Subsurface Flows in and Around Active Regions with Rotating and Non-rotating Sunspots

TL;DR

This study investigates subsurface horizontal flows beneath different active regions with rotating and non-rotating sunspots, revealing significant variations influenced by flux emergence, decay, and sunspot rotation.

Contribution

It provides detailed analysis of subsurface flow variations in active regions with rotating and non-rotating sunspots using ring diagram techniques.

Findings

Higher horizontal velocities in emerging-flux regions compared to decaying regions.

Significant temporal variation in flow profiles, especially in rotating sunspot regions.

Localized plasma motion effects near rotating sunspots.

Abstract

The temporal variation of the horizontal velocity in subsurface layers beneath three different types of active regions is studied using the technique of ring diagrams. In this study, we select active regions (ARs) 10923, 10930, 10935 from three consecutive Carrington rotations: AR 10930 contains a fast-rotating sunspot in a strong emerging active region while other two have non-rotating sunspots with emerging flux in AR 10923 and decaying flux in AR 10935. The depth range covered is from the surface to about 12 Mm. In order to minimize the influence of systematic effects, the selection of active and quiet regions is made so that these were observed at the same heliographic locations on the solar disk. We find a significant variation in both components of the horizontal velocity in active regions as compared to quiet regions. The magnitude is higher in emerging-flux regions than in the decaying-flux region, in agreement with earlier findings. Further, we clearly see a significant temporal variation in depth profiles of both zonal and meridional flow components in AR 10930, with the variation in the zonal component being more pronounced. We also notice a significant influence of the plasma motion in areas closest to the rotating sunspot in AR 10930 while areas surrounding the non-rotating sunspots in all three cases are least affected by the presence of the active region in their neighborhood.