Quadrature STEREO Observations Determine the Nature of EUV Waves
Abstract
One of the major discoveries of EIT on SOHO was the observation of large-scale EUV intensity disturbances which travel over significant fractions of the solar disk. These `EUV waves' are associated with CME onsets and can be either an MHD wave triggered by the eruption or the footprints of the associated CME, which currently is a subject of intense debate. EUV waves are better observed when their source region is close to disk center, whereas CME onsets and CMEs in general are better observed off-limb. Therefore, simultaneous multi-viewpoint observations of EUV waves are best suited to clarify the nature of these transients and to determine their true relationship with CMEs.
We present here the first quadrature STEREO observations of an EUV wave. The wave was observed on 2009 February 13 by both satellites, which were at a separation of 90 degrees. The wave originated from an erupting active region near disk center as seen from SC B and propagated over almost the entire visible solar disk. For SC A the active region was at the east limb and showed a small erupting bubble, expanding impulsively in both radial and lateral directions and inducing deflections of nearby and remote coronal structures. We present high cadence EUVI and COR1 measurements of both the wave (SC B), and the expanding EUV bubble (SC A), and of the resulting white-light CME (SC A; COR1). These would allow to quantify for the first time the true sizes and expansion characteristics of both the EUV wave and the associated CME. Finally, we search for wave-associated features in 3D MHD simulations of CME onsets based on ideal MHD instabilities. These are compared with the STEREO observations.- Publication:
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AAS/Solar Physics Division Meeting #40
- Pub Date:
- May 2009
- Bibcode:
- 2009SPD....40.2603K