Is the small-amplitude cepheid SZ Tau a possible overtone pulsator?
Andrievsky, S. M.; Kovtyukh, V. V.; Klochkova, V. G.; Usenko, I. A.; Panchuk, V. E.; Gorlova, N. I.
Abstract
On the base of 8 high-resolution CCD spectra, obtained by the 6-m telescope of SAO RAS (Russia) and 4-m telescope of KPNO (USA), we have determined the mean values of atmospheric parameters for small-amplitude Cepheid SZ Tau. Since SZ Tau is a member of NGC 1647 open cluster and calibrating object for ``period - luminosity" relation, it is very important to specify the former te{28_Tur92} supposition that this Cepheid is an overtone pulsator, thereas te{28_Sz97} HIPPARCOS data provides fundamental tone for it. The mean Teff and log{g} values determined spectroscopically can confirm this fact, in case that if the Turner's distance value for SZ Tau is true. Nevertheless, the chemical composition analysis shows that SZ Tau is the Cepheid in post red supergiant stage. The evolutionary stage of this object is discussed.