Contributed Talk - Splinter Stars

Tuesday, 14 September 2021, 09:40   (virtual Stars)

The processes driving jets during the formation of high-mass stars

G. André Oliva, Rolf Kuiper
Universität Tübingen, Universität Heidelberg

During the formation of high-mass stars, jets and other magnetically-driven outflows provide linear and angular momentum back to their environment, and constitute a probe into the early stages of their formation. We investigate the formation of high-mass stars starting from the collapse of a rotating magnetized cloud, and the subsequent formation of a system composed by a centrifugally-supported accretion disk and magnetically-driven outflows embedded in the infalling proto-stellar envelope. For this purpose, we ran numerical simulations with resistive MHD, self-gravity and radiation transport on grids with high resolution as it has never been achieved before in the context of massive star formation: we reach sub-au scales close to the forming massive star, which allow us to resolve the launching region of the jet. We identify the several physical processes involved in the launching, acceleration, propagation and termination of the outflows, and find a fast, collimated, magneto-centrifugally launched jet, and a wide-angle tower flow driven by magnetic pressure. A cavity wall develops in the boundary between infall and the jet, and contributes episodically to both processes. In the long-term, magnetic braking creates a region in the proximity of the protostar where the angular momentum loss transforms the rotation of the disk into infall, with replenishment of material coming from the cavity wall. At this point, the magneto-centrifugal mechanism is disrupted, but not the outflows driven by magnetic pressure. We also investigate the variation of the properties of the outflows with the initial mass of the cloud, its density profile, and the initial magnetic field configurations.