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Far UV Spectra of Fast Coronal Mass Ejections Associated with X-class Flares

J. C. Raymond·A. Ciaravella·D. Dobrzycka·L. Strachan·Y. -K. Ko·M. Uzzo·N. -E. Raouafi
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Abstract

The Ultraviolet Coronagraph Spectrometer (UVCS) aboard the {\it SOHO} satellite has observed very fast Coronal Mass Ejections (CMEs) associated with X-class flares. These events show spectral signatures different than those seen in most other CMEs in terms of very rapid disruption of the pre-CME streamer, very high Doppler shifts and high temperature plasma visible in the [Fe XVIII] emission line. This paper describes three very similar events on 21 April, 23 July and 24 August 2002 associated with X-class flares. We determine the physical parameters of the pre-CME streamers and discuss the geometrical and physical nature of the streamer blowouts. In the 21 April event, the hot plasma seen as [Fe XVIII] is not related to the structure seen in [Fe XXI] by SUMER at lower heights. It has the form of a rapidly expanding fan, quite likely a current sheet. In the August event, on the other hand, the [Fe XVIII] is probably a bubble of hot plasma formed by reconnection in the wake of the CME. C III emission from the July 23 flare is detected as stray light in the UVCS aperture. It precedes the hard X-ray brightening by about 2 minutes.

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J. C. Raymond, A. Ciaravella, D. Dobrzycka, L. Strachan, Y. -K. Ko, M. Uzzo, N. -E. Raouafi. 2003-08-04. Far UV Spectra of Fast Coronal Mass Ejections Associated with X-class Flares. https://doi.org/10.1086/378663

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