Radio Astronomy Centre, Tata Institute of Fundamental Research, Udhagamandalam (Ooty), India

We report the results of our investigation of interplanetary effects caused by the large solar flare (X5.7/3B) that occurred on July 14, 2000. In association with this event a bright, fast, halo coronal mass ejection (CME) was observed. The on-disk signatures of the initiation of the CME at low-coronal heights, £ 2 R_E, are based on the multi-wavelength, high-cadence images obtained from the Nançay Radioheliograph. The expansion of the CME inferred from the radio data indicate a nearly developed halo at the low corona. The white-light images and CME follow up measurements in the interplanetary medium also show, in agreement with the radio data, the propagation of the fully developed halo CME. The inference on the consequences of the CME in the inner heliosphere is from the interplanetary scintillation observations obtained with the Ooty Radio Telescope and multi-antenna system at the Solar-Terrestrial Environment Laboratory. Scintillation measurements at Ooty on a grid of a large number of radio sources provide an opportunity to image the disturbance associated with the CME at different distances from the Sun before its arrival at the near-Earth space. The evolution of speed of the CME in the inner heliosphere has been studied. The speed estimates indicate a two-level deceleration, low and rapid decline of speed at distances, respectively, within or about 100 solar radii and at larger distances from the Sun. We also briefly discuss the increase in size of the CME with distance. The expansion of the CME, formation of the halo in the low corona, and its speed history in the interplanetary medium suggest a driving energy, which is likely supplied by the twisted magnetic flux rope system associated with the CME.

accepted, Ap. J., 2001