Marginally low mass ratio close binary system V1191 Cyg

In this study, we present photometric and spectroscopic variations of the extremely small mass ratio (q similar or equal to 0.1) late-type contact binary system V1191 Cyg. The parameters for the hot and cooler companions have been determined as M-h = 0.13 (1) M-circle dot, M-c = 1.29 (8) M-circle dot, R-h = 0.52 (15) R-circle dot, R-c = 1.31 (18) R, L-h = 0.46 (25) L-circle dot, L-c = 2.71 (80) L-circle dot, the separation of the components is a = 2.20 (8) R-circle dot and the distance of the system is estimated as 278 (31) pc. Analyses of the times of minima indicates a period increase of dp/dt = 1.3(1) x 10(-6) days/yr that reveals a very high mass transfer rate of dM/dt = 2.0(4) x 10(-7) M-circle dot/yr from the less massive component to the more massive one. New observations show that the depths of the minima of the light curve have been interchanged. (C) 2011 Elsevier B.V. All rights reserved.