3:30 PM - 3:45 PM
[MIS18-13] Evolution of D/H ratios on rocky proto-planets growing in the solar nebula
Keywords:proto-planets, D/H ratio
We analyze 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 (Saito & Kuramoto, 2018). As a result, we found that when the volatile fraction in the planetary building blocks is lower than about 1 wt%, the solar nebula component layer and the degassed component layer would be mixed due to the opaque and convective solar nebula layer. This tendency becomes strong when the planetary mass is large.
Our preliminary analysis suggests that the mean D/H ratio of planetary atmosphere would become close to that of the solar nebula due to the convective mixing on a rocky proto planet larger than Mars. In addition, the surface temperature would increase up to the melting temperature of the rock. Hence, the D/H ratio of the interior of such a proto-planet would get close to that of the solar nebula. This result may account for the low D/H ratio of the Earth's volcanic rock likely originated from deep mantle (Hallis et al., 2015).