Journal
ASTROPHYSICAL JOURNAL
Volume 926, Issue 2, Pages -Publisher
IOP Publishing Ltd
DOI: 10.3847/1538-4357/ac408d
Keywords
-
Categories
Funding
- NASA HTMS [80NSSC20K1280]
- NASA SSW [80NSSC19K0026]
- NASA High End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center on Pleiades [GID s2276]
- Simons Foundation
Ask authors/readers for more resources
Most stars have convection zones, but the behavior of convective boundaries is not well understood. In this study, researchers conducted 3D numerical simulations and discovered the existence of penetration zones. By defining the penetration parameter P and constructing an energy-based theoretical model, they successfully described the simulations. This study is important for understanding convective phenomena in stars.
Most stars host convection zones in which heat is transported directly by fluid motion, but the behavior of convective boundaries is not well-understood. Here, we present 3D numerical simulations that exhibit penetration zones: regions where the entire luminosity could be carried by radiation, but where the temperature gradient is approximately adiabatic and convection is present. To parameterize this effect, we define the penetration parameter P, which compares how far the radiative gradient deviates from the adiabatic gradient on either side of the Schwarzschild convective boundary. Following Roxburgh and Zahn, we construct an energy-based theoretical model in which P controls the extent of penetration. We test this theory using 3D numerical simulations that employ a simplified Boussinesq model of stellar convection. The convection is driven by internal heating, and we use a height-dependent radiative conductivity. This allows us to separately specify . and the stiffness. of the radiative-convective boundary. We find significant convective penetration in all simulations. Our simple theory describes the simulations well. Penetration zones can take thousands of overturn times to develop, so long simulations or accelerated evolutionary techniques are required. In stars, we expect P approximate to 1, and in this regime, our results suggest that convection zones may extend beyond the Schwarzschild boundary by up to similar to 20%-30% of a mixing length. We present a MESA stellar model of the Sun that employs our parameterization of convective penetration as a proof of concept. Finally, we discuss prospects for extending these results to more realistic stellar contexts.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available