Observations and modeling of the early acceleration phase of erupting filaments involved in coronal mass ejections

TL;DR

This study analyzes the early acceleration of erupting filaments in coronal mass ejections using high-resolution observations and numerical simulations, revealing that their height evolution differs from existing models and emphasizing the need for more detailed modeling.

Contribution

It provides new observational data on filament acceleration profiles and demonstrates that current models do not fully explain these early phases, highlighting the importance of initial conditions.

Findings

Filament height follows a t^m profile with m near 3 during acceleration.

Observed rise profiles are incompatible with breakout, MHD-instability, and catastrophe models.

Numerical simulations of torus instability with initial velocity perturbations match observed profiles.

Abstract

We examine the early phases of two near-limb filament destabilization involved in coronal mass ejections on 16 June and 27 July 2005, using high-resolution, high-cadence observations made with the Transition Region and Coronal Explorer (TRACE), complemented by coronagraphic observations by Mauna Loa and the SOlar and Heliospheric Observatory (SOHO). The filaments' heights above the solar limb in their rapid-acceleration phases are best characterized by a height dependence h(t) ~ t^m with m near, or slightly above, 3 for both events. Such profiles are incompatible with published results for breakout, MHD-instability, and catastrophe models. We show numerical simulations of the torus instability that approximate this height evolution in case a substantial initial velocity perturbation is applied to the developing instability. We argue that the sensitivity of magnetic instabilities to initial and boundary conditions requires higher fidelity modeling of all proposed mechanisms if observations of rise profiles are to be used to differentiate between them. The observations show no significant delays between the motions of the filament and of overlying loops: the filaments seem to move as part of the overall coronal field until several minutes after the onset of the rapid-acceleration phase.