Time Variations of the Frequencies of Low-Degree Solar P-Modes

  • Martin F. Woodard
  • Robert W. Noyes
Conference paper
Part of the International Astronomical Union / Union Astronomique Internationale book series (IAUS, volume 123)


A comparison of three separate years (1980, 1984, 1985) of SMM/ACRIM solar total irradiance data reveals small but significant changes in the frequencies of low-degree solar p-modes. Specifically, a decrease in the mean frequency of the nine strongest ℓ = 0 and 1 oscillation peaks was observed between 1980 and 1984 such that \({\left\langle {\Delta v} \right\rangle _{1984 - 1980}} = - 0.41\pm 0.13\mu Hz.\)

A further comparison, between 1980 and 1985, gives \({\left\langle {\Delta v} \right\rangle _{1985 - 1980}} = - 0.45\pm 0.23\mu Hz.\)

Thus, the mean frequency of these modes is approximately 1.5 parts in 104 higher at the time of solar maximum than near solar minimum, a result which may shed light on the mechanism of the solar activity cycle.


Solar Minimum Solar Maximum Solar Radius Solar Activity Cycle Radius Variation 
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  1. 1.
    Woodard, M.F., and Noyes, R.W., Nature 318, 449–450 (1985).ADSCrossRefGoogle Scholar
  2. 2.
    Grec, G., Fossat, E. and Pomerantz, M., Sol. Phys. 82, 55–66 (1983).ADSCrossRefGoogle Scholar

Copyright information

© International Astronomical Union 1988

Authors and Affiliations

  • Martin F. Woodard
    • 1
  • Robert W. Noyes
    • 2
  1. 1.Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaUSA
  2. 2.Harvard-Smithsonian Center for AstrophysicsCambridgeUSA

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