Spherical-shell boundaries for two-dimensional compressible convection in a star

Abstract

Context: We study the impact of two-dimensional spherical shells on compressible convection. Realistic profiles for density and temperature from a one-dimensional stellar evolution code are used to produce a model of a large stellar convection zone representative of a young low-mass star. Methods: We perform hydrodynamic implicit large-eddy simulations of compressible convection using the MUltidimensional Stellar Implicit Code (MUSIC). Because MUSIC has been designed to use realistic stellar models produced from one-dimensional stellar evolution calculations, MUSIC simulations are capable of seamlessly modeling a whole star. Simulations in two-dimensional spherical shells that have different radial extents are performed over hundreds of convective turnover times, permitting the collection of well-converged statistics. Results: We evaluate basic statistics of the convective turnover time, the convective velocity, and the overshooting layer. These quantities are selected for their relevance to one-dimensional stellar evolution calculations, so that our results are focused toward the 321D link. The inclusion in the spherical shell of the boundary between the radiative and convection zones decreases the amplitude of convective velocities in the convection zone. The inclusion of near-surface layers in the spherical shell can increase the amplitude of convective velocities, although the radial structure of the velocity profile established by deep convection is unchanged. The impact from including the near-surface layers depends on the speed and structure of small-scale convection in the near-surface layers. Larger convective velocities in the convection zone result in a commensurate increase in the overshooting layer width and decrease in the convective turnover time. These results provide support for non-local aspects of convection.

14 pages, 9 figures, abbreviated abstract, accepted for publication in Astronomy & Astrophysics, reproduced with permission, c ESO

References in corpus (10)

• The Mass-Dependence of Angular Momentum Evolution in Sun-Like Stars
• Improvements to stellar structure models, based on a grid of 3D convection simulations. II. Calibrating the mixing-length formulation
• Prandtl number dependence of convection driven dynamos in rotating spherical fluid shells
• Magnetic confinement of the solar tachocline: II. Coupling to a convection zone
• Reynolds stress and heat flux in spherical shell convection
• Numerical Simulations of Penetration and Overshoot in the Sun
• Anelastic Versus Fully Compressible Turbulent Rayleigh-Bénard Convection
• Conduction in low Mach number flows: Part I Linear & weakly nonlinear regimes
• On the effect of overshooting as predicted by the modelling of the pre-main sequence evolution of a 2 solar-mass star
• Turbulent 3D MHD dynamo model in spherical shells: Regular oscillations of the dipolar field

Cited by in corpus (8)

• Lithium depletion in solar-like stars: effect of overshooting based on realistic multi-dimensional simulations
• Extreme value statistics for two-dimensional convective penetration in a pre-Main Sequence star
• Calibrating Core Overshooting Parameters With Two-dimensional Hydrodynamical Simulations
• Benchmarking the Multi-dimensional Stellar Implicit Code MUSIC
• Two-dimensional simulations of solar-like models with artificially enhanced luminosity -- I. Impact on convective penetration
• Two-dimensional simulations of solar-like models with artificially enhanced luminosity. II. Impact on internal gravity waves
• Theoretical predictions of surface light element abundances in protostellar and pre-Main Sequence phase
• Suppression of lithium depletion in young low-mass stars from fast rotation