Comparing the Features of Generation of CMEs Moving with Different Speed in the Field of View of the LASCO Coronagraphs

Аннотация

This study is aimed at finding an answer to the following question: are there any fundamental differences in the generation of coronal mass ejections (CMEs) with different speeds, especially low and high speeds, detected in the field of view of LASCO coronagraphs? Fast CMEs are conventionally understood as mass ejections with a linear projection velocity in LASCO field of view \({{V}_{{LIN}}}\) > 1500 km/s; slow CMEs are those with \({{V}_{{LIN}}}\) ≤ 600 km/s. CMEs with \({{V}_{{LIN}}}\) between 600 and 1500 km/s are referred to as mass ejections with intermediate speed. The results of the analysis are presented by the example of three halo-type CME events (fast, slow, and intermediate) with sources in the sunspot groups removed from the center of the solar disk by no more than 45°. For analysis, we used data from SDO/AIA telescopes and the SDO/HMI instrument, as well as the LASCO C2 and C3 coronagraphs. The properties of active regions in which CMEs with different speeds have occurred are compared. The morphological features of the formation of the selected mass ejections based on the observations in the extreme ultraviolet lines are compared with features of their kinematics. Using the data of vector measurements of the photospheric magnetic field with the SDO/HMI instrument over the regions of CME formation, the altitude distributions of the magnetic field are calculated in the nonlinear force-free approximation. The analysis of these distributions showed that before the onset of a CME-related flare, the rate of altitude variation in the magnetic field above the CME generation site is noticeably different for all selected events.