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Solar Physics

, Volume 145, Issue 1, pp 205–206 | Cite as

Detection of a significant change in the solar diameter

  • Axel D. Wittmann
  • Edoardo Alge
  • Michele Bianda
Solar physics letters

Abstract

Drift-time measurements of the solar diameter made at Izaña and Locarno in 1990–1992 show a significant increase of the observed angular semidiameter when compared to results obtained at the same two sites in 1981. The observed increase of ≈0.4″ is not due to a systematic (or long-term) variation, but seems to reflect a more complicated behaviour with time: As both series of measurements were made around a maximum of the 11-year cycle, it seems that a variation in phase with solar activity (in the sense of the Secchi-Rosa law) can be ruled out.

Keywords

Solar Activity Complicated Behaviour Solar Diameter 
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.

References

  1. Delache, Ph., Gavryusev, V., Gavryuseva, E., Laclare. F., Régulo, C., Roca Cortés, T.: 1993, Astrophys. J. (in press, IAC Preprint 33/92)Google Scholar
  2. Wittmann, A.: 1973, Solar Phys.29, 333Google Scholar
  3. Wittmann, A., Bonet, J.A., Wöhl, H.: 1981, in: L. Cram, J.H. Thomas (ed.),The Physics of Sunspots, p. 424–433, National Solar ObservatoryGoogle Scholar
  4. Wittmann, A.D., Alge, E., Bianda, M.: 1991, Solar Phys.135, 243Google Scholar

Copyright information

© Kluwer Academic Publishers 1993

Authors and Affiliations

  • Axel D. Wittmann
    • 1
  • Edoardo Alge
    • 2
  • Michele Bianda
    • 2
  1. 1.Universitäts-SternwarteGöttingenGermany
  2. 2.Istituto Ricerche Solari LocarnoLocarno-MontiSwitzerland

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