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Triple Eccentric Systems V0345 Lac, YY Sgr, and DR Vul

Wolf M., Zasche P., Kučáková H., Mašek M., Hoňková K., Juryšek J., Paschke A., Šmelcer L., Zejda M.

Acta Astronomica

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2019

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Vol. 69, No. 1

63--78

EN

We present more results of our long-term observational project to analyze the variations of the orbital period for early-type eccentric eclipsing binaries. About sixty new precise mid-eclipse times were measured or derived for three eclipsing binaries, namely V0345 Lac, YY Sgr, and DR Vul. Based on current O-C diagrams, we found in all cases that beside the typical apsidal motion the times of minima show additional cyclical changes likely caused by a third body orbiting the eclipsing pair. The new light curve solution of V0345 Lac results in a moderate orbital eccentricity (e=0.26) of this binary. The periods of apsidal motion are 1580 yr, 295 yr, and 36 yr, respectively. The relativistic contributions to the total apsidal-motion rate are small for all three eccentric binaries - about 5-14%. The third-body orbital periods are relatively short: 24 yr, 19 yr and 66 yr, and the minimal masses of third bodies are: 2.0 M☉, 0.8 M☉, and 7.2 M☉, respectively.

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The Triple Eccentric Systems V974 Cyg, RU Mon, and V456 Oph

Wolf M., Zasche P., Kučáková H., Hoňková K., Juryšek J., Mašek M., Uhlař R., Urbaník M.

Acta Astronomica

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2017

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Vol. 67, No. 3

257--271

EN

We present results of a long-term program for timing the eclipses of eccentric eclipsing binaries. About 40 new precise mid-eclipse times were measured for the eclipsing binary V974 Cyg, RU Mon and V456 Oph. Based on current O-C diagrams, we found in all cases that times of minima besides the typical apsidal motion show additional cyclical changes caused very probably by the third bodies orbiting the eclipsing pair. The periods of apsidal motion are 1470 yr, 361 yr and 22.6 yr, respectively. The period of V456 Oph this is one of the shortest known apsidal-motion periods. The relativistic contributions to the total apsidal-motion rate are significant for V974 Cyg (about 30%) and negligible for RU Mon and V456 Oph (1-2.5%). The third-body orbital periods are relatively short: 30.6 yr, 59.8 yr and 7.4 yr, and their minimal masses are 0.40 M☉, 1.6 M☉, and 0.27 M☉, respectively.

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Ambient fields generated by a laser spark

Rohlena K., Mašek M.

Nukleonika

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2016

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Vol. 61, No. 2

119--124

EN

The electric and magnetic fields surrounding a laser spark formed after an optical breakdown due to a focused nanosecond laser beam in a gaseous environment are examined in order to assess their possible influence on the processes going on in the gas medium, mainly chemical reactions triggered by the spark plasma radiation. The magnetic field is generated by the standard mechanism of crossed electron density and temperature gradients, the electric field is supposed to be produced by the plasma polarization due to its radial expansion across the self-generated magnetic field. A simple model of spark plasma formation near the tip of the focal cone is assumed, with a delayed breakdown, which allows the focused laser light to sweep the whole volume of the forming spark right down to the focal caustic and thus to form a centimeter long plasma cone. In this conical geometry, the value of plasma electric dipole moment is evaluated as a measurable quantity as well as approximate values of the electric and magnetic field near the focal caustic, where they both tend to grow in magnitude.

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2nd generation wobble watercraft

Urbánek M., Jánská D., Mašek M., Folgar Ribadas H., Nový Z.

Journal of Achievements in Materials and Manufacturing Engineering

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2015

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Vol. 73, nr 2

185--189

EN

Purpose: The main objective of the present work was to develop a new type of human-powered watercraft for sports activities on still water bodies, such as reservoirs and lakes. Design/methodology/approach: The power for the watercraft is provided by the body of its operator who sets the propulsion mechanism in oscillating or rocking motion. The oscillating or rocking motion of the mechanism is transmitted to underwater propelling elements. A prototype has been built and tested. A computer model of this craft was constructed using Solidworks 2014 CAD tool and strength verification calculations were carried out in MSC.MARC software. Findings: The prototype consists of a float in the form of a surfboard and a moving mechanism which incorporates a welded high-strength aluminium alloy frame. Great effort was put into finding an appropriate shape of the propelling element. Practical implications: Multiple elements of various shapes and sizes have been tested. Their verification with the aid of CFD analysis in Xflow software was followed by physical testing. Originality/value: Once the suitable type, shape and size of the propelling element were identified, the elements were applied to the craft. Successful testing of these 2nd generation prototypes was completed this year.

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The Study of Triple Systems V949 Cen, V358 Pup and V1055 Sco

Zasche P., Hoňkovà K., Juryšek J., Mašek M.

Acta Astronomica

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2015

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Vol. 65, No. 2

151--168

EN

The systems V949 Cen, V358 Pup, and V1055 Sco are triples comprised of an eclipsing binary orbiting with a distant visual component on a much longer orbit. The first detailed photometric analysis of these interesting systems was performed using also the archival data from Hipparcos, ASAS, SuperWASP, OMC, and Pi of the Sky surveys. The system V358 Pup was also analyzed using the archival ESO spectra and the radial velocities were derived. The analyses of their light curves revealed the physical properties of the eclipsing components, while the interferometric data for these systems obtained during the last century show that the binaries are also weakly gravitationally bounded with the third components on much longer orbits. The photometry was carried out with the robotic telescope FRAM (part of the Pierre Auger Cosmic Ray Observatory), located in Argentina. The BVRI light curves were analyzed with the PHOEBE program, yielding the basic physical parameters of the systems and their orbits. V949 Cen and V358 Pup were found to be detached systems, while V1055 Sco is probably a semi-detached one. V358 Pup shows a slow apsidal motion, while for V1055 Sco we detected some period variation probably due to the third body in the system, which cannot easily be attributed to the close visual companion. Therefore, we speculate that V1055 Sco can be a quadruple system. For V949 Cen a new orbit was computed, having the orbital period of about 855 yr.