A CRITICAL EXAMINATION OF THE X-WIND MODEL FOR CHONDRULE AND CALCIUM-RICH, ALUMINUM-RICH INCLUSION FORMATION AND RADIONUCLIDE PRODUCTION
- School of Earth and Space Exploration, Arizona State University, P.O. Box 871404, Tempe, AZ 85287-1404 (United States)
- Kingsborough Community College and the Graduate Center of the City University of New York, 2001 Oriental Boulevard, Brooklyn, NY 11235-2398 (United States)
Meteoritic data, especially regarding chondrules and calcium-rich, aluminum-rich inclusions (CAIs), and isotopic evidence for short-lived radionuclides (SLRs) in the solar nebula, potentially can constrain how planetary systems form. Interpretation of these data demands an astrophysical model, and the 'X-wind' model of Shu et al. and collaborators has been advanced to explain the origin of chondrules, CAIs, and SLRs. It posits that chondrules and CAIs were thermally processed <0.1 AU from the protostar, then flung by a magnetocentrifugal outflow to the 2-3 AU region to be incorporated into chondrites. Here we critically examine key assumptions and predictions of the X-wind model. We find a number of internal inconsistencies: theory and observation show no solid material exists at 0.1 AU; particles at 0.1 AU cannot escape being accreted into the star; particles at 0.1 AU will collide at speeds high enough to destroy them; thermal sputtering will prevent growth of particles; and launching of particles in magnetocentrifugal outflows is not modeled, and may not be possible. We also identify a number of incorrect predictions of the X-wind model: the oxygen fugacity where CAIs form is orders of magnitude too oxidizing, chondrule cooling rates are orders of magnitude lower than those experienced by barred olivine chondrules, chondrule-matrix complementarity is not predicted, and the SLRs are not produced in their observed proportions. We conclude that the X-wind model is not relevant to chondrule and CAI formation and SLR production. We discuss more plausible models for chondrule and CAI formation and SLR production.
- OSTI ID:
- 21474420
- Journal Information:
- Astrophysical Journal, Vol. 725, Issue 1; Other Information: DOI: 10.1088/0004-637X/725/1/692; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COSMOLOGY AND ASTRONOMY
ALUMINIUM
ASTROPHYSICS
CALCIUM
CHONDRITES
METEOROIDS
OLIVINE
OXYGEN
PROTOPLANETS
PROTOSTARS
SHOCK WAVES
SOLAR NEBULA
STELLAR WINDS
SUPERNOVAE
ALKALINE EARTH METALS
BINARY STARS
ELEMENTS
ERUPTIVE VARIABLE STARS
METALS
METEORITES
MINERALS
NEBULAE
NONMETALS
PHYSICS
SILICATE MINERALS
STARS
STELLAR ACTIVITY
STONE METEORITES
VARIABLE STARS