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The All-Sky Automated Survey for Supernovae (ASAS-SN) provides long baseline (${\sim}4$ yrs) $V-$band light curves for sources brighter than V$\lesssim17$ mag across the whole sky. We produced V-band light curves for a total of ${\sim}61.5$…
We review ways in which observations of the changing periods of pulsating variable stars can be used to detect and directly measure their evolution. We briefly describe the two main techniques of analysis -- (O-C) analysis and wavelet…
During the last two years we have received long time-series photometric observations of bright (V mag < 8) main-sequence A- and B-type stars observed by the NASA TESS spacecraft and the Austria-Poland-Canada BRITE satellites. Using TESS…
We present analysis of the large sample of variable red giants from the Large and Small Magellanic Clouds detected during the second phase of the Optical Gravitational Lensing Experiment (OGLE-II) and supplemented with OGLE-III photometry.…
We present the results of a multi-site photometric campaign carried out in 2004-2008 for the Algol-type eclipsing binary system CT Her, the primary component of which shows Delta Scuti-type oscillations. Our data consist of differential…
As a result of the search among about 11 000 stars from the public ASAS-3 database, we report detection of pulsating components in eleven eclipsing binaries. In particular, we have found three classical Algols, MX Pav, IZ Tel, and VY Mic,…
AST3-1 is the second-generation wide-field optical photometric telescope dedicated to time domain astronomy at Dome A, Antarctica. Here we present the results of $i$ band images survey from AST3-1 towards one Galactic disk field. Based on…
Convective envelopes in stars on the main sequence are usually connected only with stars of spectral types F5 or later. However, observations as well as theory indicate that the convective outer layers in earlier stars, despite being…
All stars in the Kepler field brighter than 12.5 magnitude have been classified according to variability type. A catalogue of {\delta} Scuti and {\gamma} Doradus stars is presented. The problem of low frequencies in {\delta} Sct stars,…
Context. Plaskett's star (HD47129) is a very massive O-star binary in a post Roche-lobe overflow stage. CoRoT observations of this system revealed photometric variability with a number of frequencies. Aims. The aim of this paper is to…
(abridged version) Context : The detection of bright, hard, and variable X-ray emission in Tr16-22 prompted spectropolarimetric observations of this star, which in turn led to the discovery of a surface magnetic field. Aims : We want to…
The (magnetic) chemically peculiar (CP) stars of the upper main sequence are well-suited laboratories for investigating the influence of magnetic fields on the stellar surface because they produce abundance inhomogeneities (spots), which…
Time-resolved low resolution Hubble Space Telescope ultraviolet spectra together with ground-based optical photometry and spectra are used to constrain the temperatures and pulsation properties of six cataclysmic variables containing…
The Kepler spacecraft is providing time series of photometric data with micromagnitude precision for hundreds of A-F type stars. We present a first general characterization of the pulsational behaviour of A-F type stars as observed in the…
We present results from the first two quarters of a survey to search for pulsations in compact stellar objects with the Kepler spacecraft. The survey sample and the various methods applied in its compilation are described, and spectroscopic…
We present a new catalog of 1575 contact binary stars fainter than I=18 mag identified in OGLE-I database in the selected directions toward the Galactic bulge and the Galactic bar. For completeness we recall here also the objects from the…
The pulsating white dwarf star PY Vul (G~185-32) exhibits pulsation modes with peculiar properties that set it apart from other variable stars in the ZZ Ceti (DAV) class. These peculiarities include a low total pulsation amplitude, a mode…
The Optical Gravitational Lensing Experiment (OGLE), originally designed to search for microlensing events, provides a rich and uniform data set suitable for studying the variability of certain types of objects. We used the OGLE data to…
Complex periodic variables (CPVs) are stars that exhibit highly structured and periodic optical light curves. Previous studies have indicated that these stars are typically disk-free pre-main-sequence M dwarfs with rotation periods ranging…
As part of the NASA Kepler Guest Observer program, we requested and obtained long-cadence data on about 2700 faint (magnitude 14-16) Kepler stars with effective temperatures and surface gravities that lie near or within the pulsation…