A&A Supplement series, Vol. 121, February 1991, 343-368
Received February 29; accepted June 3, 1996
C. Schrijvers
- J.H. Telting
- C. Aerts
- E. Ruymaekers
- H.F. Henrichs
Send offprint request: Coen Schrijvers, Internet: coen@astro.uva.nl
Astronomical Institute Anton Pannekoek, University
of Amsterdam, and Center for High Energy Astrophysics,
Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
Instituut voor Sterrenkunde, Katholieke Universiteit Leuven,
Celestijnenlaan 200 B, B-3001 Heverlee, Belgium
St. Antoniusstraat 139, B-8500 Kortrijk, Belgium
We present a useful formulation of the surface-velocity field of a
rotating, adiabatically pulsating star, which accounts for the effects
of the Coriolis force. We use this model to investigate the observable
spectroscopic characteristics of non-radial pulsations. We
calculate time series of absorption line profiles in a carefully
chosen domain of parameter space. Only mono-periodic spheroidal modes
are investigated; atmospheric changes due to the pulsation are
neglected. The line-profile variations, as well as their behavior
inferred from two well-defined diagnostics, are presented in
two-dimensional parameter grids.
We show that the intensity variations in time series of theoretical
spectra, at each position in the line profile, cannot be described by
a single sinusoid: at least one harmonic sinusoid needs to be
included. Across the line profile the relative amplitudes and phases
of these sinusoids vary independently. The blue-to-red phase
difference found at the main pulsation frequency turns out to be an
indicator of the degree 
, rather than the azimuthal order
|m|; the phase difference of the variations with the first
harmonic frequency is an indicator of |m|. Hence, the evaluation
of the variability at the harmonic frequency can improve the results
derived from an analysis of observed line profiles.
We find, that if line-profile variations at the line center dominate
over the variations in the line wings, this does not give conclusive
information on the ratio of the horizontal to the vertical pulsational
surface motions.
Tesseral modes, when observed at not too high inclinations, are as
much capable of producing considerable line-profile variations as
sectoral modes.
We find that, within the limits of our model, the effects of rotation
on the appearance of the line-profile variations are important for
low-degree sectoral modes, and for the sub-class of the tesseral
modes with 
an even number.
keywords: line: profiles -- stars: oscillations, rotation --
stars: variable: 
Sct stars; others