We demonstrate that major asymmetries in erupting filaments and CMEs, namely major twists and non-radial motions are typically related to the larger-scale ambient environment around eruptive events. Our analysis of prominence eruptions observed by the STEREO, SDO, and SOHO spacecraft shows that prominence spines retain, during the initial phases, the thin ribbon-like topology they had prior to the eruption. This topology allows bending, rolling, and twisting during the early phase of the eruption, but not before. The combined ascent and initial bending of the filament ribbon is non-radial in the same general direction as for the enveloping CME. However, the non-radial motion of the filament is greater than that of the CME. In considering the global magnetic environment around CMEs, as approximated by the Potential Field Source Surface (PFSS) model, we find that the non-radial propagation of both erupting filaments and associated CMEs is correlated with the presence of nearby coronal holes, which deflect the erupting plasma and embedded fields. In addition, CME and filament motions, respectively, are guided towards weaker field regions, namely null points existing at different heights in the overlying configuration. Due to the presence of the coronal hole, the large-scale forces acting on the CME may be asymmetric. We find that the CME propagates usually non-radially in the direction of least resistance, which is always away from the coronal hole. We demonstrate these results using both low- and high-latitude examples.
Coronal mass ejections, low coronal signatures Coronal mass ejections, initiation and propagation Magnetic fields, corona Coronal holes, prominences, formation and evolution Filaments
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We are indebted to the SOHO, STEREO/SECCHI and SDO teams. O.P. and S.M. are supported in this research by the NASA grant NNX09AG27G. The work of M.V. was conducted at the Jet Propulsion Laboratory, California Institute of Technology under a contract from the National Aeronautics and Space Administration. A.V. is supported by NASA contract S-136361-Y to the Naval Research Laboratory. SOHO is a mission of international cooperation between ESA and NASA. The SECCHI data are produced by an international consortium of the NRL, LMSAL, and NASA GSFC (USA), RAL and Univ. Birmingham (UK), MPS (Germany), CSL (Belgium), IOTA and IAS (France). The AIA data used here are courtesy of SDO (NASA) and the AIA consortium.