Simultaneous LASCO/1998-Eclipse Observations Of A Large-Scale Polar Event

TitreSimultaneous LASCO/1998-Eclipse Observations Of A Large-Scale Polar Event
Type de publicationConference Paper
Year of Publication1999
AuteursZhukov, A., Koutchmy S., Lamy P., DelaboudinièRe J.-P., Delannée C., Bocchialini K., Guisard S., Filippov B., and Veselovsky I.
ÉditeurVial, J.-C., and Kaldeich-Schü B.
Conference Name8th SOHO Workshop: Plasma Dynamics and Diagnostics in the Solar Transition Region and Corona
Date PublishedOct

A relatively faint but large scale polar region event was observed in Aug. 1996 by Boulade et al. 1998 (SoHO SP 404, 217); we first reconsider this event which has been related to a high latitude filament disappearance. We continue the study of this class of events by analyzing the large scale restructuring which occurred above the N-Pole region at the time of the last Feb. 26, 1998 total solar eclipse. Well calibrated WL-eclipse images are used to provide the absolute values of electron densities of the quasi-radial structure appearing at the feet of the event. This structure can also be considered as a type of abnormally broad and curved polar plume, a type of activity already reported in the literature. Unfortunately, the examination of sequences of EIT images taken at that time seems to indicate that the roots of the structure are on the back side of the Sun. However the most impressive effects are seen in the high polar region, at several radii, based on the analysis of processed Lasco-C2 difference images. Large proper motions are deduced over density structures. Both these events confirm that polar regions are indeed showing a new class of CME activity (possibly related to the Hewish's CMEs), which is seen inside coronal holes. A whole set of interesting questions is then appearing to understand the occurrence of a polar CME propagating in the heart of a large unipolar magnetic region of the corona.