Impact of different approaches to computing rotating stellar models

Abstract

Context. The physics of stellar rotation plays a crucial role in the evolution of stars, in their final fates, and for the properties of compact remnants. Aims. Diverse approaches have been adopted to incorporate the effects of rotation in stellar evolution models. This study seeks to explore the consequences that these various prescriptions for rotation have for the essential outputs of massive star models. Methods. We computed a grid of 15 and 60 M⊙ stellar evolution models with the Geneva Stellar Evolution Code that accounted for both hydrodynamical and magnetic instabilities induced by rotation. Results. In the 15 and 60 M⊙ models, the choice of the vertical and horizontal diffusion coefficients for the nonmagnetic models strongly impacts the evolution of the chemical structure, but has a weak impact on the angular momentum transport and the rotational velocity of the core. In the 15 M⊙ models, the choice of the diffusion coefficient impacts the convective core size during the core H-burning phase, regardless of whether the model begins core He-burning as a blue or red supergiant and regardless of the core mass at the end of He-burning. In the 60 M⊙ models, the evolution is dominated by mass loss and is less strongly affected by the choice of the diffusion coefficient. In the magnetic models, magnetic instability dominates the angular momentum transport, and these models are found to be less strongly mixed than their rotating nonmagnetic counterparts. Conclusions. Stellar models with the same initial mass, chemical composition, and rotation may exhibit diverse characteristics depending on the physics applied. By conducting thorough comparisons with observational features, we can ascertain which method(s) produce the most accurate results in different cases.