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Issue A&A
Volume 507, Number 1, November III 2009
Page(s) 397 - 404
Section Stellar atmospheres
DOI http://dx.doi.org/10.1051/0004-6361/200912554
Published online 08 September 2009

A&A 507, 397-404 (2009)
DOI: 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. Škoda2

1  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 $\delta$ 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


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