CURRENT HELICITY OF ACTIVE REGIONS AS A TRACER OF LARGE-SCALE SOLAR MAGNETIC HELICITY
- National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)
- School of Mathematics, University of Manchester, Manchester M13 9PL (United Kingdom)
- Department of Mechanical Engineering, Ben-Gurion University of Negev, POB 653, 84105 Beer-Sheva (Israel)
- IZMIRAN, Troitsk, Moscow Region 142190 (Russian Federation)
- Department of Physics, Moscow State University, Moscow 119992 (Russian Federation)
We demonstrate that the current helicity observed in solar active regions traces the magnetic helicity of the large-scale dynamo generated field. We use an advanced two-dimensional mean-field dynamo model with dynamo saturation based on the evolution of the magnetic helicity and algebraic quenching. For comparison, we also studied a more basic two-dimensional mean-field dynamo model with simple algebraic alpha-quenching only. Using these numerical models we obtained butterfly diagrams both for the small-scale current helicity and also for the large-scale magnetic helicity, and compared them with the butterfly diagram for the current helicity in active regions obtained from observations. This comparison shows that the current helicity of active regions, as estimated by -A {center_dot} B evaluated at the depth from which the active region arises, resembles the observational data much better than the small-scale current helicity calculated directly from the helicity evolution equation. Here B and A are, respectively, the dynamo generated mean magnetic field and its vector potential. A theoretical interpretation of these results is given.
- OSTI ID:
- 22037242
- Journal Information:
- Astrophysical Journal, Vol. 751, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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