High-Resolution Observation and Magnetic Modeling of a Solar Minifilament: the Formation, Eruption and Failing Mechanisms

TL;DR

This study combines high-resolution observations and magnetic modeling to explore the formation, eruption, and failure mechanisms of a solar minifilament, revealing a new external magnetic reconnection trigger and its link to coronal jets.

Contribution

It introduces a novel external magnetic reconnection mechanism triggered by flux cancellations as a trigger for minifilament eruptions, supported by detailed observations and magnetic field modeling.

Findings

Eruption is triggered by external magnetic reconnection.

Flux cancellation occurs between the minifilament's footpoint polarity and an external polarity.

A hyperbolic flux tube (HFT) is identified above the flux cancellation site.

Abstract

Minifilaments are widespread small-scale structures in the solar atmosphere. To better understand their formation and eruption mechanisms, we investigate the entire life of a sigmoidal minifilament located below a large quiescent filament observed by BBSO/GST on 2015 August 3. The H{\alpha} structure initially appears as a group of arched threads, then transforms into two J-shaped arcades, and finally forms a sigmoidal shape. SDO/AIA observations in 171{\AA} show that two coronal jets occur around the southern footpoint of the minifilament before the minifilament eruption. The minifilament eruption starts from the southern footpoint, then interacts with the overlying filament and fails. The aforementioned observational changes correspond to three episodes of flux cancellations observed by SDO/HMI. Unlike previous studies, the flux cancellation occurs between the polarity where southern footpoint of the minifilament is rooted in and an external polarity. We construct two magnetic field models before the eruption using the flux rope insertion method, and find an hyperbolic flux tube (HFT) above the flux cancellation site. The observation and modeling results suggest that the eruption is triggered by the external magnetic reconnection between the core field of the minifilament and the external fields due to flux cancellations. This study reveals a new triggering mechanism for minifilament eruptions and a new relationship between minifilament eruptions and coronal jets.