Convective core entrainment in 1D main-sequence stellar models
Document Type
Article
Publication Date
5-1-2021
Abstract
3D hydrodynamics models of deep stellar convection exhibit turbulent entrainment at the convective-radiative boundary which follows the entrainment law, varying with boundary penetrability. We implement the entrainment law in the 1D Geneva stellar evolution code. We then calculate models between 1.5 and 60 M-circle dot at solar metallicity (Z = 0.014) and compare them to previous generations of models and observations on the main sequence. The boundary penetrability, quantified by the bulk Richardson number, Ri(B), varies with mass and to a smaller extent with time. The variation of Ri(B) with mass is due to the mass dependence of typical convective velocities in the core and hence the luminosity of the star. The chemical gradient above the convective core dominates the variation of Ri(B) with time. An entrainment law method can therefore explain the apparent mass dependence of convective boundary mixing through Ri(B). New models including entrainment can better reproduce the mass dependence of the main-sequence width using entrainment law parameters A similar to 2 x 10(-4) and n = 1. We compare these empirically constrained values to the results of 3D hydrodynamics simulations and discuss implications.
Keywords
Convection, Turbulence, Stars: Evolution, Stars: Hertzsprung-Russell and colour-magnitude diagrams, Interiors
Divisions
PHYSICS
Funders
European Union FP7 European Research Council (ERC) [Grant No: 306901],World Premier International Research Centre Initiative (WPI Initiative),Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT),IReNA Accel Net Network of Networks,National Science Foundation (NSF) [Grant No: OISE-1927130],European Cooperation in Science and Technology (COST) [Grant No: CA16117],ERC Horizon 2020 research and innovation programme [Grant No: 833925],Department for Business, energy and Industrial Strategy (BEIS) capital funding via STFC [Grant No: ST/P002293/1 & ST/R002371/1],Durham University,UK Research & Innovation (UKRI) Science & Technology Facilities Council (STFC) [Grant No: ST/R000832/1],Department for Business, Innovation and Skills (BIS) National E Infrastructure capital grant [Grant No: ST/K00042X/1],UK Research & Innovation (UKRI) Science & Technology Facilities Council (STFC) [Grant No: ST/H008519/1 & ST/K00087X/1 & ST/K003267/1]
Publication Title
Monthly Notices of the Royal Astronomical Society
Volume
503
Issue
3
Publisher
Oxford University Press
Publisher Location
GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND