Dynamics of CMEs in the STEREO Field of View: Theory and Observation

The initial acceleration and the subsequent dynamics of coronal mass ejections (CMEs) are investigated using the new SECCHI data. Specifically, the erupting flux-rope model of CMEs is used to model observed CME trajectories beyond the 30 Rs LASCO field of view. The forces acting on CMEs in the inner corona and the heliosphere are explicitly calculated. In this work, we address two limitations imposed by the previous observations: (1) direct comparison of theory and data was limited to the LASCO field of view and (2) the 3D morphology and the direction of propagation were uncertain. The new SECCHI data allow one, for the first time, to extend model comparison/validation beyond the 30 Rs field of view, and the two-spacecraft view of the sun makes it possible to determine the 3D geometry of CMEs significantly better. We will theoretically model the dynamics of CMEs observed by STEREO A and B, from the low corona (EUVI) to the heliosphere (Heliospheric Imagers HI-1 and HI-2). Synthetic coronagraph images for the STEREO A and B observing positions will be used to constrain the 3D geometry of observed CMEs. In the lower corona, LASCO data will be compared with the SECCHI data. Work supported by ONR and NASA.