We present a morphological study of the 2004 August 18 solar eruption that occurred in the active region NOAA 10656 near the west limb using extreme-ultraviolet (EUV) data from the Transition Region and Coronal Explorer (TRACE), Hα filtergram of Big Bear Solar Observatory, white light images of Mauna Loa Solar Observatory (MLSO), hard X-ray (HXR) data of the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), and microwave data of the Owens Valley Solar Array. In this event, we have an excellent set of observations for tracing the early evolution of the coronal mass ejection (CME) from a flux rope emergence to its propagation into space as a well-connected series of events thanks to the coronameter's field of view (FOV) down to 1.1 solar radius in an overlap with that of the TRACE. This data set reveals continuously evolving EUV, Hα, and WL features that suggest the rise of a small, low-lying loop, its writhing motion, break of the kinked loop at its crossing point, and transformation of the ejecta to the CME. The HXR and microwave sources are found in varying locations with a complicated temporal dependence, which, we interpret, is due to two successive flares in the event. The first flare appears to be associated with the rise of the small loop, which then triggers the second flare. During the second flare a HXR coronal source is detected at the crossing point of the kinked loop, and more intriguingly, the kinked loop apparently breaks at the crossing point of the two legs, which indicates a magnetic reconnection at the X-point configuration. After the break of the kinked UV loop, a CME structure shows up in the MLSO FOV, and propagates away from the Sun. It is concluded that this CME occurred due to the kink instability.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science
- Sun: coronal mass ejections (CMEs)
- Sun: flares
- Sun: X-rays, gamma rays