Theory and numerics: New results on convection in stars

David Arnett, Casey Meakin, Sumner Starrfield, Francis Timmes, Patrick Young

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

Abstract

We have begun a new program to improve the treatment of turbulent convection in stars; it features Convection Algorithms Based on Simulations (CABS). We analyze stellar convection with the aid of 3D hydrodynamic simulations, introducing the turbulent cascade into our theoretical analysis. We devise closures of the Reynolds-decomposed mean field equations by simple physical modeling of the simulations. The procedure is testable and allows systematic improvement. The interpretation of mixing-length theory (MLT) as generally used in astrophysics is incorrect. Direct tests show that the damping associated with the turbulent cascade is that suggested by Kolmogorov [1] (εK≈(u′)3rms/lCZ), where lCZ is the depth of the convection zone. This implies that the mixing-length parameter α is a simple function of depth of the convection zone, and not freely adjustable. Appropriate adjustment of another parameter of MLT, the "geometric factor", can leave solar models almost unchanged, except for their velocity scale. This parameter adjusts the super-adiabatic region just below the photosphere, and represents a crude interpolation function for characterizing 3D hydrodynamic atmospheres.

Original languageEnglish (US)
Title of host publicationNinth Torino Workshop on Evolution and Nucleosynthesis in AGB Stars and the Second Perugia Workshop on Nuclear Astrophysics
Pages287-294
Number of pages8
DOIs
StatePublished - Dec 1 2008
Event9th Torino Workshop on Evolution and Nucleosynthesis in AGB Stars and the 2nd Perugia Workshop on Nuclear Astrophysics - Perugia, Italy
Duration: Oct 21 2007Oct 27 2007

Publication series

NameAIP Conference Proceedings
Volume1001
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Other

Other9th Torino Workshop on Evolution and Nucleosynthesis in AGB Stars and the 2nd Perugia Workshop on Nuclear Astrophysics
CountryItaly
CityPerugia
Period10/21/0710/27/07

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Keywords

  • Hydrodynamics
  • Stars
  • Stellar Evolution
  • Turbulence

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Arnett, D., Meakin, C., Starrfield, S., Timmes, F., & Young, P. (2008). Theory and numerics: New results on convection in stars. In Ninth Torino Workshop on Evolution and Nucleosynthesis in AGB Stars and the Second Perugia Workshop on Nuclear Astrophysics (pp. 287-294). (AIP Conference Proceedings; Vol. 1001). https://doi.org/10.1063/1.2916977