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The Behaviour of the Outer Solar Corona (3 R to 10 R) During a Large Solar Flare Observed from OSO-7 in White Light

Published online by Cambridge University Press:  25 May 2016

G. E. Brueckner*
Affiliation:
Naval Research Laboratory, Washington, D.C. 20375, U.S.A.

Abstract

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(Solar Phys.). A very bright coronal streamer was observed on December 13, 1971 by the Naval Research Laboratory's coronagraph on board of OSO-7. The next day, the streamer had changed it's brightness and configuration considerably. Three subsequent coronagraph images, taken on December 14 at 0407, 0418 and 0430 UT show a large plasma cloud moving outward from the Sun between 3 and 10 solar radii. They also show distinct smaller clouds moving outward with projected velocities between 950 and 1100 km s−1. Traced back in time to the lower solar corona, these clouds coincide with discrete type II radiobursts observed from Culgoora between 0241 and 0256 UT. Each single cloud shows it's signature in the radio recording between 100 and 20 MHz. The drift velocity of the radio bursts can be determined to be 1600 km s−1 using Newkirk's coronal streamer model. Assuming, that the plasma clouds are ejected from an active region 30° behind the east limb vertically, their true velocities close to the surface of the Sun would be approximately 1400 km s−1, which is in good agreement with the drift velocities determined from the type II bursts, considering all uncertainties. Therefore, the type II burst disturbance moves with the same velocity as the driving material.

Type
Part III Shock Waves and Plasma Ejection
Copyright
Copyright © Reidel 1974