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Durham University

Department of Mathematical Sciences

Academic Staff

Publication details for Peter Wyper

Scott, Roger B., Pontin, David I. & Wyper, Peter F. (2019). Magnetic Structures at the Boundary of the Closed Corona: A Semi-automated Study of S-Web Morphology. The Astrophysical Journal 882(2): 125.

Author(s) from Durham

Abstract

Interchange reconnection is thought to play an important role in driving the dynamics of the slow solar wind. To
understand the details of this process, it is important to catalog the various magnetic structures that are present at
the boundary between open and closed magnetic flux. To this end we have developed a numerical method for
partitioning the coronal volume into individual flux domains using volume segmentation along layers of high
magnetic squashing degree (Q). Our publicly available implementation of this method is able to identify the
different magnetic structures within a coronal magnetic field model that define the open-closed boundary and
comprise the so-called Separatrix-Web (S-Web). With this we test previous predictions of how different
configurations of high-Q arcs within the S-Web are related to coronal magnetic field structures. Here we present
our findings from a survey of 11 different potential field source surface models, spanning from 2008 to 2017,
which offer a representative sample of the coronal magnetic field across nearly a complete solar cycle. Two key
findings of our analysis are that (i) “vertex” structures—where arcs of the S-Web meet away from the heliospheric
current sheet—are associated with underlying magnetic dome structures, and (ii) that any given arc of the S-Web is
almost equally as likely to be formed by a narrow corridor of open flux (corresponding to a hyperbolic flux tube) as
by the separatrix surface of a magnetic null. Together, these findings highlight the importance of a variety of
topological configurations for future studies of interchange reconnection and the acceleration of the solar wind.