Related papers: Spot evolution in the eclipsing binary CoRoT 10589…
The Qatar-2 transiting exoplanet system was recently observed by the {\it Kepler} telescope as part of {\it K2} Campaign 6. The photometric time series has one-minute time sampling and a precision of about 690~ppm, after filtering out…
In this work we present a model of two young eclipsing binaries in the Orion Complex. Both heavily spotted, they present radii and temperatures that are in disagreement with the predictions of standard stellar models. 2M05-06 consists of…
We present a photometric, spectroscopic, asteroseismic, and evolutionary analysis of the Algol-type eclipsing binary KIC 12268220. We find the O'Connell effect and anticorrelated eclipse timing variations in the Kepler light curve,…
We describe the discovery of a 0.68+0.52 solar mass eclipsing binary (EB) with an 8.4-day orbital period, found through a systematic search of ten fields of the Trans-atlantic Exoplanet Survey (TrES). Such long-period low-mass EBs…
Spectroscopic follow-up of dozens of transiting planets has revealed the degree of alignment between the equators of stars and the orbits of the planets they host. Here we determine a method, applicable to spotted stars, that can reveal the…
We present surface spot maps of the K2V primary star in the pre-cataclysmic variable binary system, V471 Tau. The spot maps show the presence of large high latitude spots located at the sub-white dwarf longitude region. By tracking the…
Aims: Time series of high-resolution spectra of the late B-type star HD 11753 exhibiting HgMn chemical peculiarity are used to study the surface distribution of different chemical elements and their temporal evolution. Methods:…
(Abridged) We present spectroscopic and photometric observations of the eclipsing system V1061 Cyg (P = 2.35 days). We show that it is a hierarchical triple in which the third star is visible in the spectra. We combine the radial velocities…
The new photometric space-borne survey missions CoRoT and Kepler will be able to detect minute flux variations in binary stars due to relativistic beaming caused by the line-of-sight motion of their components. In all but very short period…
To detect additional bodies in binary systems, we performed a potent approach of orbital period variation analysis. In this work, we present 90 new mid-eclipse times of a short-period eclipsing binary system. Observations were made using…
We discuss the detectability of gravitationally bounded pairs of gas-giant planets (which we call "binary planets") in extrasolar planetary systems that are formed through orbital instability followed by planet-planet dynamical tides during…
We present the results of a study of differential rotation on the K2 IV primary of the RS CVn binary II Pegasi (HD 224085) performed by inverting light curves to produce images of the dark starspots on its surface. The data were obtained in…
For seven decades, the widely held view has been that the formation, the migration and the decay of short-lived starspots explain the constantly changing light curves of chromospherically active stars. Our hypothesis is that these deceptive…
Double-close-binary quadruples (2+2 systems) are hierarchical systems of four stars where two short-period binary systems move around their common center of mass on a wider orbit. Using Gaia Early Data Release 3, we search for comoving…
Kepler-30 is a unique target to study stellar activity and rotation in a young solar-like star accompanied by a compact planetary system. We use about 4 years of high-precision photometry collected by the Kepler mission to investigate the…
Aims. The CoRoT space mission continues to photometrically monitor about 12 000 stars in its field-of-view for a series of target fields to search for transiting extrasolar planets ever since 2007. Deep transit signals can be detected…
The complexity of composite spectra of close binary star system makes study of the spectra of their component stars extremely difficult. For this reason there exists very little information on the photospheric chemical composition of stars…
Brightness inhomogeneities in the stellar photosphere (dark spots or bright regions) affect the measurements of the planetary transmission spectrum. To investigate the star spots of the M dwarf GJ 1214, we conducted a multicolor photometric…
We present the results of spectroscopic observations of two eclipsing WR+OB-type systems - CQ Cep and CX Cep, performed in 2020-2023 with a low-resolution slit spectrograph TDS ($\lambda\lambda= 3660-7410$\AA, $R = 1300-2500$) on 2.5-m…
DQ Tau is a young low-mass spectroscopic binary, consisting of two almost equal-mass stars on a 15.8 d period surrounded by a circumbinary disk. Here, we analyze DQ Tau's light curves obtained by Kepler K2, the Spitzer Space Telescope, and…