A COMPARISON OF THE INITIAL SPEED OF CORONAL MASS EJECTIONS WITH THE MAGNETIC FLUX AND MAGNETIC HELICITY OF MAGNETIC CLOUDS

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 〈 V MC 〉 2 and F MC , nor between 〈 V MC 〉 2 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.