Onset of a Large Ejective Solar Eruption from a Typical Coronal-jet-base Field Configuration
Abstract
Utilizing multiwavelength observations and magnetic field data from the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA), SDO/Helioseismic and Magnetic Imager (HMI), the Geostationary Operational Environmental Satellite (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. 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 apart from that polarity inversion line; this evolution is consistent with the mechanism of tether-cutting reconnection for eruptions. Second, the eruption of the arcade that has the erupting flux rope in its core undergoes 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 minutes) the onset of the circular ribbon, 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 eruption (diameter of the circular ribbon ∼105 km) is analogous to that of coronal jets (base size ∼104 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.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 2017
- DOI:
- 10.3847/1538-4357/aa7c1b
- arXiv:
- arXiv:1706.09176
- Bibcode:
- 2017ApJ...845...26J
- Keywords:
-
- Sun: activity;
- Sun: flares;
- Sun: magnetic fields;
- Sun: X-rays;
- gamma rays;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 36 pages, 14 figures. Accepted for publication in ApJ