Modelling of a CME-driven Shock Detected by UVCS/SoHO on March 3, 2000
Abstract
We report the observation of a 1100 km/s CME-driven shock with the UltraViolet Coronagraph Spectrometer (UVCS) telescope operating on board SoHO on March 3, 2000. The CME was observed by the Large Angle Spectroscopic Coronagraph (LASCO), and the radio signature of the shock was detected by the Hiraiso and Culgoora radio spectrographs as an intense type II radio burst. We derived the density profile just before the passage of the shock from UVCS observations and obtained a reliable estimate of the shock speed from the type II radio burst drift rate. The spectral profiles of both the O VI and Lyman alpha lines were Doppler dimmed at the passage of the shock and showed broad wings caused by the emission from shocked material along the line of sight. By estimating a compression ratio of 1.8 from the observed splitting of the radio emission bands in the spectrographs and assuming perpendicular propagation of the shock we derive a magnetic field strength of 1 Gauss at 1.8 solar radii and an Alfvenic Mach number of 1.7. The observed line broadening for both the protons and the Oxygen ions was modeled by adopting a mechanism in which the heating is due to the nondeflection of the ions at the shock ramp.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2001
- Bibcode:
- 2001AGUFMSH21B..05M
- Keywords:
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- 7509 Corona;
- 7513 Coronal mass ejections;
- 7534 Radio emissions;
- 7549 Ultraviolet emissions;
- 7851 Shock waves