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[7.15] A Strictly Hydrodynamic Treatment of Convective Overshooting in Stars

P. A. Young, D. Arnett (Steward Observatory)

We have developed a physically motivated prescription for extra mixing in stars from convective overshooting. The formulation is based upon a strictly hydrodynamic treatment of the boundary zone of the convective region informed by three dimensional hydrodynamic simulations. Gravity waves excited by motion of convective fluid elements are dissipated turbulently, resulting in mixing. More vigorous convection in massive stars results in more mixing, naturally producing a scaling in the degree of overshooting with mass as implied by earlier work. Implementation of the algorithm in the stellar evolution code TYCHO produces carbon stars on the asymptotic giant branch as well as evolutionary tracks for the Pleiades consistent with the lithium depletion age of the cluster determined from brown dwarfs.

This work was supported by DOE, grant number DE-FG03-98DP00214/A001

The author(s) of this abstract have provided an email address for comments about the abstract: payoung@as.arizona.edu

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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.