Time-dependent turbulence in stars

W. David Arnett, Casey Meakin

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

Abstract

Three-dimensional (3D) hydrodynamic simulations of shell oxygen burning by Meakin & Arnett (2007b) exhibit bursty, recurrent fluctuations in turbulent kinetic energy. These are shown to be due to a global instability in the convective region, which has been suppressed in simulations of stellar evolution which use mixing-length theory (MLT). Quantitatively similar behavior occurs in the model of a convective roll (cell) of Lorenz (1963), which is known to have a strange attractor that gives rise to random fluctuations in time. An extension of the Lorenz model, which includes Kolmogorov damping and nuclear burning, is shown to exhibit bursty, recurrent fluctuations like those seen in the 3D simulations. A simple model of a convective layer (composed of multiple Lorenz cells) gives luminosity fluctuations which are suggestive of irregular variables (red giants and supergiants, see Schwarzschild (1975). Details and additional discussion may be found in Arnett & Meakin (2011). Apparent inconsistencies between Arnett, Meakin, & Young (2009) and Nordlund, Stein, & Asplund (2009) on the nature of convective driving have been resolved, and are discussed.

Original languageEnglish (US)
Title of host publicationAstrophysical Dynamics
Subtitle of host publicationFrom Stars to Galaxies
EditorsNicholas Brummell, Sacha Brun, Mark Boulder, Yannick Ponty
Pages205-212
Number of pages8
EditionS271
DOIs
StatePublished - Jun 1 2010

Publication series

NameProceedings of the International Astronomical Union
NumberS271
Volume6
ISSN (Print)1743-9213
ISSN (Electronic)1743-9221

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Keywords

  • Convection
  • Irregular variables
  • Turbulence

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Astronomy and Astrophysics
  • Nutrition and Dietetics
  • Public Health, Environmental and Occupational Health
  • Space and Planetary Science

Cite this

David Arnett, W., & Meakin, C. (2010). Time-dependent turbulence in stars. In N. Brummell, S. Brun, M. Boulder, & Y. Ponty (Eds.), Astrophysical Dynamics: From Stars to Galaxies (S271 ed., pp. 205-212). (Proceedings of the International Astronomical Union; Vol. 6, No. S271). https://doi.org/10.1017/S1743921311017625