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Valašské Meziříčí, Czech Republic

Wolf M.,Charles University | Zasche P.,Charles University | Kucakova H.,Charles University | Vrastil J.,Charles University | And 5 more authors.
Astronomy and Astrophysics | Year: 2016

Aims. As part of our long-term observational project we aim to measure very precise mid-eclipse times for low-mass eclipsing binaries, which are needed to accurately determine their period changes. Over two hundred new precise times of minimum light recorded with CCD were obtained for three eclipsing binaries with short orbital periods: NSVS 01286630 (P = 0d.8), NSVS 02502726 (0d.56), and NSVS 07453183 (0d.37). Methods. O-C diagrams of studied stars were analysed using all reliable timings, and new parameters of the light-time effect were obtained. Results. We derived for the first time or improved the very short orbital periods of third bodies of between one and seven years for all measured low-mass systems. We calculated that the lowest masses of the third components are between those of red and brown dwarfs. The multiplicity of these systems also plays an important role in the precise determination of their physical parameters. This research is part of an ongoing collaboration between professional astronomers and the Czech Astronomical Society, Variable Star and Exoplanet Section. © ESO, 2016. Source


Wolf M.,Charles University | Claret A.,Institute Astrofisica Of Andalucia | Kotkova L.,Czech Republic Astronomical Institute | Kucakova H.,VSB - Technical University of Ostrava | And 4 more authors.
Astronomy and Astrophysics | Year: 2010

Context: The study of apsidal motion in detached eclipsing binary systems is known to be an important source of information about stellar internal structure as well as the possibility of verifying of General Relativity outside the Solar System. Aims: As part of the long-term Ondřejov and Ostrava observational projects, we aim to measure precise times of minima for eccentric eclipsing binaries, needed for the accurate determination of apsidal motion, providing a suitable test of the effects of General Relativity. Methods: About seventy new times of minimum light recorded with photoelectric or CCD photometers were obtained for ten eccentric-orbit eclipsing binaries with significant relativistic apsidal motion. Their O-C diagrams were analysed using all reliable timings found in the literature, and new or improved elements of apsidal motion were obtained. Results: We confirm very long periods of apsidal motion for all systems. For BF Dra and V1094 Tau, we present the first apsidalmotion solution. The relativistic effects are dominant, representing up to 100% of the total observable apsidal-motion rate in several systems. The theoretical and observed values of the internal structure constant k2 were compared for systems with lower relativistic contribution. Using the light-time effect solution, we predict a faint third component for V1094 Tau orbiting with a short period of about 8 years. © 2010 ESO. Source


Wolf M.,Charles University | Kucakova H.,VSB - Technical University of Ostrava | Hynek T.,VSB - Technical University of Ostrava | Smelcer L.,Observatory Valasske Mezirici
Astronomy and Astrophysics | Year: 2010

The variable star AO Mon is a relatively bright but seldom investigated early-type eccentric eclipsing binary. Thirty new eclipses were measured as a part of our long-term observational project or derived from previous measurements. Based on a new solution of the current O-C  diagram, we found for the first time a rapid apsidal advance superimposed with a light-time effect caused by a third unseen body in the system. Their short periods are 33.8 years and 3.6 years for the apsidal motion and the third-body circular orbit, respectively. The observed internal structure constant was derived to be log k2, obs =-2.23, which is close to the theoretically expected value. The relativistic as well as the third-body effects on the apsidal advance are negligible, as they are only about 3% of the total apsidal motion rate. © ESO, 2010. Source


Wolf M.,Charles University | Smelcer L.,Observatory Valasske Mezirici | Kucakova H.,VSB - Technical University of Ostrava | Hynek T.,VSB - Technical University of Ostrava | And 3 more authors.
New Astronomy | Year: 2010

V381 Cas is a relatively bright and early-type eclipsing binary system. Several new times of its eclipses were measured as part of our long-term observational project of eccentric eclipsing binaries. Based on a current O-C diagram solution, we found for the first time that its orbit is slightly eccentric (e = 0.025) and shows a very rapid apsidal advance with short period of about 20 years only. The relativistic and third body effects are negligible, being about 3% of the total apsidal motion rate. © 2010 Elsevier B.V. All rights reserved. Source


Wolf M.,Charles University | Lehky M.,Observatory and Planetarium Hradec Kralove | Smelcer L.,Observatory Valasske Mezirici | Kucakova H.,VSB - Technical University of Ostrava | Kocian R.,VSB - Technical University of Ostrava
New Astronomy | Year: 2011

Several new precise times of eclipses were measured for eclipsing binary CG Aur as a part of our long-term observational project for studying eclipsing binaries with an eccentric orbit. Based on a current O - C diagram, we found for the first time that its orbit is slightly eccentric (e = 0.124) and that times of minima besides the slow apsidal motion show very rapid changes with a period about 700 days only, caused very probably by the third body orbiting the eclipsing pair. The relativistic contribution to the total apsidal-motion rate is significant being about 33%. © 2011 Elsevier B.V. All rights reserved. Source

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