Hints for neutrino-process boron in presolar silicon carbide grains from supernovae

Wataru Fujiya, Peter Hoppe, Ulrich Ott

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16 Citations (Scopus)

Abstract

We have studied more than 1000 presolar silicon carbide (SiC) grains from the Murchison CM2 chondrite for C- and Si-isotopic compositions. Twelve SiC X grains, characterized by strong enrichments in 28Si and believed to originate from Type II Supernovae (SNeII), were also measured for Li- and B-isotopic compositions. None of these grains show resolvable isotope anomalies in Li or B. For the seven X grains without Li and B contributions from nearby or attached SiC grains of distinct origins we find on average 7Li/ 6Li = 11.83 0.29 (solar system: 12.06) and 11B/ 10B = 4.68 0.31 (solar system: 4.03). The average 7Li/6Li is compatible with the solar system ratio and the lithium in the X grains is likely largely dominated by contaminating Li of laboratory or meteoritic origin. Also, most of the boron in X grains appears to be contamination but the small 11B excess of 16%, significant at the 2σ level, can be considered a hint for the presence of boron produced by the neutrino process in the parent SNeII. Despite this finding, a quantitative comparison of the B isotope and abundance data of X grains with model predictions reveals deficiencies in our current understanding of the details of B production in SNeII as well as on B chemistry and condensation in SNII ejecta.

Original languageEnglish
Article numberL7
JournalAstrophysical Journal Letters
Volume730
Issue number1 PART II
DOIs
Publication statusPublished - Mar 20 2011

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Keywords

  • circumstellar matter
  • nuclear reactions: nucleosynthesis: abundances
  • supernovae: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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