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Title: Carbon-rich presolar grains from massive stars. Subsolar 12 C/ 13 C and 14 N/ 15 N ratios and the mystery of 15 N

We compared carbon-rich grains with isotopic anomalies to the Sun are found in primitive meteorites. They were made by stars, and carry the original stellar nucleosynthesis signature. Silicon carbide grains of Type X and C and low-density (LD) graphites condensed in the ejecta of core-collapse supernovae. Furthermore, we present a new set of models for the explosive He shell and compare them with the grains showing 12C/ 13C and 14N/ 15N ratios lower than solar. In the stellar progenitor H was ingested into the He shell and not fully destroyed before the explosion. All of the explosion energies and H concentrations are considered. If the supernova shock hits the He-shell region with some H still present, the models can reproduce the C and N isotopic signatures in C-rich grains. Hot-CNO cycle isotopic signatures are obtained, including a large production of 13C and 15N. The short-lived radionuclides 22Na and 26Al are increased by orders of magnitude. The production of radiogenic 22Ne from the decay of 22Na in the He shell might solve the puzzle of the Ne-E(L) component in LD graphite grains. This scenario is attractive for the SiC grains of type AB with 14N/ 15N ratios lower than solar, andmore » provides an alternative solution for SiC grains originally classified as nova grains. Finally, this process may contribute to the production of 14N and 15N in the Galaxy, helping to produce the 14N/ 15N ratio in the solar system.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9]
  1. Hungarian Academy of Sciences, Budapest (Hungary). Research Center for Astronomy and Earth Sciences; Univ. of Basel (Switzerland). Dept. of Physics
  2. Washington Univ., St. Louis, MO (United States). Lab. for Space Sciences and Physics Dept.
  3. Max Planck Inst. for Chemistry, Mainz (Germany)
  4. Univ. of Hull (United Kingdom). E.A Milne Center for Astrophysics
  5. Chicago Center for Cosmochemistry, Chicago, IL (United States). Dept. of Geophysical Sciences
  6. Univ. of Victoria, BC (Canada). Dept. of Physics and Astronomy; Joint Inst. for Nuclear Astrophysics (JINA), Notre Dame, IN (United States)
  7. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  8. Keele Univ. (United Kingdom); Univ. of Tokyo (Japan). Inst. for the Physics and Mathematics of the Universe (WPI)
  9. Joint Inst. for Nuclear Astrophysics (JINA), Notre Dame, IN (United States); Arizona State Univ., Tempe, AZ (United States)
Publication Date:
Report Number(s):
LA-UR-15-21497
Journal ID: ISSN 2041-8213
Grant/Contract Number:
AC52-06NA25396; PHY 02-16783; PHY- 09-22648; PHY-1430152; EU MIRG-CT-2006-046520; EU-fP7-ERC-2012-St; NNX11AH14G; NNX09AG39G
Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal. Letters
Additional Journal Information:
Journal Volume: 808; Journal Issue: 2; Journal ID: ISSN 2041-8213
Publisher:
Institute of Physics (IOP)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; nuclear reactions; nucleosynthesis; abundances-stars: abundances; stars: evolution; stars: interiors; supernovae: general
OSTI Identifier:
1329581