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TwitterDOI: 10.1051/0004-6361/200912554
Notes on disentangling of spectra
II. Intrinsic line-profile variability due to Cepheid pulsations
P. Hadrava1, M. Šlechta2, and P. Škoda21 Astronomical Institute, Academy of Sciences, Boční II 1401, 141 31 Praha 4, Czech Republic
e-mail: had@sunstel.asu.cas.cz
2 Astronomical Institute, Academy of Sciences, Fričova 298, 251 65 Ondřejov, Czech Republic
e-mail: [slechta;skoda]@sunstel.asu.cas.cz
Received 22 May 2009 / Accepted 2 August 2009
Abstract
Context. The determination of pulsation velocities from observed spectra of
Cepheids is needed for the Baade-Wesselink calibration of these
primary distance markers.
Aims. The applicability of the Fourier-disentangling technique
for the determination of pulsation velocities of Cepheids and other
pulsating stars is studied.
Methods. The KOREL-code was modified to enable fitting of free parameters
of a prescribed line-profile broadening function corresponding to
the radial pulsations of the stellar atmosphere. It was applied to
spectra of 
Cep in the H-alpha region observed with the Ondřejov
2-m telescope.
Results. The telluric lines were removed using template-constrained
disentangling, phase-locked variations of line-strengths were measured
and the curves of pulsational velocities obtained for several
spectral lines. It is shown that the amplitude and phase of the
velocities and line-strength variations depend on the depth of line
formation and the excitation potential.
Conclusions. The disentangling of pulsations in the Cepheid spectra may be
used for distance determination.
Key words: line: profiles -- techniques: spectroscopic -- stars: variables: Cepheids -- stars: atmospheres
© ESO 2009