Line profile variations in the δ Scuti star FG Virginis: A high number of axisymmetric modes*
INAF – Osservatorio Astronomico di Brera, Via E. Bianchi 46 23807 Merate, Italy
Corresponding author: L. Mantegazza, firstname.lastname@example.org
Accepted: 26 September 2002
Five consecutive nights of high resolution spectroscopic observations of the δ Scuti star FG Vir allowed us to analyze the radial velocity and line profile variations induced by non-radial multi-mode pulsations. Ten modes were detected. All of them have a photometric counterpart (Breger et al. [CITE]). Preliminary identifications have been performed by means of the simultaneous fit of line-profile and light variations. Most of these modes have an axisymmetric character (), one is retrograde (9.20 cd-1, ) and one is prograde with a relatively high order (21.55 cd-1, , ). The more accurate results regard the dominant mode (12.72 cd-1) which is axisymmetric with . In this case we were able to obtain reliable estimates of its physical characteristics. The analysis of our data tends to support the idea that the stellar rotation axis probably has a rather low inclination (about ): this is probably the reason for the high number of observed axisymmetric modes. Hence, since the measured is 20.7 km s-1, we deduce that the rotation velocity should be around 80 km s-1 and the rotational period about 1.5 d.
Key words: stars: individual: FG Vir / stars: oscillations / stars: variables: δ Sct / techniques: spectroscopic
© ESO, 2002