A Gamma Doradus Candidate In Eclipsing Binary BD And?

The BVR photometric light curves of the eclipsing binary BD And were obtained in 2008 and 2009. We estimated the mass ratio of the system as 0.97 and the photometric solutions were derived. The results show that BD And is a detached binary system, whose components have a little temperature difference of about 40 K. By analyzing photometric available light minimum times, we also derived an update ephemeris and found for the first time a possible periodic oscillation with an amplitude of 0.011 days and a period of 9.6 years. The results indicate that the periodic oscillation could be caused by a third component physically attached to the eclipsing binary. After removing the light variations due to the eclipses and proximity effects, the light-curve distortions are further explained by the pulsation of the primary component with a dominant period of 1 day. In accordance with the position of the primary component on the Hertzsprung-Russell diagram and its pulsation period, the primary component of BD And could be an excellent gamma Doradus candidate. It is rarely phenomenon that a component of the eclipsing binary system is a gamma Doradus variable.Comment: 34 pages, 8 figures. arXiv admin note: text overlap with arXiv:1112.1916 by other authors without attributio

Absolute Properties of An Overcontact Binary HH Boo

We obtained multi-colour light curves of HH Boo. We analysed the orbital period variation of the system. The analysis indicated that there is possible mass transfer from the second component to the primary or mass loss with -5.04x10-7 Msun per year. Re-analysing the available radial velocity curve, we analysed the light curves. The inclination (i) of the system was found to be 69.71(0.16) deg, while the semi-major axis (a) was computed as 2.246(0.064) Rsun. The mass of the primary component was found to be 0.92(0.08) Msun, while it was obtained as 0.58(0.06) Msun for the secondary component. The radius of the primary component was computed as 0.98(0.03) Rsun, while it was computed as 0.80(0.02) Rsun for the secondary component. We demonstrated that HH Boo should be a member of the A-type subclass of W UMa binaries.Comment: 20 pages, 5 figures, 4 table

V745\,Cassiopeia: an interacting young massive binary in a multiple star system

We present spectroscopic observations of the massive early type system V745\,Cas, embedded in a multiple star system. The brightest star of the system is the eclipsing binary V745\,Cas with an orbital period of 1.41 days. The radial velocities of both components and light curves obtained by $INTEGRAL$ and $Hipparcos$ missions were analysed. The components of V745\,Cas are shown to be a B0\,V primary with a mass M$_p$=18.31$\pm$0.51 M$_{\odot}$ and radius R$_p$=6.94$\pm$0.07 R$_{\odot}$ and a B(1-2)\,V secondary with a mass M$_s$=10.47$\pm$0.28 M$_{\odot}$ and radius R$_s$=5.35$\pm$0.05 R$_{\odot}$. Our analysis shows that both components fill their corresponding $Roche$ lobes, indicating double contact configuration. Using the UBVJHK magnitudes and interstellar absorption we estimated the mean distance to the system as 1700$\pm$50\,pc. The locations of the component stars in the mass-luminosity, mass-radius, effective temperature-mass and surface gravity-mass are in agreement with those of the main-sequence massive stars. We also obtained $UBV$ photometry of the three visual companions and we estimate that all are B-type stars based upon their de-reddened colours.We suspect that this multiple system is probably a member of the Cas OB4 association in the $Perseus$ arm of the $Galaxy$.Comment: 21 pages, 7 figures Accepted by MNRA

Long-term photometric and spectroscopic observations of the near-contact binary KR Cygni

We present the multi-color, five-year light curves and the first radial velocities of the near-contact binary system KR Cyg. We derived the masses of the components as 2.88$\pm$0.20 M$_{\odot}$ and 1.26$\pm$0.07 M$_{\odot}$ and the radii as 2.59$\pm$0.06 R$_{\odot}$ and 1.80$\pm$0.04 R$_{\odot}$. Analyses of the UBVR light curves and the radial velocities indicate that none of the components exactly fill their corresponding Roche lobes. We have calculated the distance to the system of KR Cyg as {411$\pm$12} pc using the observed apparent UBV magnitudes and the bolometric corrections for the component stars. We also searched for the empirical determination of albedo and effective temperature of the cooler, less massive star of KR Cyg, and of two similar near contact binaries AK CMi, and DO Cas. The residuals between the observed and computed fluxes are attributed to the effect of mutual illumination which heats the surface layers of the illuminated star and does vary not only its bolometric albedo but also its limb-darkening coefficient and gravity-brightening exponent. The analysis of the light curves shows that the effective albedos are generally smaller than that expected from an envelope of convective star, being mostly departed from the theoretical value at the B passband. As the reflected light diminishes the effective temperature and, therefore, the luminosity of the irradiated star increase. The observed bluer U-B colors during primary minimum are attributed to the effects of mutual irradiation and multiple scattering processes which may alter several characteristics of these systems.Comment: Accepted. 18 pages, 7 figures; 2012, October, Rev. Me