Houston, TX 77005
12:00 p.m. Monday, Jan. 28, 2013
On Campus | Alumni
Determining the spatial structure of an interplanetary coronal mass ejection (ICME) and relating that structure back to the source CME is a very difficult problem. In-situ observations consist of individual tracks of plasma, magnetic field and composition measurements through the body of an ICME. Coronagraph measurements of the source CME provides some knowledge of the global structure, but little information about the plasma, magnetic field and composition of the the CME. Models of CME initiation, in particular MHD models, provide predictions of plasma and magnetic field quantities that can potentially be linked to in-situ observations. However, the evolution of the CME during transit and the single track observations available in-situ make this comparison difficult.We report on a new effort to understand the global structure of CMEs. Combining recent advances in multispacecraft data interpolation, reconstruction, and visualization with results from new methods of modeling ionic charge states in MHD simulations of CME initiation, we are able to interpret specific details of ICME plasma composition resulting from the magnetic topology and evolution of the CME. We focus on the ionic composition of two interplanetary coronal mass ejections observed in May 2007 by the ACE and STEREO spacecraft. These observations are analyzed in the context of the magnetic structure of the ejecta flux rope, sheath region, and surrounding solar wind flow. In both ICMEs, the enhanced iron charge state maps show a complex spatial structure: not only are there enhancements in the interior of each of the magnetic flux rope portions of the ICMEs, but there are clear enhancement signatures surrounding, and in some sense "linking," the two ejections. We determine the spatial structure of these events and relate that to source region conditions and we compare the results with charge state enhancements predicted by the flux cancellation and magnetic breakout MHD simulations.