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Solar Physics

, Volume 188, Issue 2, pp 225–236 | Cite as

Measurement of Kodaikanal White-Light Images – III. Rotation Rates and Activity Cycle Variations

  • S.S. Gupta
  • K.R. Sivaraman
  • Robert F. Howard
Article

Abstract

The Kodaikanal sunspot data set covering the interval 1906–1987 is analyzed for differential rotation of sunspots of different sizes. As is known, smaller sunspots rotate faster than larger sunspots, and this result is verified in the analysis of this data set. These results agree well with the Mount Wilson sunspot results published earlier. The activity cycle dependence of sunspot rotation is studied. An increase in this rate at the minimum phase is seen, which has been reported earlier. It is demonstrated that this cycle variation is seen for sunspots in all size categories, which suggests that it is not a relative increase in the number of the faster-rotating small sunspots that causes the cycle dependence. These results are discussed as they may relate to subsurface dynamic properties of the Sun.

Keywords

Dynamic Property Relative Increase Rotation Rate Activity Cycle Size Category 
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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Copyright information

© Kluwer Academic Publishers 1999

Authors and Affiliations

  • S.S. Gupta
    • 1
  • K.R. Sivaraman
    • 1
  • Robert F. Howard
    • 2
  1. 1.Indian Institute of AstrophysicsBangaloreIndia
  2. 2.National Solar Observatory, National Optical Astronomy ObservatoriesTucsonU.S.A

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