The 26 April 2008 CME; a Case Study Tracking a CME into the Heliosphere

With the current unique constellation of spacecraft, we are studying the origins of CMEs, their 3D structure and how they propagate through the heliosphere. Here we present the results of a case study of one well observed event that occurred during the Whole Heliosphere Interval (WHI), originating at the Sun on 26 April 2008. The event arose from a cluster of 3 active regions that evolved over several solar rotations centered on WHI. The CME was moderately fast with evidence of a shock and was associated with a coronal arcade, coronal dimming and an EUV wave. The April 26 CME originated from disk center for STEREO-B and apparently caused a small SEP event and shock and possible magnetic cloud at STEREO-B on April 29. A brief IP type II suggests that this event had the lowest starting frequency ever observed, which has implications for the medium through which the shock propagates. Possible ejecta was detected in situ at STEREO-B. The Fe charge states suggest that there was a CIR-type interface with some bidirectional electron streaming present. This is confirmed by SMEI 3D reconstructions of density indicating that the ICME interacted with a preexisting CIR. The ICME was also imaged by the SECCHI HI imagers; both the SMEI and HI data permit us to track the dense material from the Sun past 1 AU.