A critical examination of the x-wind model for chondrule and calcium-rich, aluminum-rich inclusion formation and radionuclide production

Steven Desch, M. A. Morris, H. C. Connolly, Alan P. Boss

Research output: Contribution to journalArticle

43 Citations (Scopus)

Abstract

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 <0.1AU from the protostar, then flung by a magnetocentrifugal outflow to the 2-3AU 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 0.1AU; particles at 0.1AU cannot escape being accreted into the star; particles at 0.1AU 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-windmodel: the oxygen fugacity where CAIs form is orders ofmagnitude 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.

Original languageEnglish (US)
Pages (from-to)692-711
Number of pages20
JournalAstrophysical Journal
Volume725
Issue number1
DOIs
StatePublished - Dec 10 2010

Fingerprint

chondrule
radioactive isotopes
radionuclide
calcium
aluminum
examination
inclusions
outflow
solar nebula
planetary systems
protostars
launching
chondrites
complementarity
fugacity
prediction
predictions
chondrite
olivine
escape

Keywords

  • Meteorites, meteors, meteoroids
  • Protoplanetary disks
  • Shock waves
  • Stars:protostars
  • Supernovae: general

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

A critical examination of the x-wind model for chondrule and calcium-rich, aluminum-rich inclusion formation and radionuclide production. / Desch, Steven; Morris, M. A.; Connolly, H. C.; Boss, Alan P.

In: Astrophysical Journal, Vol. 725, No. 1, 10.12.2010, p. 692-711.

Research output: Contribution to journalArticle

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