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Current helicity constraints in solar dynamo models

Published online by Cambridge University Press:  18 July 2013

D. Sokoloff ,
H. Zhang ,
D. Moss ,
N. Kleeorin ,
K. Kuzanyan ,
I. Rogachevski ,
Yu Gao  and
H. Xu
D. Sokoloff
Affiliation:
Department of Physics, Moscow State University, Moscow 119992, Russia email: sokoloff.dd@gmail.com
H. Zhang
Affiliation:
National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China email: hzhang@bao.ac.cn
D. Moss
Affiliation:
School of Mathematics, University of Manchester, Manchester M13 9PL, UK email: moss@maths.man.ac.uk
N. Kleeorin
Affiliation:
Department of Mechanical Engineering, Ben-Gurion University of Negev, POB 653, 84105 Beer-Sheva, Israel email: nat@menix.bgu.ac.il
K. Kuzanyan
Affiliation:
IZMIRAN, Troitsk, Moscow Region 142190, Russia email: kuzanyan@izmiran.ru
I. Rogachevski
Affiliation:
Department of Mechanical Engineering, Ben-Gurion University of Negev, POB 653, 84105 Beer-Sheva, Israel email: gary@bgu.ac.il
Yu Gao
Affiliation:
National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China email: hzhang@bao.ac.cn
H. Xu
Affiliation:
National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China email: hzhang@bao.ac.cn
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Abstract

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We investigate to what extent the current helicity distribution observed in solar active regions is compatible with solar dynamo models. We use an advanced 2D mean-field dynamo model with dynamo action largely concentrated near the bottom of the convective zone, and dynamo saturation based on the evolution of the magnetic helicity and algebraic quenching. For comparison, we also studied a more basic 2D mean-field dynamo model with simple algebraic alpha quenching only. Using these numerical models we obtain butterfly diagrams for both the small-scale current helicity and the large-scale magnetic helicity, and compare 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·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.

Keywords

Sun: magnetic fields – dynamo – interior – surface activity – sunspots
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 8 , Symposium S294: Solar and Astrophysical Dynamos and Magnetic Activity , August 2012 , pp. 313 - 318
Copyright
Copyright © International Astronomical Union 2013 

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