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Astron. Astrophys. 342, 167-172 (1999)

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6. Conclusions

There is quite strong evidence for a linearly increasing period in the dataset of maximum times, the evidence for a period change in the dataset of minima is weak. There is substantial cycle-to-cycle variation in the pulsations (standard error [FORMULA] d). There is no compelling evidence that the apparent cyclical period changes are real; the residuals left after fitting a linear period increase plus intrinsic period scatter to the maxima (or intrinsic period scatter only, to the minima) have properties consistent with being white noise. The Lombard frequency domain test for a changing period applied to the residuals, also gives unconvincing significance levels. The low gradient of the luminosity change with period is compatible with the star undergoing a rise in luminosity when H shell-burning takes over.

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© European Southern Observatory (ESO) 1999

Online publication: December 22, 1998