Are There Local Dynamos Acting in Sunspot Regions?

• Published in: The Astrophysical journal Vol. 975; no. 1; pp. 46 - 55
• Main Authors: Jin, Chunlan, Zhou, Guiping, Ji, Haisheng, Wang, Jingxiu
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 01.11.2024; IOP Publishing
• Subjects: Brightening; Evolution; Extreme ultraviolet radiation; Rotating generators; Solar activity; Solar dynamo; Solar magnetic fields; Solar physics; Sunspots; Ultraviolet radiation
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ad7820

In solar physics, a long-unanswered question is whether or not there are local dynamos acting in sunspot regions. Here we report an observed pattern of magnetic evolution that makes the sunspots alive with ample complexity and energy. This anomalous pattern manifests as peculiar bipolar magnetic emergences (BMEs), exhibiting the following characteristics: (1) the BMEs persistently appear beyond the penumbra, encircling the sunspot in an end-to-end configuration; (2) each BME gradually grows and separates its two polarities along an arc trajectory centered on the sunspot; (3) a circular brightening belt is manifested in the ultraviolet/extreme-ultraviolet radiations during the BMEs’ evolution; and (4) the sunspot regions with such an evolution pattern often exhibit vigorous solar activity, such as homogeneous major flares. The magnetic evolving pattern and relevant flare activity indicate the presence of a local dynamo, and we characterize it as a twisting-reconnecting dynamo.