Astron. Astrophys. 333, L35-L38 (1998)

Letter to the Editor

The possible effects of an unusual resonance in very long period Cepheids

E. Antonello

Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807 Merate, Italy (e-mail: elio@merate.mi.astro.it)

Received 18 December 1997 / Accepted 26 February 1998

Abstract

The shape of the radial velocity and light curves of 24 long-period ( d) Cepheids in the Magellanic Clouds shows a progression with the period. The sequences of the radial velocity and light curves are based only on a small sample of stars; however, evident changes of the shape can be seen in Cepheids with period between 90 and 134 d. The Fourier parameter-period diagrams for the radial velocity curves show trends which remind in part those of Cepheids with period near 10 d. The plausible interpretation is a resonance, probably between the fundamental and the first overtone mode. The possible importance of this phenomenon for the study of stellar structure and evolution in relatively far galaxies is emphasized ¹.

Key words: stars: oscillations Cepheids Magellanic Clouds

SIMBAD Objects

Contents

• 1. Introduction
• 2. Data analysis
• 3. Discussion
• 4. Conclusion
• Acknowledgements
• References

© European Southern Observatory (ESO) 1998

Online publication: April 20, 1998
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