Volatile delivery to planets from water-rich planetesimals around low-mass stars

Abstract

Most models of volatile delivery to accreting terrestrial planets assume that the carriers for water are similar in water content to the carbonaceous chondrites in our solar system. Here we consider how the water content of planetesimals may be higher in many planetary systems, as they could lack the short-lived radionuclides that drove water loss in carbonaceous chondrites in our solar system. Using N-body simulations, we explore how planetary accretion would be different if bodies beyond the water line contained a water-mass fraction consistent with chemical equilibrium calculations, and more similar to comets, as opposed to the more traditional water-depleted values. We apply this model to consider planet formation around stars of different masses and identify trends in the properties of habitable zone planets and planetary system architecture that could be tested by ongoing exoplanet census data collection. Comparison of such data with the model-predicted trends will serve to evaluate how well the N-body simulations and the initial conditions used in studies of planetary accretion can be used to understand this stage of planet formation.