# Onset of a Large Ejective Solar Eruption from a Typical Coronal-Jet-Base Field Configuration

## TL;DR

This study analyzes a large solar eruption involving a complex three-ribbon flare, revealing that different magnetic reconnection mechanisms trigger the event, which shares features with smaller-scale jets, demonstrating the universality of eruption processes across size scales.

## Contribution

It provides detailed observational evidence of a large-scale eruption involving both tether-cutting and breakout reconnection mechanisms within a fan-spine magnetic topology.

## Key findings

- Eruption initiated by tether-cutting reconnection 12 minutes before circular ribbon appearance.
- The event's magnetic setup is similar to smaller coronal jets, indicating scale-invariant eruption processes.
- Large-scale eruption features a 100,000 km diameter circular ribbon and a 10,000 km base size.

## Abstract

Utilizing multiwavelength observations and magnetic field data from SDO/AIA, SDO/HMI, GOES and RHESSI, we investigate a large-scale ejective solar eruption of 2014 December 18 from active region NOAA 12241. This event produced a distinctive three-ribbon flare, having two parallel ribbons corresponding to the ribbons of a standard two-ribbon flare, and a larger-scale third quasi-circular ribbon offset from the other two ribbons. There are two components to this eruptive event. First, a flux rope forms above a strong-field polarity-inversion line and erupts and grows as the parallel ribbons turn on, grow, and spread part from that polarity-inversion line; this evolution is consistent with the tether-cutting-reconnection mechanism for eruptions. Second, the eruption of the arcade that has the erupting flux rope in its core under goes magnetic reconnection at the null point of a fan dome that envelops the erupting arcade, resulting in formation of the quasi-circular ribbon; this is consistent with the breakout reconnection mechanism for eruptions. We find that the parallel ribbons begin well before (12 min) circular ribbon onset, indicating that tether-cutting reconnection (or a non-ideal MHD instability) initiated this event, rather than breakout reconnection. The overall setup for this large-scale (circular-ribbon diameter 100000 km) eruption is analogous to that of coronal jets (base size 10000 km), many of which, according to recent findings, result from eruptions of small-scale minifilaments. Thus these findings confirm that eruptions of sheared-core magnetic arcades seated in fan-spine null-point magnetic topology happen on a wide range of size scales on the Sun.