A bright coronal downflow seen in multi-wavelength observations: Evidence of a bifurcating flux-rope?

Abstract

Aims. We study the origin and characteristics of a bright coronal downflow seen after a coronal mass ejection associated with erupting prominences on 5 March 2000. Methods. This study extends that of Tripathi et al. (2006b, A&A, 449, 369) based on the Extreme-ultraviolet Imaging Telescope (EIT), the Soft X-ray Telescope (SXT) and the Large Angle Spectrometric Coronagraph (LASCO) observations. We combined those results with an analysis of the observations taken by the Ha and the Mk4 coronagraphs at the Mauna Loa Solar Observatory (MLSO). The combined data-set spans a broad range of temperature as well as continuous observations from the solar surface out to 30 R⊙. Results. The downflow started at around 1,6 R⊙ and contained both hot and cold gas. The downflow was observed in the Hα and the Mk4 coronagraphs as well as the EIT and the SXT and was approximately co-spatial and co-temporal providing evidence of multi-thermal plasma. The Ha and Mk4 images show cusp-shaped structures close to the location where the downflow started. Mk4 observations reveal that the speed of the downflow in the early phase was substantially higher than the free-fall speed, implying a strong downward acceleration near the height at which the downflow started. Conclusions. The origin of the downflow was likely to have been magnetic reconnection taking place inside the erupting flux rope that led to its bifurcation. © ESO 2007.