Does Nearby Open Flux Affect the Eruptivity of Solar Active Regions?

TL;DR

This study investigates whether proximity to open magnetic flux influences the eruptivity of solar active regions, finding that access to open fields correlates with higher eruption rates in X-class flares.

Contribution

It provides empirical evidence linking open magnetic flux access to increased likelihood of solar flare eruptions, using a sample of 56 flares and potential field modeling.

Findings

Access to open fields increases eruptive flare likelihood.

Eruptive X-class flares are more often near open magnetic flux.

Small sample size limits statistical significance.

Abstract

The most energetic solar flares are typically associated with the ejection of a cloud of coronal material into the heliosphere in the form of a coronal mass ejection (CME). However, there exist large flares which are not accompanied by a CME. The existence of these non-eruptive flares raises the question of whether such flares suffer from a lack of access to nearby open fields in the vicinity above the flare (reconnection) site. In this study, we use a sample of 56 flares from Sunspot Cycles 23 and 24 to test whether active regions that produce eruptive X-class flares are preferentially located near coronal magnetic field domains that are open to the heliosphere, as inferred from a potential field source surface model. The study shows that X-class flares having access to open fields are eruptive at a higher rate than those for which access is lacking. The significance of this result should be moderated due to the small number of non-eruptive X-class flares in the sample, based on the associated Bayes factor.