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Variation of Even and Odd Parity in the Solar Dynamo

Published online by Cambridge University Press:  08 February 2017

A. Brandenburg ,
R. Meinel ,
D. Moss  and
I. Tuominen
A. Brandenburg
Affiliation:
1Observatory and Astrophysics Laboratory, University of Helsinki Tähtitorninmäki, SF-00130 Helsinki, Finland
R. Meinel
Affiliation:
2Sternwarte Babelsberg, Rosa-Luxemburg-Str. 17a, 1591 Potsdam, German Democratic Republic
D. Moss
Affiliation:
3Dept. of Mathematics, The University, Manchester M13 9PL, England
I. Tuominen
Affiliation:
1Observatory and Astrophysics Laboratory, University of Helsinki Tähtitorninmäki, SF-00130 Helsinki, Finland

Abstract

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We have studied axisymmetric nonlinear αω-dynamo models taking the interaction between even and odd parities fully into account. It turns out that the dominating type of symmetry is not always determined uniquely, but it can vary on a very long time scale compared to the period of the magnetic cycle. In some cases the frequency of this long term variation is close to the beat frequency of the two solutions with purely dipolar and purely quadrupolar parity. The occurrence of a second frequency is typical of solutions whose trajectory describes a torus in the phase space. We argue that this finding is of relevance for understanding secular variations observed in the Sun. For example measurements of sunspots indicate that the spot number on the northern hemisphere at present exceeds the number on the southern hemisphere. The reverse seems to have been the case at the end of last century.

Type
VI. Generation of Solar Magnetic Fields
Information
Symposium - International Astronomical Union , Volume 138: Solar Photosphere: Structure, Convection and Magnetic Fields , 1990 , pp. 379 - 382
Copyright
Copyright © Kluwer 1990 

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