A Statistical Study of the CME Properties Based on Angular Width during the Solar Cycle 24

Abstract

The present work is carried out in order to analyze the data for more than 15 000 coronal mass ejections (CMEs) during solar cycle 24, spanning the period of 2009–2017. We investigated, the properties of two categories of CMEs, narrow (W ≤ 20°) and normal (W > 20°), including angular width, linear speed, acceleration and their location. Based on statistical analysis, it is found the following. (1) 45% of the CMEs found in the angular range of W ∼ 10° and 30° with peak at 15°. (2) 70% of the narrow and 60% normal CMEs speed lies in the range of 150–400 km/s. The occurrence rate of both categories of CMEs declines sharply at linear speeds > 400 km/s and 0.1% narrow while 1.95% are of normal category, having the speeds above than 1000 km/s. (3) The 99% of narrow and 82% of normal CMEs are biased towards deceleration whereas small portion of normal CMEs do move with positive acceleration. We observed a low correlation between linear speed and acceleration –0.13 and –0.24 for narrow and normal CMEs respectively. (4) The latitudinal distribution of almost all narrow and normal CMEs were observed from equatorial regions during solar minimum, while during solar maximum, the distribution becomes wider and appears at all latitudes for both catagories. Despite of the fact that, solar cycle 24 is a weaker one in terms of geoeffectivity, but we observe a greater number of CMEs than solar cycle 23 throughout the solar maximum.