B. Gürol

Multiband Photometric and Spectroscopic Analysis of HV Cnc

In this paper, radial velocity and VI- and JHKS - (Two Micron All Sky Survey) band photometric data of the detached system HV Cnc have been analyzed. The primary component of HV Cnc, which is a member of the M67 cluster, is suspected to be either a blue straggler or turn-off star. The system is a single-lined spectroscopic binary and its light curve shows a total eclipse. Spectroscopic observations of the system revealed the third component, which shows contribution to the total light of the system. Light curve and radial velocity data have been analyzed using the Wilson-Devinney (W-D) code and JHKS filter definitions computed for the W-D code in this work. Our analysis shows that the mass and radius of the primary and secondary components are 1.31 M ☉, 0.52 M ☉, 1.87 R ☉, and 0.48 R ☉, respectively. All results are compared with previously published literature values and discussed.

Optical monitoring of inter satellite distance between Turksat-2A And Turksat-3A

Geostationary satellites are objects, which revolve around the Earth where orbits are nearly circular and located on the equator plane with a period exactly equal to the rotation of the Earth. Most of such satellites are used for civil and military communication, television broadcasting and weather forecasting. Gravitational forces of the Sun, Moon and non-uniform mass distribution of the Earth perturb the geostationary orbits. Including these gravitational anomalies pressure of Solar winds is another source of perturbation. Because of these perturbations, orbits of geostationary satellites disturbed and some correction maneuvers must be performed.

Preparation of Spectra for Surface Mapping with Doppler Imaging of a Peculiar Star V776 Her

Our Sun is the only star that we can see thoroughly the surface of it. Chemically peculiar stars show anomalous abundances of some elements such as silicium, chromium and strontium. Doppler imaging is a useful technique for reconstructing the several structures on the surfaces of peculiar stars. We analyze our spectral observations as a preparation to Doppler imaging and compare V776 Hers observational spectra with the synthetic spectra that we produce with using the SPECTRUM code. The differences between the observational spectra and the synthetic spectra is discussed in this work.

Light curves and period changes of OO Aquilae

All available light curves and times of minima of OO Aql from the literature have been used to study the light curve and period variation of the system. Both the light curve and photometric period were found variable, but no simple correlation in between could be revealed. The present (O-C) data covering ~45000 cycles of orbital period is equaly well represended by two sloping straight lines or a large amplitude (A=0.0455 d) sinusoidal wave (with P=89 y). The sinusoidal variation, if real, predicts an unseen third star with a minimum mass of 0.8 M_sun; in the system. The systematic deviations of the data from the best representations have an amplitude of about 1x10^-6 d which may be caused by fluctuations in the mass transfer (or loss) rate, or magnetic activity variations of the component stars.