LASCO OBSERVATIONS OF DISCONNECTED MAGNETIC-STRUCTURES OUT TO BEYOND 28 SOLAR RADII DURING CORONAL MASS EJECTIONS

Two coronal mass ejections have been well observed by the LASCO corona graphs to move out into the interplanetary medium as disconnected plas moids. The first, on July 28, 1996, left the Sun above the west limb a round 18:00 UT. As it moved out, a bright V shaped structure was visib le in the C2 coronagraph which moved into the field-of-view of C3 and could be observed out to beyond 28 solar radii. The derived average ve locity in the plane of the sky was 110 +/- 5 km s(-1) out to 5 solar r adii, and above 15 solar radii the velocity was 269 +/- 10 km s(-1). T hus there is evidence of some acceleration around 6 solar radii. The s econd event occurred on November 5, 1996 and left the west limb around 04:00 UT. The event had an average velocity in the plane of the sky o f similar to 511 km s(-1) below 4 R-., and it accelerated rapidly arou nd 5 R-. up to 310 +/- 10 km s(-1). In both events the rising plasmoid is connected back to the Sun by a straight, bright ray, which is prob ably a signature of a neutral sheet. In the November event there is ev idence for multiple plasmoid ejections. The acceleration of the plasmo ids around a projected altitude of 5 solar radii is probably a manifes tation of the source surface of the solar wind.