* Astronomy

Title: V1135 Herculis: a double-lined eclipsing binary with an Anomalous Cepheid
Authors: E. Sipahi, C. Ibanoglu, O. Cakirli, H.A. Dal, S. Evren

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 ±0.00026 days. The orbital period of the system is about 39.99782 ±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 ±0.054 solar masses ~and M_2=0.504 ±0.040 solar masses and radii of R_1=27.1 ±0.4 solar radii and R_2=10.4 ±0.2 solar radii. 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 ±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 colour-magnitude and period-luminosity diagrams lead to a classification of an Anomalous Cepheid.

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