In the last two decades, the field of exoplanets has witnessed a tremendous creative surge. Research in exoplanets now encompasses a wide range of fields ranging from astrophysics to heliophysics and atmospheric science. One of the primary objectives of studying exoplanets is to determine the criteria for habitability, and whether certain exoplanets meet these requirements. The classical definition of the Habitable Zone (HZ) is the region around a star where a planetary surface can support liquid water, but this definition largely ignores the impact of the stellar wind and stellar magnetic activity on the erosion of an exoplanet’s atmosphere. Amongst the many factors that determine habitability, understanding the atmospheric loss is of paramount importance. Most of the recent attention has been centered around the study of exoplanets orbiting M-dwarfs since the latter are highly numerous in our Galaxy (and in the Universe). The study of these exoplanets has also received a major boost from the discovery of Proxima b (Pb) and seven Earth-sized planets in the TRAPPIST-1 system.
In this presentation, I will start with my recent studies on the Martian atmospheric ion loss by using the magnetohydrodynamic (MHD) code as a model validation through data-model comparisons. Then I will discuss the impact of exoplanetary space weather on the climate and habitability, which offers fresh insights concerning the habitability of exoplanets orbiting M-dwarfs. I will focus on the recently discovered Pb and the TRAPPIST-1 system as two examples to demonstrate the importance of the exoplanetary space weather on the atmospheric ion loss.
Finally, I will briefly introduce the high-moment multi-fluid model (conceptually like a fluid version of Particle-in-Cell code, truncated at a certain order of moment) being developed at Princeton University. I will present the global magnetosphere of Ganymede and Mercury as two examples.