A study of convective core overshooting as a function of stellar mass based on two-dimensional hydrodynamical simulations

Abstract

We perform two-dimensional numerical simulations of core convection for zero-age-main-sequence stars covering a mass range from 3 $M_{\odot }$ to 20 $M_{\odot }$. The simulations are performed with the fully compressible time-implicit code MUSIC. We study the efficiency of overshooting, which describes the ballistic process of convective flows crossing a convective boundary, as a function of stellar mass and luminosity. We also study the impact of artificially increasing the stellar luminosity for 3 $M_{\odot }$ models. The simulations cover hundreds to thousands of convective turnover timescales. Applying the framework of extreme plume events previously developed for convective envelopes, we derive overshooting lengths as a function of stellar masses. We find that the overshooting distance ($d_{\mathrm{ov}}$) scales with the stellar luminosity ($L$) and the convective core radius ($r_{\mathrm{conv}}$). We derive a scaling law $d_{\mathrm{ov}}\propto L^{1/3}{r}_{\mathrm{conv}}^{1/2}$ which is implemented in a 1D stellar evolution code and the resulting stellar models are compared to observations. The scaling predicts values for the overshooting distance that significantly increase with stellar mass, in qualitative agreement with observations. Quantitatively, however, the predicted values are underestimated for masses $\gtrsim 10M_{\odot }$. Our 2D simulations show the formation of a nearly-adiabatic layer just above the Schwarzschild boundary of the convective core, as exhibited in recent 3D simulations of convection. The most luminous models show a growth in size with time of the nearly-adiabatic layer. This growth seems to slow down as the upper edge of the nearly-adiabatic layer gets closer to the maximum overshooting length and as the simulation time exceeds the typical thermal diffusive timescale in the overshooting layer.

13 pages, accepted for publication in MNRAS

References in corpus (17)

• Modules for Experiments in Stellar Astrophysics (MESA)
• The spectroscopic Hertzsprung-Russell diagram of Galactic massive stars
• Three-Dimensional Simulations of Massive Stars: I. Wave Generation and Propagation
• The dependence of convective core overshooting on stellar mass: reality check, and additional evidence
• Numerical Simulations of Penetration and Overshoot in the Sun
• Fully compressible simulations of waves and core convection in main-sequence stars
• Convective core entrainment in 1D main sequence stellar models
• Solar overshoot region and small-scale dynamo with realistic energy flux
• Dependence of Convective Boundary Mixing on Boundary Properties and Turbulence Strength
• Extreme value statistics for two-dimensional convective penetration in a pre-Main Sequence star
• Stellar convective penetration: parameterized theory and dynamical simulations
• Calibrating Core Overshooting Parameters With Two-dimensional Hydrodynamical Simulations
• Benchmarking the Multi-dimensional Stellar Implicit Code MUSIC
• Spherical-shell boundaries for two-dimensional compressible convection in a star
• Apsidal motion in the massive binary HD152218
• Two-dimensional simulations of solar-like models with artificially enhanced luminosity -- I. Impact on convective penetration
• Apsidal motion in massive eccentric binaries in NGC 6231: The case of HD 152219

Cited by in corpus (22)

• Convective boundary mixing in main-sequence stars: theory and empirical constraints
• The photometric variability of massive stars due to gravity waves excited by core convection
• 3D stellar evolution: hydrodynamic simulations of a complete burning phase in a massive star
• The impact of convective criteria on the properties of massive stars
• Two-dimensional simulations of internal gravity waves in a 5 $M_{\odot }$ Zero-Age-Main-Sequence model
• Multidimensional Simulations of Core Convection
• Gaia BH1 and BH2 -- evolutionary models with overshooting of the black hole progenitors within the present-day binary separation
• Evolution of rotating massive stars adopting a newer, self-consistent wind prescription at SMC metallicity
• The EBLM Project XII. An eccentric, long-period eclipsing binary with a companion near the hydrogen-burning limit
• Magnetohydrodynamic simulations of A-type stars: Long-term evolution of core dynamo cycles
• Turbulent dynamo action and its effects on the mixing at the convective boundary of an idealized oxygen-burning shell
• Convective shells in the interior of Cepheid variable stars: overshooting models based on hydrodynamic simulations
• In search of gravity mode signatures in main sequence solar-type stars observed by Kepler
• Penetrative magneto-convection of a rotating Boussinesq flow in $f$-planes
• The theoretical pulsation spectra of hot B subdwarfs. Static and evolutionary STELUM models
• The shape of convection in 2D and 3D global simulations of stellar interiors
• Chemical evolution of close massive binaries -- tidally-enhanced or tidally-suppressed mixing?
• Mixing by Internal Gravity Waves in Stars: Assessing Numerical Simulations Against Theory
• Effects of stratification on overshooting and waves atop the convective core of $5M_{\odot }$ main-sequence stars
• Evolution of stars with 60 and 200 Msun: predictions for WNh stars in the Milky Way
• Spectral Difference method with a posteriori limiting: II- Application to low Mach number flows
• Internally heated and fully compressible convection: flow morphology and scaling laws