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Solar Physics

, Volume 74, Issue 1, pp 153–163 | Cite as

Positions of sunspot groups and solar rotation

  • Jaakko Tuominen
  • Juhani Kyrölsainen
The Sun:Structure Oscillations, Magnetic Cycle, Surface Variations

Abstract

The question is studied whether the one-year solar oscillation found by V. F. Chistyakov for the years 1965–1973 can be traced in the observations of sunspots of 1874–1971 published by Greenwich Observatory. The result is negative. But the study leads to the following two conclusions: (1) The average observable centres of gravity of spot groups are variably displaced towards the central meridian or towards the limb, the time scale of this variability being of the order of 70 years. Thus the angular velocity should be determined from recurrent groups in transit of the central meridian only. (2) The angular velocity will be smaller when determined from older spots.

Keywords

Angular Velocity Sunspot Group Solar Rotation Recurrent Group Central Meridian 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. Anttila, R. and Tuominen, J.: 1977, Bull. Astron. Inst. Czech. 28, 253.Google Scholar
  2. Chistyakov, V. G.: 1976, Bull. Astron. Inst. Czech. 27, 84.Google Scholar
  3. Godoli, G. and Mazzucconi, F.: 1979, Solar Phys. 64, 247.Google Scholar
  4. Greenwich Observatory: 1874–1971. The material is obtained from the following publications: Photoheliographic Results 1874–1885, Edinburgh 1907; Catalogue of Recurrent Groups for the Years 1874 to 1906, in Appendix to Greenwich Observations 1907; Greenwich Observations 1886 to 1905 and 1907 to 1938; Greenwich Photoheliographic Results 1939 to 1955; Royal Observatory Bulletin 1956 to 1961; Royal Observatory Annals 1962 to 1971.Google Scholar
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  8. Tuominen, J. and I. V. Tuominen: 1978, Proceedings of the Workshop on Solar Rotation, Catania, p. 228.Google Scholar

Copyright information

© D. Reidel Publishing Co 1981

Authors and Affiliations

  • Jaakko Tuominen
    • 1
  • Juhani Kyrölsainen
    • 1
  1. 1.Observatory and Astrophysics Laboratory, University of HelsinkiTähtitorninmäkiHelsinki 13Finland

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