view Abstract Citations (113) References (30) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Oxygen Isotopes in Circumstellar AL 2O 3 Grains from Meteorites and Stellar Nucleosynthesis Huss, Gary R. ; Fahey, Albert J. ; Gallino, Roberto ; Wasserburg, G. J. Abstract We have found a approximately 3 micrometer Al2O3 grain (B39) in the Bishunpur LL3.1 chondrite that is enriched in 0-17 by a factor of approximately 6.8 (0-16/0-17 = 385 +/- 9) and depleted in 0-18 by almost 60% (0-16/0-18 = 853 +/- 30) relative to solar system oxygen and has an initial Al-26/Al-27 = 1.7 +/- 0.2 x 10 3, approximately 34 times greater than the initial solar system value. The isotopic compositions of B39 and two other Al2O3 grains previously reported from the Orgueil and Murchison meteorites show that these grains formed directly from the ejecta of low-mass AGB stars with C/O less than 1. A simple theoretical analysis is presented showing that the oxygen systematics of the grains are a natural consequence of main-sequence evolution followed by first dredge-up Al-26 is the result of third dredge-up. Circumstellar Al2O3 grains provide very precise isotopic data for stellar ejecta that complement spectroscopic observations of oxygen-rich stars. Isotopic differences indicate that the Al2O3 grains come from separate stars of different mass and intital oxygen composition that originated in molecular clouds different from the one in which the solar system formed. Publication: The Astrophysical Journal Pub Date: July 1994 DOI: 10.1086/187443 Bibcode: 1994ApJ...430L..81H Keywords: Aluminum Isotopes; Meteoritic Composition; Oxygen Isotopes; Stellar Envelopes; Aluminum Oxides; Asymptotic Giant Branch Stars; Chondrites; Murchison Meteorite; Orgueil Meteorite; Stellar Evolution; Stellar Mass; Astrophysics; STARS: CIRCUMSTELLAR MATTER; ISM: DUST; EXTINCTION; NUCLEAR REACTIONS; NUCLEOSYNTHESIS; ABUNDANCES; STARS: AGB AND POST-AGB; SOLAR SYSTEM: FORMATION full text sources ADS |