Geosciences Dept. Seminar: On the abundance of biotic exoplanets and life on planets of Red Dwarfs

Abstract:

The Kepler mission has shown that Earthlike planets within the Habitable Zone of their host stars are common. I derive an expression for the abundance of life boring (biotic) extra-solar-system planets (exoplanets) in terms of the of the (yet unknown) probability for the evolution of biotic life. This "biotic probability" may be estimated by future missions and observations, e.g. spectral analyses of the atmospheres of exoplanets, looking for biomarkers. We show that if the biotic probability is in the range 0.001-1, a biotic planet may be expected within 10 -- 100 light years from Earth. 

Of particular interest in the search for exolife are planets orbiting Red Dwarf (RD) stars, the most frequent stellar type. Previous researches suggested that conditions on planets near RDs would be inimical to life, e.g. as the Habitable Zone would be small enough to make habitable planets tidally locked. Recent calculations show that this and other  properties of RDs, presumed hostile for the evolution of life,  are less severe than originally estimated. I conclude that RD planets could be hospitable for the evolution of life as we know it, not less than planets of solar-type stars. The huge number of  and their long lifetimes make finding life on RD planets more likely than on planets of solar-type stars.

Seminar Organizer: Prof. Ravit Heled