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OHP Preprint No. 106 : Study of
Puppis
A spectroscopic study of the Scuti star
Puppis
P. Mathias1, D. Gillet2, C. Aerts3,
M.G. Breitfellner4
1Observatoire de la Côte d'Azur, Département Fresnel, U.M.R. 6528,
BP 4229, F-06304 Nice Cedex 04, France
2Observatoire de Haute Provence (CNRS)
F-04870 Saint Michel l'Observatoire, France
e-mail: gillet@obs-hp.fr
3Instituut voor Sterrenkunde, Katholieke Universiteit Leuven,
Celestijnenlaan 200B, B-3001 Heverlee, Belgium
4ISO Science Operations, ESA/VILSPA Satellite Tracking Station,
PO Box 50727, E-28080 Madrid, Spain
Astronomy and Astrophysics (in press)
Based on observations obtained at the European Southern Observatory,
Chile
Abstract
We present a spectroscopic analysis of the
Scuti star Pup
on the basis of high resolution data spread over 4 consecutive nights.
Despite the
clearly sinusoidal shape of the radial-velocity curves, cycle-to-cycle
variations are observed. A frequency analysis points towards the already
known
frequency 0=7.098168 c/d assigned to a radial mode and towards
two possible secondary non-radial
oscillations at 1 =7.8 c/d and
2 = 6.3 c/d
of much smaller amplitude.
Using the moment method we confirm that the main
oscillation is a radial mode. The second mode is found to be axisymmetric,
but because of its small
amplitude and our relatively small data set, no more detailed information on
its pulsation parameters could be derived. The third frequency, if real,
corresponds to a non-axisymmetric mode.
The running wave effect may be present between the Fe I and
H
lines, the latter being late by about 0.5 % of the pulsation period.
No evidence is found in our observed profiles (Ca I, Fe I,
H)
for a shock wave mechanism as previously suggested by Dravins et al. (1977).
New observations are required to confirm the
presence of a period-dependent shock wave which should be of weak intensity.
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