Observations and Modeling of the Early Acceleration Phase of Erupting Filaments Involved in Coronal Mass Ejections

Abstract

We examine the early phases of two near-limb filament destabilizationsinvolved in coronal mass ejections (CMEs) on 2005 June 16 and July 27,using high-resolution, high-cadence observations made with theTransition Region and Coronal Explorer (TRACE), complemented bycoronagraphic observations by the Mauna Loa Solar Observatory (MLSO) andthe Solar and Heliospheric Observatory (SOHO). The filaments' heightsabove the solar limb in their rapid-acceleration phases are bestcharacterized by a height dependence h(t)~tm with m near, orslightly above, 3 for both events. Such profiles are incompatible withpublished results for breakout, MHD-instability, and catastrophe models.We show numerical simulations of the torus instability that approximatethis height evolution in case a substantial initial velocityperturbation is applied to the developing instability. We argue that thesensitivity of magnetic instabilities to initial and boundary conditionsrequires higher fidelity modeling of all proposed mechanisms ifobservations of rise profiles are to be used to differentiate betweenthem. The observations show no significant delays between the motions ofthe filament and of overlying loops: the filaments seem to move as partof the overall coronal field until several minutes after the onset ofthe rapid-acceleration phase.