Authors: Manoharan PK, Tokumaru M, Pick M, Subramanian P, Ipavich FM, Schenk K, Kaiser ML, Lepping RP, Vourlidas A
Reference: ASTROPHYSICAL JOURNAL 559 (2): 1180-1189 Part 1 OCT 1 2001
We report the results of our investigation of interplanetary effects caused by the large solar flare (X5.7/3B) that occurred on 2000 July 14. In association with this event a bright, fast, halo coronal mass ejection (CME) was observed. The analysis of multiwavelength, high-cadence images obtained from the Radioheliograph shows the on-disk signatures of the initiation of the CME at low-coronal Nancay heights, less than or equal to2 R-circle dot. The formation of the CME inferred from the radio data indicates 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 (IPS) observations obtained with the Ooty Radio Telescope and multiantenna system at the Solar-Terrestrial Environment Laboratory. Scintillation measurements at Ooty on a grid of a large number of radio sources provided 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 scintillation data in particular also played a crucial role in understanding the radial evolution of the speed of the CME in the inner heliosphere. The "speed-distance" plot indicates a two-level deceleration : (1) a low decline in speed at distances within or about 100 solar radii and (2) a rapid decrease at larger distances from the Sun. The linear increase in the size of the CME with radial distance is also briefly discussed. 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.
Keywords: solar-terrestrial relations, corona, coronal mass ejections (CMEs), flares, magnetic fields, radio radiation