A semi-empirical model for magnetic braking of solar-type stars

Leila Sadeghi Ardestani, Tristan Guillot, Pierre Morel

Published 2017-09-10Version 1

We develop new angular momentum evolution models for stars with masses of $0.5$ to $1.6~\rm M_\odot$ and from the pre-main-sequence (\rm PMS) through the end of their main-sequence (\rm MS) lifetime. The parametric models include magnetic braking based on numerical simulations of magnetised stellar winds, mass loss rate prescription, core-envelope decoupling as well as disk locking phenomena. We have also accounted for recent developments in modelling dramatically weakened magnetic braking in stars more evolved than the Sun. We fit the free parameters in our model by comparing model predictions to rotational distributions of a number of stellar clusters as well as individual field stars. Our model reasonably successfully reproduces the rotational behaviour of stars during the \rm PMS phase to the zero-age main-sequence (\rm ZAMS) spin up, sudden \rm ZAMS spin down, and convergence of the rotation rates afterwards. We find that including core-envelope decoupling improves our models especially for low-mass stars at younger ages. In addition, by accounting for the almost complete suppression of magnetic braking at slow spin periods, we provide better fits to observations of stellar rotations compared to previous models.