paper

Estimation of the lifetime of slow-decaying unipolar active regions in the framework of the turbulent erosion model

arXiv:2403.04422 · doi:10.1007/s11207-024-02278-y

Abstract

We explore properties and behavior of slow-decaying unipolar sunspot groups in the framework of the turbulent erosion model suggested by Petrovay and Moreno-Insertis (1997). The basic concept of the model is the suppression of a turbulent diffusivity inside a magnetic flux tube by strong magnetic fields. As a result, the outer turbulent plasma detaches magnetic features primarily from the external border of a magnetic flux tube. The radius of the tube exhibits inward progression at a constant rate. The model predicts older sunspots to decay slower and it seems to be very promising to explain the slow decay of long-living unipolar sunspot groups. By analyzing the magnetic structure associated with a sunspot, we did reveal a gradual decrease of the magnetic structure radius at a constant rate implying the validity of the model. However, in some cases the derived velocity of the radius decrease was too low: our calculations provided implausibly high estimations for the lifetime and maximal area of such sunspots. We discuss possible additional mechanisms affecting the decay rate of such peculiar sunspots.

arXiv comment11 pages, 2 figures

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