Direct evidence: twisted flux tube emergence creates solar active regions

TL;DR

This study provides the first direct observational evidence that large twisted magnetic flux tubes emerge to form solar active regions, confirming a key theoretical model of solar activity.

Contribution

It offers direct observational proof supporting the emergence of large twisted flux tubes as the formation mechanism of solar active regions.

Findings

Magnetic winding is a key topological indicator of flux tube emergence.

Observations show signatures consistent with twisted flux tube emergence.

Supports the flux tube emergence model for active region formation.

Abstract

The magnetic nature of the formation of solar active regions lies at the heart of understanding solar activity and, in particular, solar eruptions. A widespread model, used in many theoretical studies, simulations and the interpretation of observations is that the basic structure of an active region is created by the emergence of a large tube of pre-twisted magnetic field. Despite plausible reasons and the availability of various proxies suggesting the veracity of this model, there has not yet been any direct observational evidence of the emergence of large twisted magnetic flux tubes. Thus, the fundamental question, "are active regions formed by large twisted flux tubes?" has remained open. In this work, we answer this question in the affirmative and provide direct evidence to support this. We do this by investigating a robust topological quantity, called magnetic winding, in solar observations. This quantity, combined with other signatures that are currently available, provides the first direct evidence that large twisted flux tubes do emerge to create active regions.