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New Photometric and Spectroscopic Observations of the Eclipsing Binary V2080 Cygni

Dimitrov W., Kamiński K., Bąkowska K., Kamińska M. K., Tokarek J., Pawłowski M., Boneva D., Bartczak P., Kwiatkowski T., Schwarzenberg-Czerny A.

Acta Astronomica

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2022

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Vol. 72, No. 1

55--67

EN

We present new spectroscopic and photometric measurements of the eclipsing binary V2080 Cyg. It is a detached system with similar components and an orbital period of 4.9 d. We collected spectroscopic data with two instruments, 1.88 m DDO telescope equipped with Cassegrain spectrograph and 0.5 m PST1 connected to a fiber-fed echell\'e spectrograph. We collected 127 measurements for each component, which significantly increase the number of available radial velocity measurements for the V2080 Cyg system. Obtained masses of the eclipsing components are M1=1.189± 0.007 and M2=1.138±0.007 M☉. We also collected a multicolor photometry. The three-band light curves obtained together with the radial velocity data enabled us to calculate the model of the system. New estimations of the orbital inclination and radii of the components were computed. We obtained as well new times of minima. The O-C diagrams indicate variation, which requires more recent data to be confirmed. The possible existence of a third body could cause a light-time effect in the system. In addition, we analyze the Gaia mission results. V2080 Cyg A has three visual companions. However, according to Gaia parallaxes and proper motions, they cannot be dynamically connected with the eclipsing binary and therefore are background stars.

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Over a Century of δ Ceti Variability Investigation

Śreniawska E., Kamiński K., Kamińska M. K., Tokarek J., Zgórz M.

Acta Astronomica

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2021

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Vol. 71, No. 4

297--310

EN

We present results of a 2014-2018 campaign of radial velocity measurements of δ Ceti. Combining our determination of pulsation period with historical data we conclude that the most likely explanation of observed changes is the presence of a secondary component with a minimum mass of 1.10±0.05 Mo on an orbit with a period of 169±6 yr. Consequently, we revised the intrinsic, evolutionary period change rate to be not larger than 0.018±0.004 s/century, which is significantly lower than previous estimations and is consistent with evolutionary models. We did not find any significant multiperiodic frequencies in radial velocity periodograms such as those reported in the photometric data from the MOST satellite. Using interferometric angular size of δ Ceti from JMMC Stellar Diameters Catalogue we determined several physical parameters of the star with bolometric flux method. They turned out to be consistent with most previous determinations, confirming lower mass and slower evolution of δ Ceti than obtained using different methods.

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Spectroscopy of the Eclipsing Binary BD-00°2862. Possible Multiplicity

Dimitrov W., Żywucka N, Polińska M., Kamiński K., Kamińska M. K.

Acta Astronomica

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2018

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Vol. 68, No. 3

269--284

EN

We present the first spectroscopic analysis of the eclipsing binary BD-00°2862. The All Sky Automated Survey light curves yield orbital period of the system of 2.15 d. The shape of the light curve reveals that the components are almost spherical and the binary is detached. The eclipses depths show significant difference of the components' temperature. We acquired spectra with 0.5-m telescope equipped with an echellé spectrograph. The spectra are dominated by the lines of the more luminous component, which is about five times more luminous than its close companion. Obtained radial velocities together with the light curves enabled us to obtain a model of the system using the Wilson-Devinney method. The mass ratio of the stars is 0.67 and the size of the semi-major axis is 8.6 R⊙. The masses of the eclipsing components are M1=1.08±0.03 M⊙ and M2=0.72±0.02 M⊙. The stars are not evolved and the radii are close to the main sequence values: R1=1.21±0.01 R⊙ and R2=0.71±0.01 R⊙. The evolutionary tracks show that the system is probably on the pre main sequence stage. The photometric parallax yields distance of 131 pc, which is comparable with the one obtained by Gaia mission - 130 pc. We carried out a spectrum analysis for the main component obtaining its temperature of 5600±400 K and the metallicity - [M/H]=-0.30±0.20. The star has a visual companion separated by about 12". The companion has proper motion comparable to the one of the main star. Additionally, its distance based on the trigonometric parallax is equal within errors with the distance of component A. Therefore, the companion is probably a part of the system. Its spectral type is M3 and the estimated mass - about 0.3M⊙.

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GT Ursae Majoris AB - a Possible Quadruple System

Dimitrov W., Tomov T., Kamiński K., Polińska M., Iliev I., Kamińska M. K.

Acta Astronomica

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2018

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Vol. 68, No. 2

141--158

EN

We present the first spectroscopic study of an eclipsing system GT UMa. Our spectra show that the main visual component A is a triple-lined star, which consists of a close eclipsing pair and a farther third component. Radial velocity measurements show evidence of reflex motion. We used Hipparcos and our own R-band light curves for the analysis. These results enabled us to calculate absolute parameters of the eclipsing binary system: 1.37 M⊙ and 1.31 M⊙ and corresponding radii 2.11 R⊙ and 1.63 R⊙. Both eclipsing components are evolved. The orbital period of the eclipsing subsystem is 1.2 d and the semi-major axis - 6.5 R⊙. The wide orbit has low radial velocity amplitude and its parameters are difficult to determine. We obtained a preliminary solution which must be confirmed with future observations. The preliminary period of the wide orbit is 394 d and the lower limit for the semi-major axis - 174 R⊙ (0.81 a.u.). We estimated the mass of the third body to about 1.1 M⊙. Additionally, we investigated the visual companion B. We obtained spectra of this star and measured the radial velocity which is very close to the one of the component A. The proper motions and the parallax are also similar. These are strong arguments that component B is gravitationally bound with the main triple system A.