POYNTING JETS AND MHD WINDS FROM RAPIDLY ROTATING MAGNETIZED STARS

摘要

We discuss results of axisymmetic magnetohydrodynamic theory and sim-ulations of the interaction of a rapidly-rotating, aligned magnetized star withan accretion disk. The disk is considered to have a finite viscosity and magneticdiffusivity. The main parameters of the system are the star's angular velocityand magnetic moment, and the disk's viscosity, magnetic diffusivity, and massaccretion rate. We focus on the "propeller" regime where the inner radius of thedisk is larger than the corotation radius. We have found two different types ofmagnetohydrodynamic flows: as a "weak" and "strong" propellers. The strongpropellers have a powerful MHD disk wind and a collimated magnetically domi-nated or Poynting flux outflow from the surface of the star. The weak propellershave only weak outflows. We discuss the time-averaged characteristics of theinteraction between the main elements of the system, the star, the disk, thewind from the disk, and the jet from the star. Rates of exchange of mass andangular momentum between the elements of the system are derived as a func-tion of the main parameters. These results are applicable to the early evolutionof classical T Tauri stars. They may be also used to explain the variation ofangular velocity of neutron stars and cataclysmic variables.