Observed evolutionary changes in the visual magnitude of the luminous blue variable P Cygni

  • Mart de Groot
  • Henny J. G. L. M. Lamers
III. Stellar Winds and Massive Stars
Part of the Lecture Notes in Physics book series (LNP, volume 401)


Historical observations of the star P Cygni (B1 Ia+) show that the star has steadily increased its visual brightness between 1700 and 1988 by 0.15 ± 0.02 magn/century. If we assume that the luminosity of the star remained constant (as predicted by evolutionary tracks of massive stars), the increase in brightness must be due to a steady decrease of the Bolometric Correction and hence of Teff at a rate of 6 ± 1 percent per century. This ist he first time ever that the evolution of a star has been observed in secular photometric variations.

Copyright information

© Springer-Verlag 1992

Authors and Affiliations

  • Mart de Groot
    • 1
  • Henny J. G. L. M. Lamers
    • 2
    • 3
  1. 1.Armagh ObservatoryCollege HillArmaghNorthern Ireland
  2. 2.SRON Laboratory for Space ResearchCA UtrechtThe Netherlands
  3. 3.Astronomical InstituteCC UtrechtThe Netherlands

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