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The Rotational Modulation of Ca II K in the Sun

Published online by Cambridge University Press:  12 April 2016

I. Sattarov  and
A. Hojaev
I. Sattarov
Affiliation:
Astronomical Institute of Uzbekistan Academy of Sciences, 700052 Tashkent, USSR
A. Hojaev
Affiliation:
Astronomical Institute of Uzbekistan Academy of Sciences, 700052 Tashkent, USSR

Extract

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The most widely used indicator of the stellar magnetic activity is the flux in the CaII K-line core (K-index) (Baliunas and Vaughan, 1985). The K-index data have also been used for measuring the rotation of stars. But using the method for the Sun gives different results (Keil and Worden, 1984; Singh and Livingston, 1987). The reason for the observed differences, besides those indicated by Singh and Livingston, may be the character of the distribution of active regions. This study is based on observations made at Tashkent Astronomical Observatory and the data published in SGD for solar cycle 21. We study the longitudional distribution of sunspots and plages. Some intervals of active longitudes (IAL) were selected and the evolution of them was studied. Active regions were found to concentrate in certain longitude intervals which are in nearly rigid rotation. Fig. 1 shows the longitudinal distribution of sunspots areas for 1983-84, as an example.

Type
Part III Solar magnetism and large-scale flows
Information
International Astronomical Union Colloquium , Volume 130: The Sun and Cool Stars: activity, magnetism, dynamos , 1991 , pp. 266 - 267
Copyright
Copyright © Springer-Verlag 1991

References

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