AUTOMATED NanoSIMS MEASUREMENTS OF SPINEL STARDUST FROM THE MURRAY METEORITE

Journal Article · Thu Jul 01 00:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/717/1/107· OSTI ID:21457127

Gyngard, Frank; Zinner, Ernst; Stadermann, Frank J; Hynes, K Mairin ^[1]; Nittler, Larry R ^[2]; Morgand, Alain ^[3]

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1. Laboratory for Space Sciences and Department of Physics, Washington University, One Brookings Drive, St. Louis, MO 63130 (United States)
2. Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road NW, Washington, DC 20015 (United States)
3. Cameca, 29 Quai des Gresillons, Gennevilliers, 92622 Cedex (France)

We report new O isotopic data on 41 presolar oxide grains, 38 MgAl{sub 2}O{sub 4} (spinel) and 3 Al{sub 2}O{sub 3} from the CM2 meteorite Murray, identified with a recently developed automated measurement system for NanoSIMS. We have also obtained Mg-Al isotopic results on 29 of the same grains (26 spinel and 3 Al{sub 2}O{sub 3}). The majority of the grains have O isotopic compositions typical of most presolar oxides, fall well into the four previously defined groups, and are most likely condensates from either red giant branch or asymptotic giant branch stars. We have also discovered several grains with more unusual O and Mg compositions suggesting formation in extreme astrophysical environments, such as novae and supernovae (SNe). One of these grains has massive enrichments in {sup 17}O, {sup 25}Mg, and {sup 26}Mg, which are isotopic signatures indicative of condensation from nova ejecta. Two grains of SN origin were also discovered: one has a large {sup 18}O/{sup 16}O ratio typical of Group 4 presolar oxides; another grain is substantially enriched in {sup 16}O, and also contains radiogenic {sup 44}Ca from the decay of {sup 44}Ti, a likely condensate from material originating in the O-rich inner zones of a Type II SN. In addition, several Group 2 presolar spinel grains also have large {sup 25}Mg and {sup 26}Mg isotopic anomalies that are difficult to explain by standard nucleosynthesis in low-mass stars. Auger elemental spectral analyses were performed on the grains and qualitatively suggest that presolar spinel may not have higher-than-stoichiometric Al/Mg ratios, in contrast to SIMS results obtained here and reported previously.

• OSTI ID: 21457127
• Journal Information: Astrophysical Journal, Vol. 717, Issue 1; Other Information: DOI: 10.1088/0004-637X/717/1/107; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ABUNDANCE
ALUMINIUM OXIDES
ASTROPHYSICS
CALCIUM 44
ISOTOPE RATIO
MAGNESIUM 25
MAGNESIUM 26
MASS SPECTROSCOPY
METEORITES
NOVAE
NUCLEAR REACTIONS
NUCLEOSYNTHESIS
OXYGEN 16
OXYGEN 17
OXYGEN 18
STOICHIOMETRY
SUPERNOVAE
TITANIUM 44
ALKALINE EARTH ISOTOPES
ALUMINIUM COMPOUNDS
BETA DECAY RADIOISOTOPES
BINARY STARS
CALCIUM ISOTOPES
CHALCOGENIDES
DIMENSIONLESS NUMBERS
ELECTRON CAPTURE RADIOISOTOPES
ERUPTIVE VARIABLE STARS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
INTERMEDIATE MASS NUCLEI
ISOTOPES
LIGHT NUCLEI
MAGNESIUM ISOTOPES
NUCLEI
OXIDES
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
PHYSICS
RADIOISOTOPES
SPECTROSCOPY
STABLE ISOTOPES
STARS
SYNTHESIS
TITANIUM ISOTOPES
VARIABLE STARS
YEARS LIVING RADIOISOTOPES