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Astron. Astrophys. 324, 133-136 (1997)

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The galactic double-mode Cepheids

II. Properties of the generalized phase differences

E. Poretti 1 and I. Pardo 2

1 Osservatorio Astronomico di Brera, Via Bianchi 46, I-22055 Merate, Italy (poretti@merate.mi.astro.it)
2 Università di Milano, I-20100 Milano, Italy

Received 28 November 1996 / Accepted 3 February 1997


By considering the least-squares fits of the double-mode Cepheid light curves discussed in Paper I we defined their properties by their Fourier parameters and generalized phase differences [FORMULA]. When plotting the latter quantities as a function of the order, the second order terms are confined in the region just below 3 [FORMULA] /2; the third order terms have [FORMULA], the fourth order ones cluster around 2 [FORMULA] (or 0), the fifth order ones seem to have [FORMULA] /2. The mean [FORMULA] values are also regularly spaced. The progression of the [FORMULA] values as function of period was investigated and the signature of a possible resonance near 6.0 d was found.

Key words: methods: data analysis – stars: oscillations – Cepheids – Galaxy: stellar content

Send offprint requests to: E. Poretti

© European Southern Observatory (ESO) 1997

Online publication: May 26, 1998