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Astron. Astrophys. 342, 453-463 (1999)

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Line-profile variations due to adiabatic non-radial pulsations in rotating stars

IV. The effects of intrinsic profile variations on the IPS diagnostics

C. Schrijvers 1 and J.H. Telting 2

1 Astronomical Institute Anton Pannekoek, University of Amsterdam, and Center for High Energy Astrophysics, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
2 Isaac Newton Group of Telescopes, ASTRON/NFRA, Apartado 321, E-38780 Santa Cruz de La Palma, Spain

Received 14 August 1998 / Accepted 20 October 1998

Abstract

We calculate time series of Doppler-broadened line-profiles of rotating stars that exhibit non-radial pulsations. We investigate the variability of such line profiles for cases in which variations of the intrinsic line-profile cannot be neglected. To study the effects of atmospheric changes on the line-profile variability we include: (1) local changes of the surface brightness, (2) local changes in the equivalent width of the intrinsic line profile, and (3) a non-adiabatic phase lag between the radial pulsational displacement and the surface-temperature perturbations.

We parameterize these three effects to extend the study presented in Paper I . The variability is analyzed by means of amplitude and phase diagrams obtained from Fourier transforms at each point of the line profile. One of our findings is that an asymmetry in the distribution of amplitude across the line profile can be caused by non-adiabaticity of the contributing temperature variations.

We perform Monte-Carlo simulations to investigate the correlation between the phase diagrams and the [FORMULA] and m values of modes, in cases with line-profile variability that is dominated by the variable atmospheric properties. The retrieval of [FORMULA] turns out to be similarly successful as in Paper II , where the variability was dominated by the surface-velocity field. We also find that harmonic variability is specific for pulsational surface-velocity fields rather than for variations of the surface temperature.

Key words: line: profiles – methods: data analysis – stars: early-type – stars: oscillations – stars: rotation – stars: variables: ffi sct

Correspondence to: coen@astro.uva.nl

This article contains no SIMBAD objects.

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© European Southern Observatory (ESO) 1999

Online publication: February 22, 1999
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