Investigations of slow and fast coronal mass ejections and their associated activities in Solar cycle 24

Abstract

<span style="font-size:11.0pt;font-family: " times="" new="" roman","serif";mso-fareast-font-family:"times="" roman";mso-bidi-font-family:="" mangal;mso-ansi-language:en-gb;mso-fareast-language:en-us;mso-bidi-language:="" hi"="" lang="EN-GB">The present papers compares the properties of slow and fast coronal mass ejections (CMEs) associated with intensive flare (>M5.0 X-ray class) during 2008-2013 in solar cycle 24. The CMEs are separated into two groups based on speed: Group I containing 31 CME events with speed below 900 km s^-1 and Group II containing 27 CME events with speed above 900 km s^-1. The mean CME speeds of Groups I and II are found to be 558 and 1629 km s^-1, respectively and the mean CME width of the Group II is slightly higher than Group I. The CMEs of Group II are highly decelerated than the CMEs of Group I. It is found that the rise time and duration of intensive flares of Group II is slightly greater than those of Group I. While 60% of Group I events are located on the southern hemisphere, 85% of Group II events are located on the northern hemisphere. Further, the number of halos, DH type IIs, Solar energetic particle (SEP) events associated with Group II are 2, 3 and 6 times, respectively that of Group I. 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 R_{<span style="font-size:11.0pt;font-family:" ms="" mincho";mso-bidi-font-family:"ms="" mincho";="" background:white;mso-ansi-language:en-gb;mso-fareast-language:en-us;mso-bidi-language:="" hi"="" lang="EN-US">⊙</span>}<span style="font-size:11.0pt;font-family:" times="" new="" roman","serif";="" mso-fareast-font-family:"times="" roman";mso-bidi-font-family:mangal;="" mso-ansi-language:en-gb;mso-fareast-language:en-us;mso-bidi-language:hi"="" lang="EN-GB"> and the maximum estimated distance of shock are found to be in the height range 16-215 R_{<span style="font-size:11.0pt;font-family:" ms="" mincho";mso-bidi-font-family:="" "ms="" mincho";background:white;mso-ansi-language:en-gb;mso-fareast-language:en-us;="" mso-bidi-language:hi"="" lang="EN-US">⊙</span>}<span style="font-size:11.0pt; font-family:" times="" new="" roman","serif";mso-fareast-font-family:"times="" roman";="" mso-bidi-font-family:mangal;mso-ansi-language:en-gb;mso-fareast-language:en-us;="" mso-bidi-language:hi"="" lang="EN-GB">. The mean shock speed of Group I and Group II events (599 and 1359 km s^-1, respectively) are in agreement with the CME speed. On comparison of slow and fast events, the faster events are found to be mostly decelerated, mostly associated with stronger storms, more number of DH type II bursts and SEPs.</span></span></span>