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 Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We discuss a numerical 3D radiation-MHD simulation of penumbral finestructure in a small sunspot. This simulation shows the development of shortfilamentary structures with horizontal flows, similar to observed Evershedflows, and an inward propagation of these structures at a speed compatible withobservations. We conclude that the Evershed flow represents the horizontal flowcomponent of overturning convection in gaps with strongly reduced fieldstrength. The top of the flow is always directed outward--away from the umbra--because of the broken symmetry due to the inclined magnetic field. Upflowsoccur in the inner parts of the gaps and most of the gas turns over radially(outwards and sideways), and descends back down again. The ascending, coolingand overturning flow tends to bend magnetic field lines down, forcing aweakening of the field that makes it easier for gas located in an adjacentlayer--further in--to initiate a similar sequence of motion, aided by lateralheating, thus causing the inward propagation of the filament.

Convection and the origin of Evershed flows in sunspot penumbrae