170 research outputs found
Interaction of a Moreton/EIT wave and a coronal hole
We report high-cadence H-alpha observations of a distinct Moreton wave
observed at Kanzelhoehe Solar Observatory associated with the 3B/X3.8 flare and
CME event of 2005 January 17. The Moreton wave can be identified in about 40
H-alpha frames over a period of 7 min. 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 (Thompson et al. 1998). 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.Comment: 14 pages, 6 figures, accepted for publication in the Ap
- …