In section 7. Stellar structure and evolution
The brightness of the red giant branch tip. Theoretical framework, a set of reference models, and predicted observables
>>> The brightness of the tip of the red giant branch is a useful reference quantity for several fields of astrophysics, and thus a theoretical model that accurately predicts its properties is important. This paper provides a solid theoretical model, valid for a reference set of standard physical assumptions, that is mostly independent of numerical details. The paper examines the dependence of the brightness of the tip of the red giant branch on physical assumptions and numerical details for a wide range of metallicities and masses based on two different stellar evolution codes. The authors present a reference set of models based on the most up to date physical inputs in infrared colours suitable for interpreting observations of resolved stellar populations. Also included are analytic fits to facilitate their use. This paper demonstrates that careful stellar modelling allows an accurate prediction of the luminosity of the red giant branch tip. Differences from empirically determined brightnesses may result either from inaccurate colour transformations or from deficits in the constitutional physics. The best-tested theoretical reference values are presented.