Fractal Reconnection in Solar and Stellar Environments

TL;DR

This paper reviews recent observations and theories on fractal magnetic reconnection in solar and stellar environments, highlighting its role in energy release, particle acceleration, and the occurrence of superflares.

Contribution

It discusses the extension of the fractal reconnection model from solar to stellar flares, integrating recent observational data and theoretical developments.

Findings

Magnetic reconnection is widespread in the solar atmosphere.

Fractal current sheets are associated with plasmoid ejections and flares.

The fractal reconnection model applies to both solar and stellar superflares.

Abstract

Recent space based observations of the Sun revealed that magnetic reconnection is ubiquitous in the solar atmosphere, ranging from small scale reconnection (observed as nanoflares) to large scale one (observed as long duration flares or giant arcades). Often the magnetic reconnection events are associated with mass ejections or jets, which seem to be closely related to multiple plasmoid ejections from fractal current sheet. The bursty radio and hard X-ray emissions from flares also suggest the fractal reconnection and associated particle acceleration. We shall discuss recent observations and theories related to the plasmoid-induced-reconnection and the fractal reconnection in solar flares, and their implication to reconnection physics and particle acceleration. Recent findings of many superflares on solar type stars that has extended the applicability of the fractal reconnection model of solar flares to much a wider parameter space suitable for stellar flares are also discussed.