In this talk, I will discuss some of the constraints on planetary habitability that are regulated by the host star. The first factor is the role of the stellar wind and stellar flares in driving atmospheric erosion. It will be shown that low-mass M-dwarfs are particularly susceptible to this process, and may lose their atmospheres over sub-Gyr timescales. The second part focuses on the putative role of ultraviolet (UV) radiation in determining the timescales for the origin of simple and complex life, and the ensuing implications for Earth-sized planets. Lastly, I will outline the opposing effects of stellar flares: on the one hand, they may help facilitate the origin of life, but on the other hand large flares can prove to be detrimental to complex life. Collectively, these factors might indicate that planets orbiting M-dwarfs are not conducive to the sustenance of long-term complex biospheres. However, in light of the many unknown factors, these statements must be taken with due caution.
How habitable are "habitable" planets?
Manasvi Lingam (ITC)
Thursday, 4 January 2018