We review a slightly modified method of eclipse mapping, applicable to mode identification in eclipsing binaries containing a pulsating component. The observed light curve is used by the procedure without removing from it the badly determined eclipsing part.

RZ Cas is an Algol-type eclipsing binary system where the primary component was recently discovered as a δ Set pulsator. A three-continent multisite photometric campaign was carried out during 1999. Preliminary results are reported here indicating a semi-detached system where the secondary fills its Roche lobe. The light curves also suggest a hot spot on the surface of the primary component as a consequence of the impact of the mass stream from the secondary. The pulsational behaviour can be well described with only one frequency.

We present CCD photometric results of the eclipsing binary Y Cam with a pulsating component. The dominant pulsation frequency of 15.0473 c d-1 has not changed over 39 years, but its amplitude decreased to about half. The pulsational properties of the second frequency showed great differences between Broglia & Conconi (1984)’s result and ours.

We have measured the centroid shift of low resolution HST FOC spectra as the dominant star changes from the Cepheid to the hot companion. With this approach we have resolved the AW Per system and marginally resolved the U Aql system.

Baade-Wesselink radii for dwarf Cepheids (High Amplitude Delta Scuti stars) can give luminosities and distances independent of the classical Cepheid distance scale. Using optical and IR photometry together with precision radial velocities, the authors have obtained radii and luminosities for 7 stars, and combined these with two from the literature, obtaining results consistent with the luminosities of the 3 dwarf Cepheids with good Hipparcos parallaxes. Classical Cepheids and dwarf Cepheids appear to fit the same PL and PR relations. The results imply ‘bright’ RR Lyrae absolute magnitudes giving an LMC distance modulus of 18.51-18.54, in agreement with the distance derived from classical Cepheids.

The δ Scuti stars are variables found in the instability strip above the zero-age main sequence. Radial and nonradial pulsation modes have been detected in these stars. The large-amplitude variables with asymmetric light curves are radial pulsators. The pulsation periods are found to be in the period range of 0.03 – 0.25 days. Generally, the light amplitudes are small (total range < 0.3 mag), but some fundamental-mode variables reach 0.70 mag. The majority of the variables have light amplitudes <0.10 mag. Population II δ Scuti variables are frequently called SX Phe stars. Many of these variables have been found in globular clusters, where they populate the blue-straggler domain of the color-magnitude diagrams.

We describe two projects currently underway to provide an improved calibration of RR Lyrae luminosities.

RR Lyrae stars (RRL) are a favourite standard candle for globular clusters and other old stellar populations, yet recent absolute magnitude calibrations, MV(RR), span more than 0.2 mag. Precise distance estimates for nearby globular clusters will eventually be available through satellite-based trigonometric parallaxes (Layden, these proceedings), thus providing a resolution to this old problem.

Here, we present a progress report on our high quality time-series photometry of RRL in the nearby globular cluster NGC 3201 - the first obtained for this cluster with a CCD. The resulting light curves provide accurate intensity-mean apparent magnitudes and reddening estimates, which will in turn be used to calibrate MV(RR) once a satellite-based parallax for NGC 3201 is available.

We present new results on a sample of RR Lyrae variables in the bar of the Large Magellanic Cloud (LMC), and report on the first detection of RR Lyrae in the dwarf spheroidal galaxy Leo I. Emphasis is given to the discussion of the distances to these galaxies as derived from their RR Lyrae populations, and of the impact on the “short” and “long” distance scale dichotomy.

Candidate RR Lyrae variables have been identified for the first time in four globular clusters of the Andromeda galaxy (M31). Using HST-WFPC2 archive observations we have found 2, 4, 11 and 8 RR Lyrae variables of both ab and c Bailey types in G11, G33, G64 and G322 (Sargent et al., 1977), respectively. These numbers are quite consistent with the horizontal branch morphology exhibited by the four clusters.

We present new results on RR Lyrae stars and anomalous Cepheids in the Draco dwarf spheroidal galaxy. We have increased the number of double-mode RR Lyrae stars and found three new anomalous Cepheids. With period-magnitude and period-amplitude diagrams, we discuss the Oosterhoff classification of Draco. Contradictory results were found in that Draco appears to contain both Oosterhoff I and II type RR Lyrae populations.

We present some preliminary results based on new observations of the variable stars belonging to the Carina Dwarf Galaxy (DG). Photometric data were collected with the two wide field imagers available at ESO ([email protected].) and CTIO (4m prime focus).

Theoretical period-luminosity and period-luminosity-colour-metallicity relations are used to give distance estimates for the globular cluster M55 from detailed data for 24 SX Phœnicis variables published recently by Pych et al. (2001). With accurate determinations of effective temperatures for the SX Phe stars application of period-luminosity-colour-metallicity relations will lead to improved distances and more secure mode identifications.

Through time-series CCD photometry of the globular cluster M 53, we have discovered eight new SX Phoenicis type stars. All the new SX Phoenicis stars are located in the blue straggler star region in the color-magnitude diagram of M 53. In addition, we have obtained light curves for 45 known RR Lyrae stars.

We have compiled an extensive and up-dated list of SX Phe-type pulsators in globular clusters. In addition, SX Phe variables discovered in the Carina dwarf galaxy and other ones probably belonging to the Sagittarius dwarf galaxy are included. This catalogue is intended to be an up-dated list of all the SX Phe stars, in globular clusters and galaxies, known until now. The stars and their most significant parameters are listed together with references to studies of individual stars and notes for a number of variables. In addition, the references on the discovery for each variable and sources for photometry are also listed. Some relevant distributions are also analysed. The analysis of metal abundances and mean periods shows that both parameters are correlated in the sense that the periods of the variables are longer as the metallicity of the stellar system is higher.

Results of a search for variable stars in the globular cluster M 13 are presented. Comments on the variability of all observed variable or suspected variable stars are given. Five new RR Lyrae stars and one SX Phoenicis star are identified.

During the last several years about a dozen young northern clusters and associations have been observed in our program of searching for B-type variables. As far as B-type pulsators are concerned, we found that (i) young northern open clusters are a few times less abundant in β Cephei stars than the southern ones, (ii) all newly discovered SPB stars seem to be monoperiodic.

We present the results of the multi-color, two-site observing campaign of β Cephei stars in the young open cluster NGC 4755, from 1999 and 2000. More than 200 hours of time-series photometric U, B, V filter data of the variable stars were acquired. We show a table of the detected frequencies and discuss the results.

We present results of a CCD variability search in the field of the young open cluster NGC 7419. This cluster contains a large number of Be stars and almost all of them turned out to be variable. They show mostly irregular variations on different time-scales with ranges up to 0.4 mag in the IC band. The most interesting result is the discovery of short-period variability in some of the Be stars.

Photometric observations of A-F stars in the uvbyβ system have been performed in order to detect γ Doradus variables in open clusters of different ages. In the clusters Praesepe and α Per, several stars show some type of variability but only three of them, KW370 (Praesepe) and HE104 and HE876 (α Per), can be classified as γ Doradus-type pulsators.