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


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.


Angular Velocity Sunspot Group Solar Rotation Recurrent Group Central Meridian 
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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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