EVIDENCE FOR RADIOGENIC SULFUR-32 IN TYPE AB PRESOLAR SILICON CARBIDE GRAINS?
Abstract
We report C, Si, and S isotope measurements on 34 presolar silicon carbide grains of Type AB, characterized by {sup 12}C/{sup 13}C < 10. Nitrogen, Mg-Al-, and Ca-Ti-isotopic compositions were measured on a subset of these grains. Three grains show large {sup 32}S excesses, a signature that has been previously observed for grains from supernovae (SNe). Enrichments in {sup 32}S may be due to contributions from the Si/S zone and the result of S molecule chemistry in still unmixed SN ejecta or due to incorporation of radioactive {sup 32}Si from C-rich explosive He shell ejecta. However, a SN origin remains unlikely for the three AB grains considered here, because of missing evidence for {sup 44}Ti, relatively low {sup 26}Al/{sup 27}Al ratios (a few times 10{sup –3}), and radiogenic {sup 32}S along with low {sup 12}C/{sup 13}C ratios. Instead, we show that born-again asymptotic giant branch (AGB) stars that have undergone a very-late thermal pulse (VLTP), known to have low {sup 12}C/{sup 13}C ratios and enhanced abundances of the light s-process elements, can produce {sup 32}Si, which makes such stars attractive sources for AB grains with {sup 32}S excesses. This lends support to the proposal that at least some AB grainsmore »
- Authors:
-
- Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, D-55128 Mainz (Germany)
- Laboratory for Space Sciences and Physics Department, Campus Box 1105, Washington University, St. Louis, MO 63130 (United States)
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland)
- Department of Physics and Astronomy, University of Victoria, Canada, P.O. Box 3055, Victoria, BC V8W 3P6 (Canada)
- Publication Date:
- OSTI Identifier:
- 22224069
- Resource Type:
- Journal Article
- Journal Name:
- Astrophysical Journal Letters
- Additional Journal Information:
- Journal Volume: 776; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ALUMINIUM 26; ALUMINIUM 27; CARBON 12; CARBON 13; ISOTOPE RATIO; NITROGEN 10; ORIGIN; S PROCESS; SILICON 32; SILICON CARBIDES; STAR MODELS; SULFUR 32; SUPERNOVAE; TITANIUM 44
Citation Formats
Fujiya, Wataru, Hoppe, Peter, Zinner, Ernst, Pignatari, Marco, and Herwig, Falk. EVIDENCE FOR RADIOGENIC SULFUR-32 IN TYPE AB PRESOLAR SILICON CARBIDE GRAINS?. United States: N. p., 2013.
Web. doi:10.1088/2041-8205/776/2/L29.
Fujiya, Wataru, Hoppe, Peter, Zinner, Ernst, Pignatari, Marco, & Herwig, Falk. EVIDENCE FOR RADIOGENIC SULFUR-32 IN TYPE AB PRESOLAR SILICON CARBIDE GRAINS?. United States. https://doi.org/10.1088/2041-8205/776/2/L29
Fujiya, Wataru, Hoppe, Peter, Zinner, Ernst, Pignatari, Marco, and Herwig, Falk. 2013.
"EVIDENCE FOR RADIOGENIC SULFUR-32 IN TYPE AB PRESOLAR SILICON CARBIDE GRAINS?". United States. https://doi.org/10.1088/2041-8205/776/2/L29.
@article{osti_22224069,
title = {EVIDENCE FOR RADIOGENIC SULFUR-32 IN TYPE AB PRESOLAR SILICON CARBIDE GRAINS?},
author = {Fujiya, Wataru and Hoppe, Peter and Zinner, Ernst and Pignatari, Marco and Herwig, Falk},
abstractNote = {We report C, Si, and S isotope measurements on 34 presolar silicon carbide grains of Type AB, characterized by {sup 12}C/{sup 13}C < 10. Nitrogen, Mg-Al-, and Ca-Ti-isotopic compositions were measured on a subset of these grains. Three grains show large {sup 32}S excesses, a signature that has been previously observed for grains from supernovae (SNe). Enrichments in {sup 32}S may be due to contributions from the Si/S zone and the result of S molecule chemistry in still unmixed SN ejecta or due to incorporation of radioactive {sup 32}Si from C-rich explosive He shell ejecta. However, a SN origin remains unlikely for the three AB grains considered here, because of missing evidence for {sup 44}Ti, relatively low {sup 26}Al/{sup 27}Al ratios (a few times 10{sup –3}), and radiogenic {sup 32}S along with low {sup 12}C/{sup 13}C ratios. Instead, we show that born-again asymptotic giant branch (AGB) stars that have undergone a very-late thermal pulse (VLTP), known to have low {sup 12}C/{sup 13}C ratios and enhanced abundances of the light s-process elements, can produce {sup 32}Si, which makes such stars attractive sources for AB grains with {sup 32}S excesses. This lends support to the proposal that at least some AB grains originate from born-again AGB stars, although uncertainties in the born-again AGB star models and possible variations of initial S-isotopic compositions in the parent stars of AB grains make it difficult to draw a definitive conclusion.},
doi = {10.1088/2041-8205/776/2/L29},
url = {https://www.osti.gov/biblio/22224069},
journal = {Astrophysical Journal Letters},
issn = {2041-8205},
number = 2,
volume = 776,
place = {United States},
year = {Sun Oct 20 00:00:00 EDT 2013},
month = {Sun Oct 20 00:00:00 EDT 2013}
}