The frequency analysis of low amplitude Scuti stars - V. HD 188520

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...

A photometric monitoring of bright high - amplitude δ Scuti stars I . The double - mode pulsation of V 567 Ophiuchi

We present the first results of an observational project, which addresses the period changing behaviour of a sample of high-amplitude δ Scuti stars. In this paper we discuss the double-mode nature of V567 Ophiuchi. It was observed on 15 nights in two consecutive years in order to resolve the long-standing ambiguity related to its secondary period. A frequency analysis of almost 5000 individual ...

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