On the nature of reconnection at a solar coronal null point above a separatrix dome

TL;DR

This paper investigates magnetic reconnection at a solar coronal null point with a dome structure, revealing flux transfer mechanisms and field line dynamics through analytical and computational models.

Contribution

It provides new insights into spine-fan reconnection at coronal null points, highlighting flux transfer without separators and line flipping phenomena.

Findings

Significant magnetic flux transfer occurs during spine-fan reconnection.

Flux transfer happens across a current sheet around the null point.

Field line flipping resembles quasi-separatrix layer reconnection.

Abstract

Three-dimensional magnetic null points are ubiquitous in the solar corona, and in any generic mixed-polarity magnetic field. We consider magnetic reconnection at an isolated coronal null point, whose fan field lines form a dome structure. We demonstrate using analytical and computational models several features of spine-fan reconnection at such a null, including the fact that substantial magnetic flux transfer from one region of field line connectivity to another can occur. The flux transfer occurs across the current sheet that forms around the null point during spine-fan reconnection, and there is no separator present. Also, flipping of magnetic field lines takes place in a manner similar to that observed in quasi-separatrix layer or slip-running reconnection.