The First 3D Simulations of Carbon Burning in a Massive Star

TL;DR

This paper presents the first 3D hydrodynamic simulations of turbulent convection during carbon burning in a massive star, revealing convective boundary mixing via turbulent entrainment and highlighting the need for improved models.

Contribution

It provides the first detailed 3D simulations of carbon burning in a massive star, demonstrating turbulent entrainment at convective boundaries and informing stellar evolution models.

Findings

Convective boundary mixing occurs via turbulent entrainment.

Boundary expansion and entrainment rates vary with boundary stiffness.

Results suggest the need for improved CBM prescriptions in 1D models.

Abstract

We present the first detailed three-dimensional hydrodynamic implicit large eddy simulations of turbulent convection for carbon burning. The simulations start with an initial radial profile mapped from a carbon burning shell within a 15 solar mass stellar evolution model. We considered 4 resolutions from 128^3 to 1024^3 zones. These simulations confirm that convective boundary mixing (CBM) occurs via turbulent entrainment as in the case of oxygen burning. The expansion of the boundary into the surrounding stable region and the entrainment rate are smaller at the bottom boundary because it is stiffer than the upper boundary. The results of this and similar studies call for improved CBM prescriptions in 1D stellar evolution models.