Isotopic variation of non-carbonaceous meteorites caused by dust leakage across the Jovian gap in the solar nebula

Abstract

Abstract High-precision isotopic measurements of meteorites revealed that they are classified into non-carbonaceous (NC) and carbonaceous (CC) meteorites. One plausible scenario for achieving this grouping is the early formation of Jupiter, because massive planets can create gaps that suppress the mixing of dust across the gap in protoplanetary disks. However, the efficiency of this suppression by the gaps depends on dust size and the strength of turbulent diffusion, allowing some fraction of the dust particles to leak across the Jovian gap. In this study, we investigate how isotopic ratios of NC and CC meteorites are varied by the dust leaking across the Jovian gap in the solar nebula. To do this, we constructed a model to simulate the evolution of the dust size distribution and the $^{54}$Cr-isotopic anomaly $\varepsilon ^{54}$Cr in isotopically heterogeneous disks with Jupiter. Assuming that the parent bodies of NC and CC meteorites are formed in two dust-concentrated locations inside and outside Jupiter’s orbit, referred to as the NC reservoir and the CC reservoir, we derive the temporal variation of $\varepsilon ^{54}$Cr at the NC and CC reservoirs. Our results indicate that substantial contamination from CC materials occurs at the NC reservoir in the fiducial run. Nevertheless, the values of $\varepsilon ^{54}$Cr at the NC reservoir and the CC reservoir in the run are still consistent with those of NC and CC meteorites formed around $2\:$Myr after the formation of calcium–aluminum-rich inclusions (Sugiura & Fujiya 2014, Meteorit. Planet. Sci., 49, 772). Moreover, this dust leakage causes a positive correlation between the $\varepsilon ^{54}$Cr value of NC meteorites and the accretion ages of their parent bodies.