^1,2Jan L. Hellmann,^1,3Jonas M. Schneider,^1,3Elias Wölfer,³Joanna Drążkowska,¹Christian A. Jansen,^1,3Timo Hopp,^1,3Christoph Burkhardt,^1,3Thorsten Kleine
The Astrophysical Journal 946, L34 Open Access Link to Article [DOI 10.3847/2041-8213/acc102]
¹Institut für Planetologie, University of Münster, Wilhelm-Klemm-Str. 10, D-48149 Münster, Germany;
²Department of Geology, University of Maryland, 8000 Regents Drive, College Park, MD 20742, USA
³Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, D-37077 Göttingen, Germany

Carbonaceous chondrites are some of the most primitive meteorites and derive from planetesimals that formed a few million years after the beginning of the solar system. Here, using new and previously published Cr, Ti, and Te isotopic data, we show that carbonaceous chondrites exhibit correlated isotopic variations that can be accounted for by mixing among three major constituents having distinct isotopic compositions, namely refractory inclusions, chondrules, and CI chondrite-like matrix. The abundances of refractory inclusions and chondrules are coupled and systematically decrease with increasing amount of matrix. We propose that these correlated abundance variations reflect trapping of chondrule precursors, including refractory inclusions, in a pressure maximum in the disk, which is likely related to the water ice line and the ultimate formation location of Jupiter. The variable abundance of refractory inclusions/chondrules relative to matrix is the result of their distinct aerodynamical properties resulting in differential delivery rates and their preferential incorporation into chondrite parent bodies during the streaming instability, consistent with the early formation of matrix-poor and the later accretion of matrix-rich carbonaceous chondrites. Our results suggest that chondrules formed locally from isotopically heterogeneous dust aggregates, which themselves derive from a wide area of the disk, implying that dust enrichment in a pressure trap was an important step to facilitate the accretion of carbonaceous chondrite parent bodies or, more generally, planetesimals in the outer solar system.

¹Ryan C. Ogliore
Geochemistry (Chemie der Erde) (in Press) Link to Article [https://doi.org/10.1016/j.chemer.2023.126046]
¹McDonnell Center for the Space Sciences, Washington University in St. Louis, 1 Brookings Dr., St. Louis 63130, MO, USA
Copyright Elsevier

NASA’s Stardust mission returned rocky material from the coma of comet 81P/Wild 2 (pronounced “Vilt 2”) to Earth for laboratory study on January 15, 2006. Comet Wild 2 contains volatile ices and likely accreted beyond the orbit of Neptune. It was expected that the Wild 2 samples would contain abundant primordial molecular cloud material—interstellar and circumstellar grains. Instead, the interstellar component of Wild 2 was found to be very minor, and nearly all of the returned particles formed in broad and diverse regions of the solar nebula. While some characteristics of the Wild 2 material are similar to primitive chondrites, its compositional diversity testifies to a very different origin and evolution history than asteroids. Comet Wild 2 does not exist on a continuum with known asteroids. Collisional debris from asteroids is mostly absent in Wild 2, and it likely accreted dust from the outer and inner Solar System (across the putative gap created by a forming Jupiter) before dispersal of the solar nebula. Comets are a diverse set of bodies, and Wild 2 may represent a type of comet that accreted a high fraction of dust processed in the young Solar System.