The efficiency of mixed modes for angular momentum transport

Core rotation rates of red-giant stars inferred from asteroseismic observations are substantially lower than predicted by current stellar models. This indicates the lack of a mechanism capable of efficiently transporting angular momentum (AM) in radiative interiors. Mixed pressure-gravity modes are a promising candidate as they have been shown to efficiently extract AM from the core of evolved red giants. We developed a post-processing code to compute AM transport by mixed modes and its interplay with the meridional circulation. This code uses MESA stellar evolution models as input. We find a spin down of evolved red giants' cores as a result of mixed modes and show their effect on the rotation profile as a function of evolution. Finally, we compare the computed core and surface rotation rates with asteroseismic observations.