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Astron. Astrophys. 328, 235-242

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Multiperiodicity in the atypical $\delta$ Sct star AN Lyn*

E. Rodríguez1, S.F. González-Bedolla2**, A. Rolland1, V. Costa1, M.J. López-González1, and P. López de Coca1

1Instituto de Astrofísica de Andalucía, CSIC, Apartado 3004, E-18080 Granada, Spain
2Instituto de Astronomía, UNAM, Apartado 70-264, CP-4510 México D.F., Mexico

Received 16 May 1997 / Accepted 4 July 1997


New uvby data collected of AN Lyn together with the reanalysis of old data establish that this star is a multiperiodic pulsator. Three independent frequencies ($\nu$1=10.1756, $\nu$2=18.1309 and $\nu$3=9.5598 cd-1) and some interactions between them are found to be present in the light curve. Changes in amplitude with a large time scale are confirmed for the main frequency. Moreover, changes in amplitude are also present for the secondary frequencies, especially for $\nu$3. After subtraction of the secondary frequencies from the light curves, the classical O-C method has been used to analyse the behaviour of the main period.

A comparison is made between AN Lyn and the other two known $\delta$ Sct stars with atypical light curves, i.e., V1719 Cyg and V798 Cyg. New uvby data have been also collected for V1719 Cyg and the O-C method has been used to analyse the behaviour of the main period. It is found that the main pulsation of this star can be well described by means of a linear ephemeris with a period of P=0.d26729700 over the last eighteen years. Finally, analysis of the different data sets available in the literature do not reveal significative changes in the amplitude of the main frequency of V1719 Cyg.

Key words: stars: variables: $\delta$ Scu - stars: individual: AN Lyn - stars: oscillations - techniques: photometric

*Table 5 will be accessible only in electronic form at the CDS

Send offprint requests to: E. Rodríguez (eloy@iaa.es)

© European Southern Observatory (ESO) 1997

Online publication: October 30, 1997
Last change: March 24, 1998