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Long-term stellar activity: three decades of observations

Published online by Cambridge University Press:  25 May 2016

R.A. Donahue
R.A. Donahue*
Affiliation:
Harvard-Smithsonian Center for Astrophysics 60 Garden St., Cambridge, MA 02138-1596 USA

Extract

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Knowledge of the solar sunspot cycle extends back to the mid-19th century with the work of Schwabe (1843) and Wolf (1856). The mean cycle period of the Sun is 11 years, however, individual cycle lengths range from 7 to 13 years (Eddy 1977). In this century, however, the length of the solar cycle has been closer to 10 years (Donahue and Baliunas 1992a). A complete explanation of the solar magnetic activity and its variations has not yet been produced, although a hydromagnetic dynamo is frequently posited as the source of solar (and therefore stellar) magnetic activity. Empirical measurements of those stars in the H-R Diagram which have convective zones and surface magnetic activity provide the boundary conditions and the range of behavior which must be explained by any all-encompassing theory explaining stellar magnetic activity, and activity cycles.

Type
Session III: “Photospheric Phenomena: Results”
Information
Symposium - International Astronomical Union , Volume 176: Stellar Surface Structure , 1996 , pp. 261 - 268
Copyright
Copyright © Kluwer 1996 

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