A Comparative Study between a Failed and a Successful Eruption Initiated from the Same Polarity Inversion Line in AR 11387

Abstract

In this paper, we analyzed a failed and a successful eruption that initiated from the same polarity inversion line within NOAA AR 11387 on 2011 December 25. They both started from a reconnection between sheared arcades, with distinct pre-eruption conditions and eruption details: before the failed one, the magnetic fields of the core region had a weaker non-potentiality; the external fields had a similar critical height for torus instability, and a similar local torus-stable region, but a larger magnetic flux ratio (of low corona and near-surface region) compared to the successful one. During the failed eruption, a smaller Lorentz force impulse was exerted on the outward ejecta; the ejecta had a much slower rising speed. Factors that might lead to the initiation of the failed eruption are identified: (1) a weaker non-potentiality of the core region, and a smaller Lorentz force impulse gave the ejecta a small momentum; (2) the large flux ratio, and the local torus-stable region in the corona provided strong confinements that made the erupting structure regain an equilibrium state.