V. G. Fainshtein, Ya. I. Egorov
The joint use of high-resolution data from PROBA2 and SDO satellites and LASCO/SOHO coronographs enabled us to examine early stages of initiation and propagation of six limb CMEs registered in June 2010 - June 2011. For five events under consideration, the CME initiation is marked by filament (prominence) eruption or by a loop-like structure having another nature. Subsequently, several loop-like structures having higher brightness and following each other at different velocities appear in the region of the CME initiation. The CME frontal structure is formed by these loop-like structures. The time-dependent velocities and acceleration of the ejection front have been obtained for all CMEs under consideration. We have drawn a conclusion about the possible existence of two CME types dependent on the time profile of their velocity. The first CME type comprises the ejections whose velocity decreases abruptly by more than 100 km/s after having reached the maximum; it thereupon passes to slow deceleration/variation. The second CME type is formed by the ejections whose velocity varies insignificantly after reaching the maximum. The CME angular size is shown to increase up to threefold at the initial stage of propagation; it increases twofold 3.5-11 minutes after the first measurement of this parameter. When considering 3 CMEs, we see that their broadening exceeds their extension in the longitudinal direction during a certain period of time at the initial propagation stage.
View original:
http://arxiv.org/abs/1208.2071
No comments:
Post a Comment