A Comparison of the Initial Speed of Coronal Mass Ejections with the Magnetic Flux and Magnetic Helicity of Magnetic Clouds

Abstract

To investigate the relationship between the speed of a coronal mass ejection (CME) and the magnetic energy released during its eruption, we have compared the initial speed of CMEs (V _CME) and the two parameters of their associated magnetic clouds (MC), magnetic flux (F _MC), and magnetic helicity per unit length (|H _MC|/L), for 34 pairs of CMEs and MCs. The values of these parameters in each MC have been determined by fitting the magnetic data of the MC to the linear force-free cylindrical model. As a result, we found that there are positive correlations between V ² _CME and F _MC, and between V ² _CME and |H _MC|/L. It is also found that the kinetic energy of CMEs (E _CME) is correlated with F _MC and |H _MC|/L of the associated MC. In contrast, we found no significant correlation between langV _MCrang² and F _MC, nor between langV _MCrang² and |H _MC|/L. Our results support the notion that the eruption of a CME is related to the magnetic helicity of the source active region.