Measurements of angular momentum in jets and outflows, and feedback on the disk

The problem of understanding how a newly forming solar system manages to lose angular momentum from the stage of collapsing core to the final main sequence phase is a long-standing one. This is especially pertinent regarding the evolution of the accretion disks. Both theoretical studies and recent observational surveys have questioned the paradigm of viscosity-driven disk evolution, while at the same time alternative scenarios considering the action of magnetically driven winds have gained credit. In recent years, observers have struggled to provide constraints to establish which mechanism is principally responsible, and one of the most interesting findings proved to be the detection and characterisation of rotational motions in the wind components, coupled with the rotation signatures in the associated disk. Such results allowed the estimate of the angular momentum transported by the winds and confirmed the validity of the magneto-hydrodynamic models for the acceleration of outflows and simultaneous disk braking. Importantly, the rotation estimates proved to allow the derivation of the region of origin of the winds in the disk (‘footpoint’), thus enabling a direct evaluation of the feedback of the outflows on the disk in the planet formation region. Here we present an overview on the observational efforts in this direction, from the first detection of jet rotation with the Hubble Space Telescope, to the current state of play, in which ALMA is providing the most stringent constraints to both wind models and related disk evolution. Finally, we mention the future observational directions to further explore this intriguing topic.