2010 August 1-2 sympathetic eruptions: I. Magnetic topology of the source-surface background field

TL;DR

This study analyzes the magnetic topology of the solar corona during a series of synchronized eruptions in August 2010, revealing the role of pseudo-streamers and separators in triggering sympathetic eruptions and implications for solar wind models.

Contribution

It identifies the magnetic structures, including null points and separators, that likely facilitated the synchronized eruptions, supporting a simplified MHD model of sympathetic solar eruptions.

Findings

Pseudo-streamers are present at eruption sites.

Magnetic reconnection along separators likely triggered eruptions.

Results support the S-web model of the slow solar wind.

Abstract

A sequence of apparently coupled eruptions was observed on 2010 August 1-2 by SDO and STEREO. The eruptions were closely synchronized with one another, even though some of them occurred at widely separated locations. In an attempt to identify a plausible reason for such synchronization, we study the large-scale structure of the background magnetic configuration. The coronal field was computed from the photospheric magnetic field observed at the appropriate time period by using the potential field source-surface model. We investigate the resulting field structure by analyzing the so-called squashing factor calculated at the photospheric and source-surface boundaries, as well as at different coronal cross-sections. Using this information as a guide, we determine the underlying structural skeleton of the configuration, including separatrix and quasi-separatrix surfaces. Our analysis reveals, in particular, several pseudo-streamers in the regions where the eruptions occurred. Of special interest to us are the magnetic null points and separators associated with the pseudo-streamers. We propose that magnetic reconnection triggered along these separators by the first eruption likely played a key role in establishing the assumed link between the sequential eruptions. The present work substantiates our recent simplified magnetohydrodynamic model of sympathetic eruptions and provides a guide for further deeper study of these phenomena. Several important implications of our results for the S-web model of the slow solar wind are also addressed.