THERMOHALINE MIXING: DOES IT REALLY GOVERN THE ATMOSPHERIC CHEMICAL COMPOSITION OF LOW-MASS RED GIANTS?

Journal Article · Thu Jan 20 00:00:00 EST 2011 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/727/1/L8· OSTI ID:21560567

Denissenkov, Pavel A ^[1]

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1. Department of Physics and Astronomy, University of Victoria, P.O. Box 3055, Victoria, BC, V8W 3P6 (Canada)

First results of our three-dimensional numerical simulations of thermohaline convection driven by {sup 3}He burning in a low-mass red giant branch (RGB) star at the bump luminosity are presented. They confirm our previous conclusion that this convection has a mixing rate that is a factor of 50 lower than the observationally constrained rate of RGB extra-mixing. It is also shown that the large-scale instabilities of the salt-fingering mean field (those of the Boussinesq and advection-diffusion equations averaged over length and timescales of many salt fingers), which have been observed to increase the rate of oceanic thermohaline mixing up to one order of magnitude, do not enhance the RGB thermohaline mixing. We speculate on possible alternative solutions of the problem of RGB extra-mixing, among which the most promising one that is related to thermohaline mixing takes advantage of the shifting of the salt-finger spectrum toward larger diameters by toroidal magnetic field.

• OSTI ID: 21560567
• Journal Information: Astrophysical Journal Letters, Vol. 727, Issue 1; Other Information: DOI: 10.1088/2041-8205/727/1/L8; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ABUNDANCE
CHEMICAL COMPOSITION
COMPUTERIZED SIMULATION
CONVECTION
DIFFUSION EQUATIONS
MIXING
RED GIANT STARS
THREE-DIMENSIONAL CALCULATIONS
DIFFERENTIAL EQUATIONS
ENERGY TRANSFER
EQUATIONS
GIANT STARS
HEAT TRANSFER
MASS TRANSFER
PARTIAL DIFFERENTIAL EQUATIONS
SIMULATION
STARS