Relation between a Moreton Wave and an EIT Wave Observed on 1997 November 4

Abstract

We consider the relationship between two flare-associated waves, a chromospheric Moreton wave and a coronal EIT wave, based on an analysis of an X-class flare event in AR 8100 on 1997 November 4. A Moreton wave was observed in $$\mathrm{H}\alpha$$, $$\mathrm{H}\alpha {+} 0.8\,$$ $$Å$$, and $$\mathrm{H}\alpha-0.8\,$$ $$Å$$ with the Flare-Monitoring Telescope (FMT) at the Hida Observatory. An EIT wave was observed in EUV with the Extreme ultraviolet Imaging Telescope (EIT) on board SOHO. The propagation speeds of the Moreton wave and the EIT wave were approximately $$715 \,\mathrm{km} \,\mathrm{s}^{-1}$$ and $$202 \,\mathrm{km} \,\mathrm{s}^{-1}$$, respectively. The times of visibility for the Moreton wave did not overlap those of the EIT wave, but the continuation of the former is indicated by a filament oscillation. Data on the speed and location clearly show that the Moreton wave differed physically from the EIT wave in this case. The Moreton wave preceded the EIT wave, which is inconsistent with an identification of the EIT wave with a fast-mode MHD shock.