Abstract
Stellar evolution models calculate convective boundaries using either the Schwarzschild or Ledoux criterion, but confusion remains regarding which criterion to use. Here we present a 3D hydrodynamical simulation of a convection zone and adjacent radiative zone, including both thermal and compositional buoyancy forces. As expected, regions that are unstable according to the Ledoux criterion are convective. Initially, the radiative zone adjacent to the convection zone is Schwarzschild unstable but Ledoux stable due to a composition gradient. Over many convective overturn timescales, the convection zone grows via entrainment. The convection zone saturates at the size originally predicted by the Schwarzschild criterion, although in this final state the Schwarzschild and Ledoux criteria agree. Therefore, the Schwarzschild criterion should be used to determine the size of stellar convection zones, except possibly during short-lived evolutionary stages in which entrainment persists.
| Original language | English (US) |
|---|---|
| Article number | L10 |
| Journal | Astrophysical Journal Letters |
| Volume | 928 |
| Issue number | 1 |
| DOIs | |
| State | Published - Mar 1 2022 |
Funding
We thank Anne Thoul, Dominic Bowman, Jared Goldberg, Tim Cunningham, Falk Herwig, and Kyle Augustson for useful discussions, which helped improve our understanding. We thank the anonymous referee for constructive feedback, which improved the clarity of this manuscript. E.H.A. is funded as a CIERA Postdoctoral fellow and would like to thank CIERA and Northwestern University. The Flatiron Institute is supported by the Simons Foundation. D.L. and I.G.C. are supported in part by NASA HTMS grant 80NSSC20K1280. A.E.F. acknowledges support from NSF grant Nos. AST-1814327 and AST-1908338. I.G.C. acknowledges the support of the University of Colorados George Ellery Hale Graduate Student Fellowship. M.J. acknowledges support from the Barry M. Lasker Data Science Fellowship awarded by the Space Telescope Science Institute. J.R.F. acknowledges support from a McGill Space Institute (MSI) Fellowship. This research was supported in part by the National Science Foundation under grant No. PHY-1748958, and we acknowledge the hospitality of KITP during the Probes of Transport in Stars Program. Computations were conducted with support from the NASA High End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center on Pleiades with allocation GID s2276.
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science