COORDINATED ANALYSIS of TWO GRAPHITE GRAINS from the CO3.0 LAP 031117 METEORITE: FIRST IDENTIFICATION of A CO NOVA GRAPHITE and A PRESOLAR IRON SULFIDE SUBGRAIN

Pierre Haenecour, Christine Floss, Jordi José, Sachiko Amari, Katharina Lodders, Manavi Jadhav, Alian Wang, Frank Gyngard

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

Presolar grains constitute the remnants of stars that existed before the formation of the solar system. In addition to providing direct information on the materials from which the solar system formed, these grains provide groundtruth information for models of stellar evolution and nucleosynthesis. Here we report the in situ identification of two unique presolar graphite grains from the primitive meteorite LaPaz Icefield 031117. Based on these two graphite grains, we estimate a bulk presolar graphite abundance of 5-3+7 ppm in this meteorite. One of the grains (LAP-141) is characterized by an enrichment in 12C and depletions in 33,34S, and contains a small iron sulfide subgrain, representing the first unambiguous identification of presolar iron sulfide. The other grain (LAP- 149) is extremely 13C-rich and 15N-poor, with one of the lowest 12C/13C ratios observed among presolar grains. Comparison of its isotopic compositions with new stellar nucleosynthesis and dust condensation models indicates an origin in the ejecta of a low-mass CO nova. Grain LAP-149 is the first putative nova grain that quantitatively best matches nova model predictions, providing the first strong evidence for graphite condensation in nova ejecta. Our discovery confirms that CO nova graphite and presolar iron sulfide contributed to the original building blocks of the solar system.

Original languageEnglish (US)
Article number88
JournalAstrophysical Journal
Volume825
Issue number2
DOIs
StatePublished - Jul 10 2016
Externally publishedYes

Keywords

  • circumstellar matter
  • meteorites, meteors, meteoroids
  • novae, cataclysmic variables
  • nuclear reactions, nucleosynthesis, abundances
  • stars: AGB and post-AGB
  • supernovae: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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