Characteristics of DH type II bursts, CMEs and flares with respect to the acceleration of CMEs
Abstract
A detailed investigation on DHtypeII radio bursts recorded in DecaHectometer (hereinafter DHtypeII) wavelength range and their associated CMEs observed during the year 19972008 is presented. The sample of 212 DHtypeII associated with CMEs are classified into three populations: (i) Group I (43 events): DHtypeII associated CMEs are accelerating in the LASCO field view ( a>15 m s^{2}); (ii) Group II (99 events): approximately constant velocity CMEs (15< a<15 m s^{2}) and (iii) Group III (70 events): represents decelerating CMEs ( a<15 m s^{2}). Our study consists of three steps: (i) statistical properties of DHtypeII bursts of Group I, II and III events; (ii) analysis of time lags between onsets of flares and CMEs associated with DHtypeII bursts and (iii) statistical properties of flares and CMEs of Group I, II and III events. We found statistically significant differences between the properties of DHtypeII bursts of Group I, II and III events. The significance ( P _{ a }) is found using the oneway ANOVAtest to examine the differences between means of groups. For example, there is significant difference in the duration ( P _{ a }=5%), ending frequency ( P _{ a }=4%) and bandwidth ( P _{ a }=4%). The accelerating and decelerating CMEs have more kinetic energy than the constant speed CMEs. There is a significant difference between the nose height of CMEs at the end time of DHtypeIIs ( P _{ a }≪1%). From the time delay analysis, we found: (i) there is no significant difference in the delay (flare start—DHtypeII start and flare peak—DHtypeII start); (ii) small differences in the time delay between the CME onset and DHtypeII start, delay between the flare start and CME onset times. However, there are high significant differences in: flare duration ( P _{ a }=1%), flare rise time ( P _{ a }=0.5%), flare decay time ( P _{ a }=5%) and CMEs speed ( P _{ a }≪1%) of Group I, II and III events. The general LASCO CMEs have lower width and speeds when compared to the DH CMEs. It seems there is a strong relation between the kinetic energy of CMEs and DHtypeII properties.
 Publication:

Astrophysics and Space Science
 Pub Date:
 January 2012
 DOI:
 10.1007/s1050901108174
 Bibcode:
 2012Ap&SS.337...47P
 Keywords:

 Sun;
 Coronal mass ejections;
 Solar flares;
 Type II bursts