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

Light bridges, the bright structure dividing umbrae in sunspot regions, showvarious activity events. In Paper I, we reported on analysis ofmulti-wavelength observations of a light bridge in a developing active region(AR) and concluded that the activity events are caused by magnetic reconnectiondriven by magnetconvective evolution. The aim of this second paper is toinvestigate the detailed magnetic and velocity structures and the formationmechanism of light bridges. For this purpose, we analyze numerical simulationdata from a radiative magnetohydrodynamics model of an emerging AR. We findthat a weakly-magnetized plasma upflow in the near-surface layers of theconvection zone is entrained between the emerging magnetic bundles that appearas pores at the solar surface. This convective upflow continuously transportshorizontal fields to the surface layer and creates a light bridge structure.Due to the magnetic shear between the horizontal fields of the bridge and thevertical fields of the ambient pores, an elongated cusp-shaped current layer isformed above the bridge, which may be favorable for magnetic reconnection. Thestriking correspondence between the observational results of Paper I and thenumerical results of this paper provides a consistent physical picture of lightbridges. The dynamic activity phenomena occur as a natural result of the bridgeformation and its convective nature, which has much in common with those ofumbral dots and penumbral filaments.

Light Bridge in a Developing Active Region. II. Numerical Simulation of Flux Emergence and Light Bridge Formation