COSMOCHEMISTRY

Meteorites formed in two reservoirs

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Science  14 Jul 2017:
Vol. 357, Issue 6347, pp. 160
DOI: 10.1126/science.357.6347.160-a

Jupiter's orbit marks the boundary between the formation reservoirs of two distinct meteorite types.

CREDIT: NASA

Meteorites are rocky debris left over from the formation of the solar system, which later fall to Earth. Kruijer et al. measured tungsten and molybdenum isotope ratios for a variety of iron meteorite groups and showed that they separate into two sequences—just like stony meteorites are already known to do. Because iron meteorites require parent bodies that grew massive enough to form metal cores, this dichotomy implies two separate regions in the early solar system where planetesimals formed. The authors speculate that the two reservoirs were respectively within and outside the orbit of Jupiter. If that is correct, the giant planet must have formed rapidly, before the meteorite parent bodies did.

Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1704461114 (2017).

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