidally locked or tidally unlocked to its mother star. In the former case, a ratio between a conditional (Beq) and a best-case equatorial planetary magnetic field (Bstev), is calculated. A smaller-than-unity value of that ratio favors the formation of a stable atmosphere adequate to host surface, atmosphere-dependent habitability. In the latter case (tidally unlocked regime), a ratio between a conditional (Beq) and the terrestrial magnetic field (Bearth) is estimated, which indirectly implies how easy or hard it is for an exoplanet to sustain an atmosphere. For a ratio's value lower than unity, there is hope for surface habitability since its magnetic field is assumed equal to, or larger than, the terrestrial one. On the other hand, a value higher than one casts doubts on surface habitability, because even a strong, terrestrial magnetic field is not sufficient to secure an atmosphere for the exoplanet. Both ratios concerning the two different spatial regimes of our method's application are based on the observed mother star's activity and are calculated on the critical magnetopause distance of two planetary radii, below which atmospheric erosion phenomena are assumed to start taking place.
- Publication:
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Solar Heliospheric and INterplanetary Environment (SHINE 2018)
- Pub Date:
- July 2018
- Bibcode:
- 2018shin.confE.216S