Long-term variations of the flow direction and angular momentum of the solar wind observed by Hellos

The flow directions of solar wind protons were measured in situ by the Hell os spacecraft. A long-term average of the velocity shows a systematic drift in the latitudinal flow angle of about +1 degrees north observed with Hell os 1 and -1 degrees south observed onboard of Hellos 2. The longitudinal Ro w angle miff rates about +1 degrees west over a period of almost 10 years f or Hellos 1 and 6 years for Hellos 2. This systematic change with time of t he plasma flow direction may be caused by solar-cycle variations of the ori entation of the Sun's magnetic field which partially corotates with the Sun inside the Alfven surface (varying in distance between 10 R. over the pole s and 30 R. near the equator). These variations must have been imprinted on the solar wind flow when it detached from corotation with the Sun near the Alfven point. The angular momentum of the wind is intimately connected wit h the flow and field directions. The gain of total angular momentum of the wind equals the loss of angular momentum of the Sun, which is caused by the torque exerted on the rotating Sun through the magnetic field of the expan ding corona. Implications of the Hellos observations for models of the magn etic fields of the Sun as well as the solar wind are discussed. We show evi dence, that changes of the solar magnetic field inside the Alfven surface a re responsible for systematic drifts in the solar wind flow direction.