[PPS09-12] D/H ratio and water partitioning into the protoplanetary interior
Keywords:D/H ratio, proto-planet, proto-atmosphere, proto-Earth
Our resent paper, Saito & Kuramoto (2020), focused on the rapid planetary accretion suggested by Hf-W chronology studies and analyzed the thermal structure of a hybrid-type proto-atmosphere where the solar nebula component dominates the upper layer, and the degassed component dominates the lower layer, by developing a 1D radiative-equilibrium model. Our calculation implies Mars-sized proto-planets keep a hybrid-type proto-atmosphere and the D/H ratio of the lower atmosphere resembles that of the building blocks. Conversely, when the mass is larger than Mars, the compositional stratification is collapsed by convective mixing of the solar nebula component with the degassed component, and the D/H ratio approaches that of the solar nebula. The D/H ratio of the mixed proto-atmosphere readily reaches the value of primordial terrestrial water when planetary mass grows up to two times the Mars mass.
In this presentation, we will discuss the conditions under which protoplanets with low D/H ratios are formed such as the atmospheric pressure, composition, and the amount of water and other volatiles partitioned into the planetary interior.