The frequency analysis of low-amplitude Scuti stars - III. HD 8781

Incidence of high-amplitude δ Scuti type variable stars

An order-of-magnitude estimate for the incidence of high-amplitude δ Scuti-type variable stars (HADS) in the δ Scuti area of the H-R diagram is calculated. Using a model for the stellar distribution in the Milky Way, we calculate the number of stars that are expected to fall in the δ Scuti area of the H-R diagram within the magnitude range and sky coverage of the ROTSE Survey for Variables I (R...

Simultaneous intensive photometry and high resolution spectroscopy of δ Scuti stars III . Mode identifications and physical calibrations in HD 2724 ⋆

On the basis of our new simultaneous photom-etry and spectroscopy (885 uvby differential measurements in 11 nights and 154 spectrograms of the FeIIλ4508 region in 5 nights), we can detect 12 probable periodicities in the variability pattern of this star, determining the frequencies of 7 without any ambiguity. Through a direct fit of pul-sational models to our data, we estimate the inclination o...

Frequency analysis of δ Scuti and RR Lyrae stars in the OGLE - 1 database

We discuss the results of a systematic search for multi-periodic pulsations in Galactic Bulge δ Scuti and RR Lyrae stars. Six " normal " double-mode variables pulsating in two radial modes have been identified (5 δ Scuti-type and 1 RR Lyrae-type). In 37 RR Lyrae stars secondary periodicities very close to the primary pulsation frequency have been detected. These periodicities correspond to nonr...

Line profile analysis of the δ Scuti star HD 2724≡BB Phe: mode identification and amplitude variations

The line profile variations of the δ Scuti star HD 2724≡BB Phe were studied on the basis of new 189 high– resolution spectrograms covering 52 hours of observations on a baseline of 8.3 days. By combining these results with those of a previous campaign 13 pulsation modes were identified: 5 of them are both photometric and spectroscopic, 3 are purely spectroscopic and 5 purely photometric. For th...

IRAS Observations of Scuti Stars