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  • 3D Hydrodynamic Simulations of Massive Main-sequence Stars. III. The Effect of Radiation Pressure and Diffusion Leading to a 1D Equilibrium Model
Title: 3D Hydrodynamic Simulations of Massive Main-sequence Stars. III. The Effect of Radiation Pressure and Diffusion Leading to a 1D Equilibrium Model
Abstract We present 3D hydrodynamical simulations of core convection with a stably stratified envelope of a 25M⊙star in the early phase of the main sequence. We use the explicit gas-dynamics codePPMstar, which tracks two fluids and includes radiation pressure and radiative diffusion. Multiple series of simulations with different luminosities and radiative thermal conductivities are presented. The entrainment rate at the convective boundary, internal gravity waves in and above the boundary region, and the approach to dynamical equilibrium shortly after a few convective turnovers are investigated. We perform very long simulations on 8963grids accelerated by luminosity boost factors of 1000, 3162 and 10,000. In these simulations, the growing penetrative convection reduces the initially unrealistically large entrainment. This reduction is enabled by a spatial separation that develops between the entropy gradient and the composition gradient. The convective boundary moves outward much more slowly at the end of these simulations. Finally, we present a 1D method to predict the extent and character of penetrative convection beyond the Schwarzschild boundary. The 1D model is based on a spherically averaged reduced entropy equation that takes the turbulent dissipation as input from the 3D hydrodynamic simulation and takes buoyancy and all other energy sources and sinks into account. This 1D method is intended to be ultimately deployed in 1D stellar evolution calculations and is based on the properties of penetrative convection in our simulations carried forward through the local thermal timescale.  more » « less
Award ID(s):
2309101 2032010 1814181
PAR ID:
10556493
Author(s) / Creator(s):
; ; ; ; ; ;
Publisher / Repository:
The Astrophysical Journal
Date Published:
Journal Name:
The Astrophysical Journal
Volume:
975
Issue:
2
ISSN:
0004-637X
Page Range / eLocation ID:
271
Subject(s) / Keyword(s):
convection, massive stars, internal gravity waves, mixing length theory, stellar hydrodynamics, convective boundary mixing
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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