Influence of direct URCA processes in a strong magnetic field on dynamics of collapsing star envelope

Direct URCA processes in a collapsing star envelope with a strong magnetic field are investigated. It is shown that in the toroidal magnetic field these processes can develope a torque which quickly unwinds an envelope. A general expression for a force density along the field direction is obtained. An influence of the neutrino unwinding effect on a dynamics of the collapsar envelope is discussed and numerically estimated.