A Model for the Sources of the Slow Solar Wind

TL;DR

This paper presents a model explaining the slow solar wind's composition and wide angular extent by proposing narrow open-field corridors that form a web of separatrices in the heliosphere, supported by analytical and numerical evidence.

Contribution

The study introduces the S-web model, linking coronal magnetic structures to the broad angular distribution of the slow solar wind, supported by high-resolution MHD simulations and magnetic field observations.

Findings

The S-web model accounts for the slow wind's composition and angular width.

Numerical simulations show the formation of a web of separatrices matching observed properties.

The model suggests a connection between coronal magnetic topology and solar wind characteristics.

Abstract

Models for the origin of the slow solar wind must account for two seemingly contradictory observations: The slow wind has the composition of the closed field corona, implying that it originates from the continuous opening and closing of flux at the boundary between open and closed field. On the other hand, the slow wind also has large angular width, up to ~ 60{\circ}, suggesting that its source extends far from the open-closed boundary. We propose a model that can explain both observations. The key idea is that the source of the slow wind at the Sun is a network of narrow (possibly singular) open-field corridors that map to a web of separatrices and quasi-separatrix layers in the heliosphere. We compute analytically the topology of an open-field corridor and show that it produces a quasi-separatrix layer in the heliosphere that extends to angles far from the heliospheric current sheet. We then use an MHD code and MDI/SOHO observations of the photospheric magnetic field to calculate numerically, with high spatial resolution, the quasi-steady solar wind and magnetic field for a time period preceding the August 1, 2008 total solar eclipse. Our numerical results imply that, at least for this time period, a web of separatrices (which we term an S-web) forms with sufficient density and extent in the heliosphere to account for the observed properties of the slow wind. We discuss the implications of our S-web model for the structure and dynamics of the corona and heliosphere, and propose further tests of the model.