Low mass stellar companions around four giant stars

We present three low-mass and one solar mass companions found around four intermediate-mass giants HD1695, HD120235, HD145316 and HD200004 from precise radial velocity measurements using the 1.5 m Russian-Turkish Telescope (RTT150) at the TÜBITAK National Observatory of Turkey (TUG). The stellar parameters, which are effective temperature (Teff), surface gravity (logg) and metallicity ([Fe/H]), as well as rotational velocity (vsini) are obtained from spectral analysis. From the estimated stellar masses, the orbital parameters of the companions are also derived. We find two types of Keplerian solutions for the companion of HD120235: (1) periods 5522 days and eccentricity of e∼0.93, and (2) periods 1566 days and eccentricity of e∼0.83. From the abundances analysis HD1695 is found to be a metal-rich star with [Fe/H]>0.1, while HD200004 is a metal poor star with [Fe/H]<-0.2. The other two stars, HD120235 and HD145316, have solar-like abundances with [Fe/H]∼0.0. Our stellar parameters and orbital solutions show that all of these stars are evolved intermediate-mass giants. © 2014 Elsevier B.V. All rights reserved

PHOTOMETRIC, SPECTROSCOPIC, and ORBITAL PERIOD STUDY of THREE EARLY-TYPE SEMI-DETACHED SYSTEMS: XZ AQL, UX HER, and at PEG

In this paper, we present a combined photometric, spectroscopic, and orbital period study of three early-type eclipsing binary systems: XZ Aql, UX Her, and AT Peg. As a result, we have derived the absolute parameters of their components and, on that basis, we discuss their evolutionary states. Furthermore, we compare their parameters with those of other binary systems and with theoretical models. An analysis of all available up-to-date times of minima indicated that all three systems studied here show cyclic orbital changes; their origin is discussed in detail. Finally, we performed a frequency analysis for possible pulsational behavior, and as a result we suggest that XZ Aql hosts a δ Scuti component. © 2016. The American Astronomical Society. All rights reserved

The absolute parameters of the detached eclipsing binary V482 per

We present the results of a spectroscopic, photometric and orbital period variation analysis of the detached eclipsing binary V482 Per. We derived the absolute parameters of the system (M1 = 1.51 M, M2 = 1.29 M, R1 = 2.39 R, R2 = 1.45 R, L1 = 10.15 L, L2 = 3.01 L) for the first time in literature, based on an analysis of our own photometric and spectroscopic observations. We confirm the nature of the variations observed in the system&apos;s orbital period, suggested to be periodic by earlier works. A light time effect due to a physically bound, star-sized companion (M3 = 2.14 M) on a highly eccentric (e = 0.83) orbit, seems to be the most likely cause. We argue that the companion can not be a single star but another binary instead. We calculated the evolutionary states of the system&apos;s components, and we found that the primary is slightly evolving after the main sequence, while the less massive secondary lies well inside it. © 2015 Elsevier Ltd. All rights reserved

Low mass stellar companions around four giant stars

We present three low-mass and one solar mass companions found around four intermediate-mass giants HD1695, HD120235, HD145316 and HD200004 from precise radial velocity measurements using the 1.5 m Russian-Turkish Telescope (RTT150) at the TÜBITAK National Observatory of Turkey (TUG). The stellar parameters, which are effective temperature (Teff), surface gravity (logg) and metallicity ([Fe/H]), as well as rotational velocity (vsini) are obtained from spectral analysis. From the estimated stellar masses, the orbital parameters of the companions are also derived. We find two types of Keplerian solutions for the companion of HD120235: (1) periods 5522 days and eccentricity of e∼0.93, and (2) periods 1566 days and eccentricity of e∼0.83. From the abundances analysis HD1695 is found to be a metal-rich star with [Fe/H]>0.1, while HD200004 is a metal poor star with [Fe/H]<-0.2. The other two stars, HD120235 and HD145316, have solar-like abundances with [Fe/H]∼0.0. Our stellar parameters and orbital solutions show that all of these stars are evolved intermediate-mass giants. © 2014 Elsevier B.V. All rights reserved

