UNUSUAL {sup 29,30}Si-RICH SiCs OF MASSIVE STAR ORIGIN FOUND WITHIN GRAPHITES FROM THE MURCHISON METEORITE

Journal Article · Tue Jun 15 00:00:00 EDT 2010 · Astronomical Journal (New York, N.Y. Online)

DOI:https://doi.org/10.1088/0004-6256/139/6/2159· OSTI ID:21443100

Croat, T K; Stadermann, F J; Bernatowicz, T J ^[1]

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1. Department of Physics and Laboratory for Space Science, Washington University, Campus Box 1105, One Brookings Drive, St. Louis, MO 63130-4899 (United States)

Correlated transmission electron microscopy and NanoSIMS isotopic studies have revealed two unusual SiCs with large {sup 29,30}Si enrichments within micron-sized graphites from the Murchison meteorite. Such anomalies are rare among the overall SiC population (in <<0.01% of SiCs yet measured), whereas two of the three SiCs found within graphite show {sup 29,30}Si enrichments, in one case as large as {sup 29}Si/{sup 28}Si = (2.28 {+-} 0.03) x solar and {sup 30}Si/{sup 28}Si = (2.03 {+-} 0.03)x solar. C-burning and Ne-burning in massive stars (>8 M{sub sun} initial mass) during their post-main-sequence development are the only processes capable of producing sufficiently large {sup 29,30}Si enrichments. This material with heavy Si isotopic enrichments from the O/Ne and O/Si layers is later incorporated into carbonaceous stardust, either in ejecta from Type II supernovae or perhaps in the colliding winds of Wolf-Rayet binaries. Although often too small for Si isotopic measurements, four other SiC-containing graphites show other signatures of a massive star origin. Abundance estimates suggest that such unusual SiCs are present within {approx}1% of high-density graphites. This abundance can be reconciled with the much lower abundance in the overall SiC population if these unusual SiCs are naturally smaller ({approx}200 nm or less) than SiCs from other isotopic subgroups and if differential destruction of small unusual SiCs occurs in massive star outflows unless these SiCs are encapsulated in graphite.

• OSTI ID: 21443100
• Journal Information: Astronomical Journal (New York, N.Y. Online), Vol. 139, Issue 6; Other Information: DOI: 10.1088/0004-6256/139/6/2159; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
DUSTS
GRAPHITE
METEORITES
NUCLEAR REACTIONS
NUCLEOSYNTHESIS
SILICON 28
SILICON 29
SILICON 30
SILICON CARBIDES
SUPERNOVAE
BINARY STARS
CARBIDES
CARBON
CARBON COMPOUNDS
ELEMENTS
ERUPTIVE VARIABLE STARS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
ISOTOPES
LIGHT NUCLEI
MINERALS
NONMETALS
NUCLEI
SILICON COMPOUNDS
SILICON ISOTOPES
STABLE ISOTOPES
STARS
SYNTHESIS
VARIABLE STARS