Physical Parameters of Some Close Binaries: ET Boo, V1123 Tau, V1191 Cyg, V1073 Cyg and V357 Peg

With the aim of providing new and up-to-date absolute parameters of some close binary systems, new BVR CCD photometry was carried out at the Ankara University Observatory (AUG) for five eclipsing binaries, ET Boo, V1123 Tau, V1191 Cyg, V1073 Cyg and V357 Peg between April, 2007 and October, 2008. In this paper, we present the orbital solutions for these systems obtained by simultaneous light and radial velocity curve analyses. Extensive orbital solution and absolute parameters for ET Boo system were given for the first time through this study. According to the analyses, ET Boo is a detached binary while the parameters of four remaining systems are consistent with the nature of contact binaries. The evolutionary status of the components of these systems are also discussed by referring to their absolute parameters found in this study.Comment: this accepted paper will be published in New Astronom

Times of Minima of Some Eclipsing Binaries

We present new times of minima in the light curves of some eclipsing binarie

Meteorological monitoring system of TÜBI·TAK National Observatory

A custom meteorological monitoring system was constructed to reliably monitor the meteorological parameters of the site of TÜBI·TAK National Observatory (TÜBI·TAK: The Scientific and Technical Research Council of Turkey). The site is located on a mountain top known as Bakirlitepe about 50 km west of the Antalya City at a height of 2547m. The system has software (C-based data acquisition/archiving structure and PHP based WEB monitoring support) and micro-controller based control electronics, fiber based custom designed encoder sensors (for wind speed and direction) and transmission lines using fiberoptic to RS232 transcievers. The constructed system can be used in any robotic telescope project for data monitoring and alert system creation

Dome automation of the RTT150 Russian-Turkish telescope building at TÜBI·TAK National Observatory

[No abstract available

Monitoring spots via the TESS data strengthened by the ETV behaviour: An investigation on the contact binary PP Lac

In this study we aim to reveal the starspot behaviour in the contact binary PP Lac, using the clues from the eclipse timing variation (ETV) nature of the system, obtained from the TESS data. In this context, we performed simultaneous ground-based light and radial velocity curves analysis and calculated the absolute physical and orbital parameters of the system. These parameters were then used during the light curve analysis of the TESS data for a detailed spot modelling. We considered three different spot models with: a single spot, two overlapping spots and two non-overlapping spots. The validity of each model was tested by comparing the ETV behaviour with the observed eclipse timings. The ETVs predicted by the overlapping and non-overlapping two-spot models both describe well the ETVs observed in the TESS data. In addition, the results from two-spot models indicate anti-correlated variations of spot sizes and spot longitudes throughout the TESS data time-span, whereas the longitudinal variations exhibit almost the same variation characteristics with the eclipse timings of the system. These findings imply that the longitudinal variation of spots predominantly affect the TESS-ETV behaviour of PP Lac. We conclude that the most likely explanation for light variation without eclipses and the TESS ETV behaviour in PP Lac is the presence of two high-latitude spots (or group of spots) located on the surface of the secondary component. With the help of the orbital stability tests and considering Applegate's mechanism, we found that the most plausible explanation for the two cyclic period variations seen on the overall ETV behaviour of the system is a combination of the magnetic activity cycle and the presence of a third body. © 2023 Elsevier B.V

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