Investigations of slow and fast Coronal Mass Ejections and their associated activities in Solar Cycle 24

Abstract

Intensive flare (>M5.0 X-ray class) associated Coronal Mass Ejections (CMEs), during 2008- 2013 in solar cycle 24, are separated into two groups based on CME speed.  Group-I contains 31 CME events with speed below 900 km/s and Group-II contains 27 CME events with speed above 900 km/s.    (i) The mean CME speeds of Groups I and II are found to be  558 km/s and 1629 km/s, and the mean CME width of the Group-II  is slightly higher than the Group-I.  The CMEs of Group-II are highly decelerated than the CMEs of Group-I. (ii) The rise time and duration of intensive flares of Group-II is slightly greater than those of Group-I. (iii) While 60% of Group-I events are located on the southern hemisphere, 85% of Group-II events are located on the northern hemisphere. (iv) The number of Halos, DH type IIs, SEP events associated with Group-II are respectively 2, 3 and 6 times that of Group-I. (v) Utilizing the density models of suitably connecting the corona and interplanetary medium, the shock formation height of DH type radio bursts are found to be in the height range 2- 6 Rs and the maximum estimated distance of shock are found to be in the height range 16 -215 Rs. (vi) The mean shock speed of Group I and Group II events (599 km/s and 1359 km/s) are in agreement with the CME speed.