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We present results of new photometric observations of the contact binary system astrobj{HI Pup} as well as the radial velocity curve of the system. Time series multicolour photometry was obtained at the South African Astronomical Observatory (SAAO) using the 1-m Cassegrain Telescope. We applied a simultaneous solution to the $BVRI$ light and radial velocity curves in order to determine the physical parameters of the system. From an analysis of the new multicolour data, the physical parameters were found to be $M_1=1.22M_{odot}$, $M_2=0.23M_{odot}$, $R_1=1.44R_{odot}$, $R_2=0.67R_{odot}$, $L_1=3.3L_{odot}$, $L_2=0.7L_{odot}$. Our solution confirms that HI Pup has a typical A--type W UMa binary system characteristics.
We present the results of the study of the contact binary system BO CVn. We have obtained physical parameters of the components based on combined analysis of new, multi-color light curves and spectroscopic mass ratio. This is the first time the latte
A growing number of eclipsing binary systems of the HW Vir kind (i. e., composed by a subdwarf-B/O primary star and an M dwarf secondary) show variations in their orbital period, also called Eclipse Time Variations (ETVs). Their physical origin is no
We carried out high-precision photometric observations of three eclipsing ultrashortperiod contact binaries (USPCBs). Theoretical models were fitted to the light-curves by means of the Wilson-Devinney code. The solutions suggest that the three target
Two CCD epochs of light minimum and a complete R light curve of SS Ari are presented. The light curve obtained in 2007 was analyzed with the 2003 version of the W-D code. It is shown that SS Ari is a shallow contact binary system with a mass ratio $q
A photometric UBV survey is presented for 610 stars in a region surrounding the Cepheid AQ Puppis and centered southwest of the variable, based upon photoelectric measures for 14 stars and calibrated iris photometry of photographic plates of the fiel