Shock-related radio emission during coronal mass ejection lift-off?
| dc.creator | Pohjolainen, S. | |
| dc.date | 2008-03-13 | |
| dc.date.accessioned | 2026-07-07T09:58:03Z | |
| dc.date.available | 2026-07-07T09:58:03Z | |
| dc.description | Aims: We identify the source of fast-drifting decimetric-metric radio emission that is sometimes observed prior to the so-called flare continuum emission. Fast-drift structures and continuum bursts are also observed in association with coronal mass ejections (CMEs), not only flares. Methods: We analyse radio spectral features and images acquired at radio, H-alpha, EUV, and soft X-ray wavelengths, during an event close to the solar limb on 2 June 2003. Results: The fast-drifting decimetric-metric radio burst corresponds to a moving, wide emission front in the radio images, which is normally interpreted as a signature of a propagating shock wave. A decimetric-metric type II burst where only the second harmonic lane is visible could explain the observations. After long-lasting activity in the active region, the hot and dense loops could be absorbing or suppressing emission at the fundamental plasma frequency. The observed burst speed suggests a super-Alfvenic velocity for the burst driver. The expanding and opening loops, associated with the flare and the early phase of CME lift-off, could be driving the shock. Alternatively, an instantaneous but fast loop expansion could initiate a freely propagating shock wave. The later, complex-looking decametre-hectometre wave type III bursts indicate the existence of a propagating shock, although no interplanetary type II burst was observed during the event. The data does not support CME bow shock or a shock at the flanks of the CME as the origin of the fast-drift decimetric-metric radio source. Therefore super-Alfvenic loop expansion is the best candidate for the initiation of the shock wave, and this result challenges the current view of metric/coronal shocks originating either in the flanks of CMEs or from flare blast waves. | |
| dc.description | 4 pages, 3 figures, accepted by A&A (Research Note) | |
| dc.identifier | https://arxiv.org/abs/0803.2014 | |
| dc.identifier | http://arxiv.org/abs/0803.2014 | |
| dc.identifier | Astron. Astrophys. 483 (2008) 297-300 | |
| dc.identifier | doi:10.1051/0004-6361:20079155 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/167573 | |
| dc.subject | Astrophysics | |
| dc.title | Shock-related radio emission during coronal mass ejection lift-off? | |
| dc.type | text |