ES-02-0021

Protosolar disk shadow may explain the hyper volatile enrichment in Jupiter's atmosphere

Kazumasa Ohno

Atmospheric compositions offers valuable clues to planet formation and evolution. Jupiter has been the most well studied giant planets in terms of atmospheres. One of the long standing puzzle regarding the Jovian atmosphere is the super-solar abundances of nitrogen and noble gasses. This hyper volatile enrichment leads recent studies to suggest that proto-Jupiter might form at >30 AU where N2 and noble gasses can freeze; however, the Jupiter formation at such far distance is challenging according to the current planet formation theory. Here, we propose an alternative novel idea: a disk substructure casts a shadow and makes the Jupiter's orbit much colder than the previous thought. We consider the dust pileup at H2O snowline caused by the fragmentation of rocky dust particles. Using radiative transfer calculation, we demonstrate that the dust pileup drastically cools the orbital distance of 3--7 AU through shadow formation. We then perform condensation calculations and find that N2 and noble gasses can freeze at the current Jupiter's orbit 5 AU if sufficient amount of dust is accumulated inside H2O snowline. Thus, Jupiter could acquire abundant hyper volatiles as condensed ices even if Jupiter was formed near the current orbit. A general implication of our study is that the disk substructures play a vital role to determine the disk thermal structure and resulting planetary compositions, which should be further studied in the era of JWST.