EDP Sciences
Free access
Volume 376, Number 1, September II 2001
Page(s) 224 - 231
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20010960

A&A 376, 224-231 (2001)
DOI: 10.1051/0004-6361:20010960

Cyclicities in the light variations of S Doradus stars

III. P Cygni
M. de Groot1, C. Sterken2 and A. M. van Genderen3

1  Armagh Observatory, College Hill, Armagh BT61 9DG, Northern Ireland
2  University of Brussels (VUB), Pleinlaan 2, 1050 Brussels, Belgium
3  Leiden Observatory, Postbus 9513, 2300 RA Leiden, The Netherlands

(Received 19 April 2001 / Accepted 2 July 2001 )

On the basis of new photometric observations and archived data published since 1907, we discuss the light variations of P Cygni. We conclude that there are $\alpha$ Cygni-type microvariations with a stable (pulsation) quasi-period of 17.3 days. There are also longer cycles of variation with $P\sim$ 100 d, so-called 100 d-type micro-variations, and with $P\sim 1500$-1600 d, a short S Dor-type phase.

Key words: stars: individual: P Cygni -- stars: variables -- stars: oscillations -- stars: supergiants

Offprint request: C. Sterken, csterken@vub.ac.be

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