Podladchikova, T ; Veronig, A ; Dissauer, K ; Temmer, M ; Podladchikova, O

published in The Astrophysical Journal, Volume 877 issue Issue 2, pp. article id. 68, 14 pp.

Abstract: EUV waves are large-scale disturbances in the solar corona initiated by coronal mass ejections. However, solar EUV images show only the projection of the wave fronts along the line-of-sight of the spacecraft. We perform 3D reconstructions of EUV wave front heights using multi-point observations from STEREO-A and STEREO-B, and study their evolution to properly estimate the EUV wave kinematics. A new method is presented to solve the matching problem of the EUV wave crest on pairs of STEREO-A/-B images by combining epipolar geometry with the investigation of perturbation profiles. The proposed approach is applicable at the early and maximum stage of the event when STEREO-A and STEREO-B see different facets of the EUV wave, but also at the later stage when the wave front becomes diffusive and faint. The method is applied to two events observed at different separation of the STEREO spacecraft (42◦ and 91◦). For the 7 December 2007 event, we find an EUV wave front height of 90–104 Mm, decreasing later to 7–35 Mm. Including the varying height of the EUV wave front allows us to correct the wave kinematics for the effects of projection, resulting in velocities in the range 217–266 km/s. For the 13 February 2009 event, the wave front height doubled from 54 to 93 Mm over 10 min, and the velocity derived is 205–208 km/s. In the two events under study, the corrected speeds differ by up to 25% from the uncorrected ones, depending on the evolution of the wave front height.

Keyword(s): Sun: activity — Sun: corona — Sun: UV radiation — waves
DOI: 10.3847/1538-4357/ab1b3a
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