Bibcode
Szabados, L.; Klagyivik, P.
Bibliographical reference
Astronomy and Astrophysics, Volume 537, id.A81, 8 pp.
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1
2012
Journal
Citations
15
Refereed citations
14
Description
Context. Physical and phenomenological properties (radius, luminosity,
shape of the light curve, etc.) of Cepheids strongly depend on the
pulsation period, with the exception of the pulsation amplitude. A
possible factor causing a wide range of pulsation amplitudes might be
the different atmospheric metallicities of individual Cepheids.
Aims: We studied the influence exerted by the atmospheric iron content,
[Fe/H], on the pulsational amplitude of Galactic Cepheids.
Methods: We searched for correlations between the [Fe/H] value and both
the observed amplitudes and amplitude related parameters.
Results: The amplitude of the Cepheid pulsation slightly decreases with
increasing iron abundance. This effect is more pronounced for the radial
velocity variations and for the shorter pulsation periods. The
wavelength dependence of photometric amplitudes is also found to be
sensitive to the metallicity. Some of these effects are not consequences
of differential line blanketing. Based on the calibrations of the
metallicity sensitivity relationships, we derived photometric iron
abundance for 21 Galactic Cepheids. The dichotomic behaviour dividing
Galactic Cepheids that pulsate in the fundamental mode into short- and
long-period groups at the period of 10d.7 can be noticed in
some diagrams that show metallicity-related dependences.
Conclusions: We confirm that variety in atmospheric metallicity in
Cepheids contributes to the finite range of pulsation amplitudes at a
given period. Effects of metallicity on the amplitudes revealed from
observational data and the occurrence of the dichotomy also derived from
phenomenological data have to be confirmed by appropriate theoretical
models of stellar structure and pulsation.