MEASUREMENTS OF FLOW SPEEDS IN THE CORONA BETWEEN 2-R-CIRCLE-DOT AND 30-R-CIRCLE-DOT

Time-lapse sequences of white-light images, obtained during sunspot mi nimum conditions in 1996 by the Large Angle Spectrometric Coronagraph on the Solar and Heliospheric Observatory, give the impression of a co ntinuous outflow of material in the streamer belt, as if we were obser ving Thomson scattering from inhomogeneities in the solar wind. Pursui ng this idea, we have tracked the birth and outflow of 50-100 of the m ost prominent moving coronal features and find that: 1. They originate about 3-4 R. from Sun center as radially elongated structures above t he cusps of helmet streamers. Their initial sizes are about 1 R. in th e radial direction and 0.1 R. in the transverse direction. 2. They mov e radially outward, maintaining constant angular spans and increasing their lengths in rough accord with their speeds, which typically doubl e from 150 km s(-1) near 5 R. to 300 km s(-1) near 25 R.. 3. Their ind ividual speed profiles upsilon(tau) cluster around a nearly parabolic path characterized by a constant acceleration of about 4 m s(-2) throu gh most of the 30 R. field of view. This profile is consistent with an isothermal solar wind expansion at a temperature of about 1.1 MK and a sonic point near 5 R.. Based on their relatively small initial sizes , low intensities, radial motions, slow but increasing speeds, and loc ation in the streamer belt, we conclude that these moving features an passively tracing the outflow of the slow solar wind.