engleski

Interaction of a Moreton/EIT Wave and a Coronal Hole

We report high-cadence Halpha observations of a distinct Moreton wave observed at Kanzelhöhe Solar Observatory associated with the 3B/X3.8 flare and coronal mass ejection (CME) event of 2005 January 17. The Moreton wave can be identified in about 40 Halpha frames over a period of 7 minutes. The EIT wave is observed in only one frame, but the derived propagation distance is close to that of the simultaneously measured Moreton wave fronts, indicating that they are closely associated phenomena. The large angular extent of the Moreton wave allows us to study the wave kinematics in different propagation directions with respect to the location of a polar coronal hole (CH). In particular, we find that the wave segment whose propagation direction is perpendicular to the CH boundary (``frontal encounter'') is stopped by the CH, which is in accordance with observations reported from EIT waves. However, we also find that at a tongue-shaped edge of the coronal hole, where the front orientation is perpendicular to the CH boundary (the wave ``slides along'' the boundary), the wave signatures can be found up to 100 Mm inside the CH. These findings are briefly discussed in the frame of recent modeling results.

Shock Waves; Sun: Corona; Sun: Flares

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