Schwarzschild and Ledoux are Equivalent on Evolutionary Timescales

Evan H. Anders*, Adam S. Jermyn, Daniel Lecoanet, Adrian E. Fraser, Imogen G. Cresswell, Meridith Joyce, J. R. Fuentes

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


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 languageEnglish (US)
Article numberL10
JournalAstrophysical Journal Letters
Issue number1
StatePublished - Mar 1 2022

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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