Waves in the proton cyclotron frequency range in the CME observed by wind on August 7-8,1996: Theory and data

As first discussed by Farrugia et al. (J. Geophys. Res., 103, 6543, 1998), coronal mass ejections (CMEs) may support the excitation of electromagnetic ion cyclotron waves (EICWs). The proton plasma beta, and the electron temperature and anisotropy in the front region (similar to5 hours, translating to similar to6x10(6) km) of the CME observed by WIND on August 7-8, 1996 favor this possible excitation. Supplementing these measured parameters by other data taken from a survey of CME properties observed by the ISEE 3 spacecraft (Gosling et al., J. Geophys. Res., 92, 8519, 1987), we solve the EICW dispersion relation numerically. We find short e-folding times of EICWs, of the order of 5 min, i.e., much less than the typical evolution time of these ejecta. We suggest that high resolution data will show enhanced power in the 0.5 Hz range. (C) 2001 COSPAR. Published by Elsevier Science Ltd. All rights reserved.