[P-CG20] Origin and evolution of materials in space

[PCG20-P01] A theoretical study on oxygen isotope exchange between molten silicate and water vaper with large relative velocity

*Sota Arakawa¹, Daiki Yamamoto², Takayuki Ushikubo³, Hiroaki Kaneko⁴, Hidekazu Tanaka⁵, Shigenobu Hirose¹, Taishi Nakamoto⁴ (1.Yokohama Institute for Earth Sciences, Japan Agency for Marine-Earth Science and Technology, 2.Kyushu University, 3.Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, 4.Tokyo Institute of Technology, 5.Tohoku University)

Keywords:Oxygen isotope exchange, Chondrule, Molten silicate, Protoplanetary disk

Oxygen isotope compositions of chondrules reflect the environment of chondrule formation and its spatial and temporal variations. Here we present a theoretical model of oxygen isotope exchange reaction between molten silicate spherules and ambient water vapor with finite relative velocity, and we also discuss the plausible condition for chondrule formation from the point of view of oxygen isotope compositions. We found a new phenomenon, that is, mass-dependent fractionation caused by isotope exchange with ambient vapor moving with nonzero relative velocity. Our findings indicate that the relative velocity between chondrules and ambient vapor would be lower than several 100 m/s when chondrules crystallized.