1997A&A...327.1077M

We present a spectroscopic analysis of the δ Scuti star ρ 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 ν₀=7.098168c/d assigned to a radial mode and towards two possible secondary non-radial oscillations at ν₁=7.8c/d and ν₂=6.3c/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 FeI and Hα lines, the latter being late by about 0.5% of the pulsation period. No evidence is found in our observed profiles (CaI, FeI, Hα) for a shock wave mechanism as previously suggested by Dravins et al. (1977A&A....54..381D). New observations are required to confirm the presence of a period-dependent shock wave which should be of weak intensity.