Studies on some properties of coronal mass ejections based on angular width

Abstract

We investigated the properties of narrow CMEs (width ≤20°), intermediate CMEs (20° < width < 200°) and wide CMEs (width ≥ 200°) observed during 23rd (1996–1997) and 24th (2008–2009) solar cycle minima and compared their characteristics. We found 1099 narrow CMEs during 24th solar cycle and this is 15 times greater than 23rd solar cycle (75). On the other hand, the number of wide CMEs during 23rd cycle (26) is 6.5 times greater than 24th solar cycle (4) minimum. There is no remarkable difference between the number of intermediate CMEs of 23rd (489) and 24th (506) solar cycle minima. The interesting result is that the CMEs width distributions of the two minima are very different. The median and mean speeds of intermediate CMEs during 24th cycle (195 and 215 km s−1) are smaller than those (256 and 290 km s−1) during 23rd cycle. There is no significant difference in median and mean speeds of narrow and wide CMEs. During 23rd and 24th solar cycle minima we noted (i) 71% and 83% of narrow CMEs, (ii) 81% and 94% of intermediate CMEs and (iii) 46% and 50% of wide CMEs have speed < 400 km s−1, respectively. The maximum CME speeds observed during 23rd and 24th cycle are 1556 km s−1 (wide CME) and 1103 km s−1 (intermediate CME), respectively. We noticed that the speed of 24th solar cycle CMEs is smaller than 23rd solar cycle CMEs. The narrow CMEs are found to be distributed at low and high latitudes in 24th cycle, whereas in 23rd cycle, most of the narrow CMEs occurred around the equator.