In this study , we present photometric and spectroscopic variations of the extremely small mass ratio ( q \simeq 0.1 ) late-type contact binary system V1191 Cyg .
The parameters for the hot and cooler companions have been determined as M _ { \textrm { h } } = 0.13 ( 1 ) M _ { \odot } , M _ { \textrm { c } } = 1.29 ( 8 ) M _ { \odot } , R _ { \textrm { h } } = 0.52 ( 15 ) R _ { \odot } , R _ { \textrm { c } } = 1.31 ( 18 ) R _ { \odot } , L _ { \textrm { h } } = 0.46 ( 25 ) L _ { \odot } , L _ { \textrm { c } } = 2.71 ( 80 ) L _ { \odot } , the separation of the components is a = 2.20 ( 8 ) R _ { \odot } and the distance of the system is estimated as 278 ( 31 ) pc .
Analyses of the times of minima indicates a period increase of \frac { dP } { dt } = 1.3 ( 1 ) \times 10 ^ { -6 } days/yr that reveals a very high mass transfer rate of \frac { dM } { dt } = 2.0 ( 4 ) \times 10 ^ { -7 } M _ { \odot } /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 .