Age of Jupiter inferred from the distinct genetics and formation times of meteorites

作者：Kruijer, Thomas S.^*; Burkhardt, Christoph; Budde, Gerrit; Kleine, Thorsten

来源：Proceedings of the National Academy of Sciences, 2017, 114(26): 6712-6716.

DOI：10.1073/pnas.1704461114

• Jupiter
• giant planet formation
• nucleosynthetic isotope anomalies
• Hf-W chronometry
• solar nebula

The age of Jupiter, the largest planet in our Solar System, is still unknown. Gas-giant planet formation likely involved the growth of large solid cores, followed by the accumulation of gas onto these cores. Thus, the gas-giant cores must have formed before dissipation of the solar nebula, which likely occurred within less than 10 My after Solar System formation. Although such rapid accretion of the gas-giant cores has successfully been modeled, until now it has not been possible to date their formation. Here, using molybdenum and tungsten isotope measurements on iron meteorites, we demonstrate that meteorites derive from two genetically distinct nebular reservoirs that coexisted and remained spatially separated between similar to 1 My and similar to 3-4My after Solar System formation. The most plausible mechanism for this efficient separation is the formation of Jupiter, opening a gap in the disk and preventing the exchange of material between the two reservoirs. As such, our results indicate that Jupiter's core grew to similar to 20 Earth masses within <1My, followed by a more protracted growth to similar to 50 Earth masses until at least similar to 3-4 My after Solar System formation. Thus, Jupiter is the oldest planet of the Solar System, and its solid core formed well before the solar nebula gas dissipated, consistent with the core accretion model for giant planet formation.

• 出版日期2017-6-27