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

V1135 Herculis: a double-lined eclipsing binary with an Anomalous Cepheid

BVR light curves and radial velocities for the double-lined eclipsing binary V1135\,Her were obtained. The brighter component of V1135\,Her is a Cepheid variable with a pulsation period of 4.22433$\pm$0.00026 days. The orbital period of the system is about 39.99782$\pm$0.00233 days, which is the shortest value among the known Type\,II Cepheid binaries. The observed B, V, and R magnitudes were cleaned for the intrinsic variations of the primary star. The remaining light curves, consisting of eclipses and proximity effects, are obtained. Our analyses of the multi-colour light curves and radial velocities led to the determination of fundamental stellar properties of both components of the interesting system V1135\,Her. The system consists of two evolved stars, G1+K3 between giants and supergiants, with masses of M$_1$=1.461$\pm$0.054 \Msun ~and M$_2$=0.504$\pm$0.040 {\Msun} and radii of R$_1$=27.1$\pm$0.4 {\Rsun} and R$_2$=10.4$\pm$0.2 {\Rsun}. The pulsating star is almost filling its corresponding Roche lobe which indicates the possibility of mass loss or transfer having taken place. We find an average distance of d=7500$\pm$450 pc using the BVR magnitudes and also the V-band extinction. Location in the Galaxy and the distance to the galactic plane with an amount of 1300 pc indicate that it probably belongs to the thick-disk population. Most of the observed and calculated parameters of the V1135\,Her and its location on the color-magnitude and period-luminosity diagrams lead to a classification of an Anomalous Cepheid.Comment: 25 pages, 9 Tables, 9 Figures, Accepted Revista Mexicana de Astronom\'ia y Astrof\'isica. arXiv admin note: substantial text overlap with arXiv:1211.120

Cinética de oxidación del aceite de avellana tratado con ozono

The present study investigates the oxidation kinetics of hazelnut oil ozonated in different treatment periods (1, 5, 60 and 180 min). The kinetic rate constant (k) was taken as the inverse of oxidation onset time (To) observing a linear relationship from the plot of lnTo to isothermal temperatures (373, 383, 393, and 403 K) carried out at differential scanning calorimetry. Kinetic parameters, activation energy (Ea), activation enthalpy (ΔH‡) and entropy (ΔS‡) were calculated based on the Arrhenius equation and activated complex theory. k values showed an exponential rise with the increase of ozone treatment time. The increase in k correlated well with the increase in the peroxide and free fatty acid values of all samples. Ea and ∆H‡ of the ozone treated oils showed a reducing trend and reflected an increased oxidation sensitivity after ozone treatment. Consistently, an increase in ∆S‡ indicated a faster oxidation reaction with an increase in ozone exposure time. However, no significant difference was observed in k, Ea, ΔH‡, ΔS‡ (p < 0.05) as a function of storage period, after the hazelnut oil was treated with ozone for 1 min.El presente estudio investiga la cinética de oxidación del aceite de avellana ozonizado durante diferentes períodos (1, 5, 60 y 180 min). La constante de velocidad cinética (k) se tomó como la inversa del tiempo de inicio de la oxidación (To) observando una relación lineal cuando se representa el lnTo con las temperaturas isotérmicas (373, 383, 393 y 403 K) llevadas a cabo en calorimetría de barrido diferencial. Los parámetros cinéticos, energía de activación (Ea), entalpía de activación (ΔH‡) y entropía (ΔS‡) se calcularon sobre la base de la ecuación de Arrhenius y de la teoría compleja activada. Los valores de k mostraron un aumento exponencial con el aumento del tiempo de tratamiento de ozono. El aumento de k se correlacionó bien con el aumento de peróxidos y de los ácidos grasos libres de todas las muestras. Ea y ΔH‡ de los aceites tratados con ozono mostraron una tendencia reductora que refleja una mayor sensibilidad a la oxidación de los aceites después del tratamiento con ozono. Consistentemente, un aumento de ΔS‡ indicó una reacción de oxidación más rápida con un aumento del tiempo de exposición al ozono. Sin embargo, no se observó diferencia significativa en k, Ea, ΔH‡, ΔS‡ (p < 0.05) en función del período de almacenamiento, después de que el aceite de avellana fue tratado con ozono durante 1 min