Marginally low mass ratio close binary system V1191 Cyg

TL;DR

This paper studies the photometric and spectroscopic properties of the low mass ratio contact binary V1191 Cyg, revealing high mass transfer rates and changes in light curve minima depths, contributing new detailed parameters of this system.

Contribution

The study provides the first detailed parameters and analysis of V1191 Cyg, highlighting its extremely low mass ratio and high mass transfer rate, with observed changes in light curve minima.

Findings

High mass transfer rate of 2.0×10^{-7} M_sun/yr.

Period increase of 1.3×10^{-6} days/yr.

Interchanged minima depths in light curves.

Abstract

In this study, we present photometric and spectroscopic variations of the extremely small mass ratio ($q\simeq 0.1$) late-type contact binary system \astrobj{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.