ON THE OXYGEN ISOTOPIC COMPOSITION OF THE SOLAR SYSTEM
- Department of Geology and Geophysics, University of Hawaii, Honolulu, HI, 96822 (United States)
The {sup 18}O/{sup 17}O ratio of the solar system is 5.2 while that of the interstellar medium (ISM) and young stellar objects is approx4. This difference cannot be explained by pollution of the Sun's natal molecular cloud by {sup 18}O-rich supernova ejecta because (1) the necessary B-star progenitors live longer than the duration of star formation in molecular clouds, (2) the delivery of ejecta gas is too inefficient and the amount of dust in supernova ejecta is too small compared to the required pollution (2% of total mass or approx20% of oxygen), and (3) the predicted amounts of concomitant short-lived radionuclides (SLRs) conflicts with the abundances of {sup 26}Al and {sup 41}Ca in the early solar system. Proposals for the introduction of {sup 18}O-rich material must also be consistent with any explanation for the origin of the observed slope-one relationship between {sup 17}O/{sup 16}O and {sup 18}O/{sup 16}O in the high-temperature components of primitive meteorites. The difference in {sup 18}O/{sup 17}O ratios can be explained by enrichment of the ISM by the {sup 17}O-rich winds of asymptotic giant branch (AGB) stars, the sequestration of comparatively {sup 18}O-rich gas from star-forming regions into long-lived, low-mass stars, and a monotonic decrease in the {sup 18}O/{sup 17}O ratio of interstellar gas. At plausible rates of star formation and gas infall, Galactic chemical evolution does not follow a slope-one line in a three-isotope plot, but instead moves along a steeper trajectory toward an {sup 17}O-rich state. Evolution of the ISM and star-forming gas by AGB winds also explains the difference in the carbon isotope ratios of the solar system and ISM.
- OSTI ID:
- 21378268
- Journal Information:
- Astrophysical Journal (Online), Vol. 705, Issue 2; Other Information: DOI: 10.1088/0004-637X/705/2/L163; ISSN 1538-4357
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COSMOLOGY AND ASTRONOMY
ABUNDANCE
ALUMINIUM 26
CALCIUM 41
CARBON ISOTOPES
DUSTS
GALACTIC EVOLUTION
GALAXIES
ISOTOPE RATIO
MASS
METEORITES
OXYGEN 16
OXYGEN 17
OXYGEN 18
SOLAR SYSTEM
SUN
ALKALINE EARTH ISOTOPES
ALUMINIUM ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
CALCIUM ISOTOPES
DIMENSIONLESS NUMBERS
ELECTRON CAPTURE RADIOISOTOPES
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
EVOLUTION
INTERMEDIATE MASS NUCLEI
ISOTOPES
LIGHT NUCLEI
MAIN SEQUENCE STARS
NUCLEI
ODD-ODD NUCLEI
OXYGEN ISOTOPES
RADIOISOTOPES
SECONDS LIVING RADIOISOTOPES
STABLE ISOTOPES
STARS
YEARS LIVING RADIOISOTOPES