Angular momentum transport in a contracting stellar radiative zone embedded in a large-scale magnetic field

Context. Some contracting or expanding stars are thought to host a large-scale magnetic field in their radiative interior. By interacting with the contraction-induced flows, such fields may significantly alter rotational history of star. They thus constitute promising way address problem angular momentum transport during rapid phases stellar evolution. Aims. In this work, we aim study interplay between flows and zone. Methods. We performed axisymmetric Boussinesq anelastic numerical simulations which portion zone was modelled by rotating spherical layer, stably stratified embedded (either dipolar quadrupolar) field. This layer is subject mass-conserving radial velocity mimicking contraction. The quasi-steady were studied strongly weakly regimes relevant for pre-main sequence cores subgiant red giant stars. parametric consists varying amplitude contraction initial other parameters fixed guidance previous study. Results. After an unsteady phase toroidal grew linearly then back-reacted on flow, configuration reached, characterised presence two magnetically decoupled regions. one them, tension imposes solid-body rotation. other, called dead zone, main force balance equation does not involve Lorentz differential rotation exists. regime, when quadrupolar, magnetorotational instability found develop zones. structure eventually destroyed able build up whole observed our simulations, but argue that it be present Conclusions. propose scenario account post-main evolution solar-like stars, quasi-solid can maintained timescale. Then, would destroy enables set in. Such contraction-driven could also at origin dichotomy intermediate-mass