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Abstract. New BV light curves and times of minimum light for the short period W UMa system LO And were analyzed to derive the preliminary physical parameters of the system. The light curves were obtained at Ankara University Observatory during 5 nights in 2003. A new ephemeris is determined for the times of primary minimum. The analysis of the light curves is made using the Wilson-Devinney 2003 code. The present solution reveals that LO And has a photometric mass ratio q = 0.371 and is an A-type contact binary. The period of the system is still increasing, which can be attributed to light-time effect and mass transfer between the components. With the assumption of coplanar orbit of the third body the revealed mass is M3 = 0.21M . If the period change dP/dt = 0.0212 sec/yr is caused only by the mass transfer between components (from the lighter component to the heavier) the calculated mass transfer rate is dm/dt = 1.682 × 10 −7 M /yr. The absolute radii and masses estimated for the components, based on our photometric solution and the absolute parameters of the systems which have nearly same period are R1 = 1.30R , R2 = 0.85R , M1 = 1.31M , M2 = 0.49M respectively for the primary and secondary components.

New BVR light curves and times of minimum light for the short period β Lyrae system V Tri were analyzed to derive the physical parameters of the system. The light curves were obtained at Ankara University Observatory and at the TÜBİTAK National Observatory during 5 nights in 2001 and 2002. A new ephemeris is determined for the times of primary minimum. The analysis of the light curves is made using the Wilson-Devinney 2003 code. The present solution reveals that V Tri is a near-contact system with a mass ratio near 0.5. The absolute radii and masses estimated for the components, based on our photometric solution, are R1 = 1.94 R , R2 = 1.44 R , M1 = 2.68 M , M2 = 1.36 M , respectively, for the primary and secondary components. The period variation of the system can be attributed to the light-time effect. With the assumption of a coplanar orbit of the third body its revealed mass is m 3 = 0.17 M .

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