A Distinct Nucleosynthetic Heritage for Early Solar System Solids Recorded by Ni Isotope Signatures

Jan Render, Gregory A. Brennecka, Shui Jiong Wang, Laura E. Wasylenki, Thorsten Kleine

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

As the earliest dated solids, calcium-aluminum-rich inclusions (CAIs) provide a unique window into the early solar system. However, for many elements, CAIs have been shown to exhibit a very different nucleosynthetic isotope signature from that of later-formed bulk meteorites. To explore this critical difference between solar system materials, we investigate a broad set of CAI samples for both mass-dependent and non-mass-dependent (nucleosynthetic) isotope variations in the siderophile element nickel (Ni). We find that fine-grained CAIs show little if any mass-dependent Ni isotopic fractionation, whereas coarse-grained inclusions exhibit a broad range of isotopically heavy signatures. Because mass-dependent variations appear to be coupled with nucleosynthetic anomalies in CAIs, a part of this Ni isotope variability could be due to thermal processing that acted on these samples. Nucleosynthetic Ni isotopic signatures show that CAIs share a genetic heritage with carbonaceous meteorites and provide a clear distinction from the isotopic reservoirs occupied by terrestrial Ni and non-carbonaceous meteorites. However, whereas nucleosynthetic Ni isotope heterogeneity in previously investigated bulk meteorites was ascribed to variation in the neutron-poor isotope 58Ni, we here find that CAI signatures require variability in other, more neutron-rich Ni isotopes. Taken in aggregate with previous work, this highlights a change in the nucleosynthetic character from CAIs to later-formed solids that cannot be explained by variable admixture of a single presolar phase or material from a specific supernova shell. Instead, these data reveal the complex evolution of the solar system, including blending and reprocessing of matter from several generations and types of stars.

Original languageEnglish (US)
Article number26
JournalAstrophysical Journal
Volume862
Issue number1
DOIs
StatePublished - Jul 20 2018
Externally publishedYes

Keywords

  • abundances
  • astrochemistry
  • meteorites
  • meteoroids
  • meteors
  • nuclear reactions
  • nucleosynthesis
  • protoplanetary disks
  • supernovae: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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