Interplanetary Gas. XV. Nonradial Plasma Motions from the Orientations of Ionic Comet Tails

Orientations of Type I comet tails show a dispersion apparently attributable to effects of waves and/or discontinuities in the interplanetary medium. The mean aximuthal plasma velocity is calculated with an improved analysis, and a value of about 9 km is derived, which confirms Brandt's result; in addition, the azimuthal velocity is found to increase with increasing geomagnetic activity. These results allow a computation of the total loss rate of angular momentum from the Sun, and an c-folding time of 3-4 X i0 years is found for a constant solar wind. The initial Sun could have had a much higher equatorial rotational velocity, in agreement with Kraft's results, if the flux of the solar wind has a comparable time scale.