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Title: Differential rotation in solar-like stars from global simulations

Abstract

To explore the physics of large-scale flows in solar-like stars, we perform three-dimensional anelastic simulations of rotating convection for global models with stratification resembling the solar interior. The numerical method is based on an implicit large-eddy simulation approach designed to capture effects from non-resolved small scales. We obtain two regimes of differential rotation, with equatorial zonal flows accelerated either in the direction of rotation (solar-like) or in the opposite direction (anti-solar). While the models with the solar-like differential rotation tend to produce multiple cells of meridional circulation, the models with anti-solar differential rotation result in only one or two meridional cells. Our simulations indicate that the rotation and large-scale flow patterns critically depend on the ratio between buoyancy and Coriolis forces. By including a sub-adiabatic layer at the bottom of the domain, corresponding to the stratification of a radiative zone, we reproduce a layer of strong radial shear similar to the solar tachocline. Similarly, enhanced super-adiabaticity at the top results in a near-surface shear layer located mainly at lower latitudes. The models reveal a latitudinal entropy gradient localized at the base of the convection zone and in the stable region, which, however, does not propagate across the convection zone. Inmore » consequence, baroclinicity effects remain small, and the rotation isocontours align in cylinders along the rotation axis. Our results confirm the alignment of large convective cells along the rotation axis in the deep convection zone and suggest that such 'banana-cell' pattern can be hidden beneath the supergranulation layer.« less

Authors:
;  [1];  [2]
  1. Solar Physics, HEPL, Stanford University, 452 Lomita Mall, Stanford, CA 94305-4085 (United States)
  2. European Centre for Medium-Range Weather Forecasts, Reading RG2 9AX (United Kingdom)
Publication Date:
OSTI Identifier:
22348390
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 779; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CAPTURE; CONVECTION; CORIOLIS FORCE; ENTROPY; LARGE-EDDY SIMULATION; LAYERS; ROTATION; SOLAR GRANULATION; STARS; STRATIFICATION; SUN; SURFACES

Citation Formats

Guerrero, G., Kosovichev, A. G., Smolarkiewicz, P. K., and Mansour, N. N., E-mail: gag@stanford.edu, E-mail: sasha@sun.stanford.edu, E-mail: smolar@ecmwf.int, E-mail: nagi.n.mansour@nasa.gov. Differential rotation in solar-like stars from global simulations. United States: N. p., 2013. Web. doi:10.1088/0004-637X/779/2/176.
Guerrero, G., Kosovichev, A. G., Smolarkiewicz, P. K., & Mansour, N. N., E-mail: gag@stanford.edu, E-mail: sasha@sun.stanford.edu, E-mail: smolar@ecmwf.int, E-mail: nagi.n.mansour@nasa.gov. Differential rotation in solar-like stars from global simulations. United States. https://doi.org/10.1088/0004-637X/779/2/176
Guerrero, G., Kosovichev, A. G., Smolarkiewicz, P. K., and Mansour, N. N., E-mail: gag@stanford.edu, E-mail: sasha@sun.stanford.edu, E-mail: smolar@ecmwf.int, E-mail: nagi.n.mansour@nasa.gov. 2013. "Differential rotation in solar-like stars from global simulations". United States. https://doi.org/10.1088/0004-637X/779/2/176.
@article{osti_22348390,
title = {Differential rotation in solar-like stars from global simulations},
author = {Guerrero, G. and Kosovichev, A. G. and Smolarkiewicz, P. K. and Mansour, N. N., E-mail: gag@stanford.edu, E-mail: sasha@sun.stanford.edu, E-mail: smolar@ecmwf.int, E-mail: nagi.n.mansour@nasa.gov},
abstractNote = {To explore the physics of large-scale flows in solar-like stars, we perform three-dimensional anelastic simulations of rotating convection for global models with stratification resembling the solar interior. The numerical method is based on an implicit large-eddy simulation approach designed to capture effects from non-resolved small scales. We obtain two regimes of differential rotation, with equatorial zonal flows accelerated either in the direction of rotation (solar-like) or in the opposite direction (anti-solar). While the models with the solar-like differential rotation tend to produce multiple cells of meridional circulation, the models with anti-solar differential rotation result in only one or two meridional cells. Our simulations indicate that the rotation and large-scale flow patterns critically depend on the ratio between buoyancy and Coriolis forces. By including a sub-adiabatic layer at the bottom of the domain, corresponding to the stratification of a radiative zone, we reproduce a layer of strong radial shear similar to the solar tachocline. Similarly, enhanced super-adiabaticity at the top results in a near-surface shear layer located mainly at lower latitudes. The models reveal a latitudinal entropy gradient localized at the base of the convection zone and in the stable region, which, however, does not propagate across the convection zone. In consequence, baroclinicity effects remain small, and the rotation isocontours align in cylinders along the rotation axis. Our results confirm the alignment of large convective cells along the rotation axis in the deep convection zone and suggest that such 'banana-cell' pattern can be hidden beneath the supergranulation layer.},
doi = {10.1088/0004-637X/779/2/176},
url = {https://www.osti.gov/biblio/22348390}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 779,
place = {United States},
year = {Fri Dec 20 00:00:00 EST 2013},
month = {Fri Dec 20 00:00:00 EST 2013}
}