Plasma Flows May Drive Solar Active Region Formation

The research analyzes the early evolutionary stages of active regions to address a fundamental question in heliophysics: whether magnetic structures or fluid motions are the dominant drivers of solar activity. The findings challenge the popular rising flux-tube model, which posits that twisted loops of strong magnetic field emerge from the Sun's interior to create these features. The investigation utilized optical images and full-vector magnetic field maps obtained by the Helioseismic and Magnetic Imager (HMI) aboard the Solar Dynamics Observatory.

By applying local correlation tracking to photospheric brightness elements, the authors constructed detailed maps of fluid-particle tracks. These maps allowed for a direct comparison between the observed magnetic configurations and the underlying plasma dynamics during the initial development of three distinct active regions. The popular rising-tube model suggests that an Omega-shaped loop of strong magnetic field rises through the subphotospheric layers.

If this model were correct, the emerging magnetic field would inevitably disrupt the surrounding supergranulation pattern. However, the data from this study indicate that the supergranulation pattern remains intact during the emergence of the active regions. This observation confirms a conclusion first made by Bumba and Howard in the mid-1960s, which stated that the supergranulation pattern is not destroyed by the emerging magnetic field of the developing active region.

The researchers found no signs of spreading flows on scales comparable to the size of the entire active region. The study notes that such disruption would be inevitable if a loop of the strong-magnetic-field flux tube rose through the subphotospheric layers. Instead, the authors conclude that plasma flows appear to be determinant with respect to magnetic fields.

Furthermore, the study revealed various forms of dissymmetry between the leading and trailing parts of the active regions. These asymmetries were observed during the analysis of the developing regions. The researchers also examined a well-developed sunspot group to investigate the timing of magnetic twist development.

They found that the twist of the magnetic configuration may develop much later than the group starts growing. The authors argue that the observed preservation of supergranulation and the delayed development of magnetic twist are incompatible with the idea of a rising flux tube. The preservation of supergranulation patterns and the delayed development of magnetic twist are key observations that challenge existing models.

Subject of Research: The role of plasma flows versus magnetic fields in the formation of solar active regions

Article Title: Solar Photospheric Flows and the Origin of Active Regions

Article References: Getling, A. V. (2026). Solar Photospheric Flows and the Origin of Active Regions. Solar Physics, 301(10), 162. https://doi.org/10.1007/s11207-026-02762-7

Image Credits: AI Generated

DOI: 10.1007/s11207-026-02762-7

Keywords: solar physics, active regions, plasma flows, magnetic fields, sunspots, supergranulation, Solar Dynamics Observatory, heliophysics, flux-tube model, photospheric dynamics, Solar, Photospheric