Low mass stellar companions around four giant stars

We present three low-mass and one solar mass companions found around four intermediate-mass giants HD1695, HD120235, HD145316 and HD200004 from precise radial velocity measurements using the 1.5 m Russian-Turkish Telescope (RTT150) at the TÜBITAK National Observatory of Turkey (TUG). The stellar parameters, which are effective temperature (Teff), surface gravity (logg) and metallicity ([Fe/H]), as well as rotational velocity (vsini) are obtained from spectral analysis. From the estimated stellar masses, the orbital parameters of the companions are also derived. We find two types of Keplerian solutions for the companion of HD120235: (1) periods 5522 days and eccentricity of e∼0.93, and (2) periods 1566 days and eccentricity of e∼0.83. From the abundances analysis HD1695 is found to be a metal-rich star with [Fe/H]>0.1, while HD200004 is a metal poor star with [Fe/H]<-0.2. The other two stars, HD120235 and HD145316, have solar-like abundances with [Fe/H]∼0.0. Our stellar parameters and orbital solutions show that all of these stars are evolved intermediate-mass giants. © 2014 Elsevier B.V. All rights reserved

Low mass stellar companions around four giant stars

We present three low-mass and one solar mass companions found around four intermediate-mass giants HD1695, HD120235, HD145316 and HD200004 from precise radial velocity measurements using the 1.5 m Russian-Turkish Telescope (RTT150) at the TÜBITAK National Observatory of Turkey (TUG). The stellar parameters, which are effective temperature (Teff), surface gravity (logg) and metallicity ([Fe/H]), as well as rotational velocity (vsini) are obtained from spectral analysis. From the estimated stellar masses, the orbital parameters of the companions are also derived. We find two types of Keplerian solutions for the companion of HD120235: (1) periods 5522 days and eccentricity of e∼0.93, and (2) periods 1566 days and eccentricity of e∼0.83. From the abundances analysis HD1695 is found to be a metal-rich star with [Fe/H]>0.1, while HD200004 is a metal poor star with [Fe/H]<-0.2. The other two stars, HD120235 and HD145316, have solar-like abundances with [Fe/H]∼0.0. Our stellar parameters and orbital solutions show that all of these stars are evolved intermediate-mass giants. © 2014 Elsevier B.V. All rights reserved

The Blazhko effect of RR lyrae in 2003-2004

Aims. Extensive photometry of RR Lyr was obtained over a 421-day interval in 2003-2004, covering more than 10 Blazhko cycles in a multisite campaign. The length and density of this data set allow for a detailed analysis. Methods. We used Fourier techniques to study RR Lyr&apos;s behavior over the pulsation and the Blazhko cycle. We propose a two-frequency model for decomposing the frequency spectrum. Results. The light variations were fitted with the main radial frequency, its harmonics up to 11th order, and the detected triplet frequencies. No significant quintuplet components were found in the frequency spectrum. Given the total time span of the measurements, we can now unambiguously conclude that the Blazhko period has become notably shorter than the previously known value of 40.8 days, whereas the main pulsation period remained roughly the same. Changes in the modulation period have been reported for other well-studied Blazhko variables. They challenge the explanations for the Blazhko effect which link the modulation period directly to the rotation period. The new photometry reveals an interval in the pulsation cycle of RR Lyr during which the star&apos;s intensity barely changes over the Blazhko cycle. This interval occurs during the infalling motion and between the supposed phases of the early and the main shock. The data also permit a more detailed study of the light curve shape at different phases in the Blazhko period through Fourier parameters. © ESO 2006

The Blazhko effect of RR lyrae in 2003-2004

Aims. Extensive photometry of RR Lyr was obtained over a 421-day interval in 2003-2004, covering more than 10 Blazhko cycles in a multisite campaign. The length and density of this data set allow for a detailed analysis. Methods. We used Fourier techniques to study RR Lyr's behavior over the pulsation and the Blazhko cycle. We propose a two-frequency model for decomposing the frequency spectrum. Results. The light variations were fitted with the main radial frequency, its harmonics up to 11th order, and the detected triplet frequencies. No significant quintuplet components were found in the frequency spectrum. Given the total time span of the measurements, we can now unambiguously conclude that the Blazhko period has become notably shorter than the previously known value of 40.8 days, whereas the main pulsation period remained roughly the same. Changes in the modulation period have been reported for other well-studied Blazhko variables. They challenge the explanations for the Blazhko effect which link the modulation period directly to the rotation period. The new photometry reveals an interval in the pulsation cycle of RR Lyr during which the star's intensity barely changes over the Blazhko cycle. This interval occurs during the infalling motion and between the supposed phases of the early and the main shock. The data also permit a more detailed study of the light curve shape at different phases in the Blazhko period through Fourier parameters. ESO 2006