Modeling the Dynamical Coupling of Solar Convection with the Radiative Interior

The global dynamics of a rotating star like the Sun involves the coupling of a highly turbulent convective envelope overlying a seemingly benign radiative interior. We use the anelastic spherical harmonic code to develop a new class of three-dimensional models that nonlinearly couple the convective...

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Bibliographic Details
Published in:The Astrophysical journal 2011-12, Vol.742 (2), p.79-jQuery1323901167348='48'
Main Authors: Brun, Allan Sacha, Miesch, Mark S, Toomre, Juri
Format: Article
Language:English
Subjects:
ANGULAR MOMENTUM
Astronomy
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
CONVECTION
Earth, ocean, space
Exact sciences and technology
GRAVITY WAVES
NUCLEAR CORES
PENETRATION DEPTH
ROTATION
Sciences of the Universe
SOLAR ACTIVITY
SOLAR CORONA
STRATIFICATION
SUN
THREE-DIMENSIONAL CALCULATIONS
TURBULENCE
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Summary:The global dynamics of a rotating star like the Sun involves the coupling of a highly turbulent convective envelope overlying a seemingly benign radiative interior. We use the anelastic spherical harmonic code to develop a new class of three-dimensional models that nonlinearly couple the convective envelope to a deep stable radiative interior. The numerical simulation assumes a realistic solar stratification from r = 0.07 up to 0.97R (with R the solar radius), thus encompassing part of the nuclear core up through most of the convection zone. We find that a tachocline naturally establishes itself between the differentially rotating convective envelope and the solid body rotation of the interior, with a slow spreading that is here diffusively controlled. The rapid angular momentum redistribution in the convective envelope leads to a fast equator and slow poles, with a conical differential rotation achieved at mid-latitudes, much as has been deduced by helioseismology. The convective motions are able to overshoot downward about 0.04R into the radiative interior. However, the convective meridional circulation there is confined to a smaller penetration depth and is directed mostly equatorward at the base of the convection zone. Thermal wind balance is established in the lower convection zone and tachocline but departures are evident in the upper convection zone. Internal gravity waves are excited by the convective overshooting, yielding a complex wave field throughout the radiative interior.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/742/2/79