Onset of the magnetic explosion in solar polar coronal X-ray jets

TL;DR

This study investigates the magnetic reconnection processes initiating polar coronal X-ray jets, revealing that internal and breakout reconnections occur in sequence, supporting the idea that these jets are scaled-down versions of larger solar eruptions like flares and CMEs.

Contribution

It provides detailed observational evidence on the timing and sequence of magnetic reconnections in X-ray jets, linking them to larger eruptive phenomena and emphasizing flux cancelation as a key trigger.

Findings

Runaway internal reconnection often starts after minifilament rise.

Breakout reconnection can initiate the eruption at a current sheet.

Eruption sequences support similarity to larger solar eruptions.

Abstract

We follow up on the Sterling et al (2015) discovery that nearly all polar coronal X-ray jets are made by an explosive eruption of closed magnetic field carrying a miniature filament in its core. In the same X-ray and EUV movies used by Sterling et al (2015), we examine the onset and growth of the driving magnetic explosion in 15 of the 20 jets that they studied. We find evidence that: (1) in a large majority of polar X-ray jets, the runaway internal/tether-cutting reconnection under the erupting minifilament flux rope starts after both the minifilaments rise and the spire-producing external/breakout reconnection have started and (2) in a large minority, (a) before the eruption starts there is a current sheet between the explosive closed field and the ambient open field, and (b) the eruption starts with breakout reconnection at that current sheet. The variety of event sequences in the eruptions supports the idea that the magnetic explosions that make polar X-ray jets work the same way as the much larger magnetic explosions that make a flare and coronal mass ejection (CME). That idea, and recent observations indicating that magnetic flux cancelation is the fundamental process that builds the field in and around the pre-jet mininfilament and triggers that fields jet-driving explosion, together suggest that flux cancelation inside the magnetic arcade that explodes in a flare/CME eruption is usually the fundamental process that builds the explosive field in the core of the arcade and triggers that fields explosion.