English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The nature of three-dimensional reconnection when a twisted flux tube eruptsduring an eruptive flare or coronal mass ejection is considered. Thereconnection has two phases: first of all, 3D "zipper reconnection" propagatesalong the initial coronal arcade, parallel to the polarity inversion line(PIL), then subsequent quasi-2D "main phase reconnection" in the low coronaaround a flux rope during its eruption produces coronal loops and chromosphericribbons that propagate away from the PIL in a direction normal to it.  One scenario starts with a sheared arcade: the zipper reconnection creates atwisted flux rope of roughly one turn ($2\pi$ radians of twist), and then mainphase reconnection builds up the bulk of the erupting flux rope with arelatively uniform twist of a few turns. A second scenario starts with apre-existing flux rope under the arcade. Here the zipper phase can create acore with many turns that depend on the ratio of the magnetic fluxes in thenewly formed flare ribbons and the new flux rope. Main phase reconnection thenadds a layer of roughly uniform twist to the twisted central core. Both phasesand scenarios are modeled in a simple way that assumes the initial magneticflux is fragmented along the PIL. The model uses conservation of magnetichelicity and flux, together with equipartition of magnetic helicity, to deducethe twist of the erupting flux rope in terms the geometry of the initialconfiguration.  Interplanetary observations show some flux ropes have a fairly uniform twist,which could be produced when the zipper phase and any pre-existing flux ropepossess small or moderate twist (up to one or two turns). Other interplanetaryflux ropes have highly twisted cores (up to five turns), which could beproduced when there is a pre-existing flux rope and an active zipper phase thatcreates substantial extra twist.

Flux-Rope Twist in Eruptive Flares and CMEs: due to Zipper and Main-Phase Reconnection