NUMERICAL SIMULATIONS OF THERMOHALINE CONVECTION: IMPLICATIONS FOR EXTRA-MIXING IN LOW-MASS RGB STARS
- Department of Physics and Astronomy, University of Victoria, P.O. Box 3055, Victoria, B.C., V8W 3P6 (Canada)
Low-mass stars are known to experience extra-mixing in their radiative zones on the red giant branch (RGB) above the bump luminosity. To determine if the salt-fingering transport of chemical composition driven by {sup 3}He burning is efficient enough to produce RGB extra-mixing, two-dimensional numerical simulations of thermohaline convection for physical conditions corresponding to the RGB case have been carried out. We have found that the effective ratio of a salt finger's length to its diameter a{sub eff} {approx}< 0.5 is more than 10 times smaller than the value needed to reproduce observations (a{sub obs} {approx}> 7). On the other hand, using the thermohaline diffusion coefficient from linear stability analysis together with a = a{sub obs} is able to describe the RGB extra-mixing at all metallicities so well that it is tempting to believe that it may represent the true mechanism. In view of these results, follow-up three-dimensional numerical simulations of thermohaline convection for the RGB case are clearly needed.
- OSTI ID:
- 21467187
- Journal Information:
- Astrophysical Journal, Vol. 723, Issue 1; Other Information: DOI: 10.1088/0004-637X/723/1/563; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ABUNDANCE
CHEMICAL COMPOSITION
COMPUTERIZED SIMULATION
HELIUM 3
LUMINOSITY
MASS
STAR EVOLUTION
STARS
THREE-DIMENSIONAL CALCULATIONS
TWO-DIMENSIONAL CALCULATIONS
EVEN-ODD NUCLEI
EVOLUTION
HELIUM ISOTOPES
ISOTOPES
LIGHT NUCLEI
NUCLEI
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
SIMULATION
STABLE ISOTOPES