The Challenge of Sub-Keplerian Rotation for Disk Winds
  Strong magnetization makes the disks surrounding young stellar objects rotate at rates that are too sub-Keplerian to enable the thermal launching of disk winds from their surfaces unless the rate of gas diffusion across field lines is dynamically fast. This under-appreciated implication of disk magnetization poses a considerable challenge for disk-wind theory. 
Frank H. Shu, Susana Lizano, Daniele Galli, Mike J. Cai, Subhanjoy   Mohanty