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Register a new userMarginally low mass ratio close binary system V1191 Cyg
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In this study, we present photometric and spectroscopic variations of the extremely small mass ratio ($qsimeq 0.1$) 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.
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In this study, we present long term photometric variations of the close binary system astrobj{GO Cyg}. Modelling of the system shows that the primary is filling Roche lobe and the secondary of the system is almost filling its Roche lobe. The physical parameters of the system are $M_1 = 3.0pm0.2 M_{odot}$, $M_2 = 1.3 pm 0.1 M_{odot}$, $R_1 = 2.50pm 0.12 R_{odot}$, $R_2 = 1.75 pm 0.09 R_{odot}$, $L_1 = 64pm 9 L_{odot}$, $L_2 = 4.9 pm 0.7 L_{odot}$, and $a = 5.5 pm 0.3 R_{odot}$. Our results show that astrobj{GO Cyg} is the most massive system near contact binary (NCB). Analysis of times of the minima shows a sinusoidal variation with a period of $92.3pm0.5$ years due to a third body whose mass is less than 2.3$M_{odot}$. Finally a period variation rate of $-1.4times10^{-9}$ d/yr has been determined using all available light curves.
In this study we determined precise orbital and physical parameters of the very short period low-mass contact binary system CC Com. The parameters are obtained by analysis of the new CCD data with the archival spectroscopic data. The physical parameters of the components derived as $M_textrm{c}$ = 0.717(14) $M_{odot}$, $M_textrm{h}$ = 0.378(8) $M_{odot}$, $R_textrm{c}$ = 0.708(12) $R_{odot}$, $R_textrm{h}$ = 0.530(10) $R_{odot}$, $L_textrm{c}$ = 0.138(12) $L_{odot}$, $L_textrm{h}$ = 0.085(7) $L_{odot}$, and the distance of the system is estimated as 64(4) pc. The times of minima obtained in this study and with those published before enable us to calculate the mass transfer rate between the components which is $1.6times10^{-8}$ M$_{odot}$yr$^{-1}$. Finally, we discuss the possible evolutionary scenario of CC Com.
The cut-off mass ratio is under debate for contact binaries. In this paper, we present the investigation of two contact binaries with mass ratios close to the low mass ratio limit. It is found that the mass ratios of VSX J082700.8+462850 (hereafter J082700) and 1SWASP J132829.37+555246.1 (hereafter J132829) are both less than 0.1 ($qsim0.055$ for J082700, and $qsim0.089$ for J132829). J082700 is a shallow contact binary with a contact degree of $sim$19%, and J132829 is a deep contact system with a fillout factor of $sim$70%. The $O-C$ diagram analysis indicated that both the two systems manifest long-term period decrease. In addition, J082700 exhibits a cyclic modulation which is more likely resulted from Applegate mechanism. In order to explore the properties of extremely low mass ratio contact binaries (ELMRCBs), we carried out a statistical analysis on contact binaries with mass ratios of $qlesssim0.1$ and discovered that the values of $J_{spin}/J_{orb}$ of three systems are greater than 1/3. Two possible explanations can interpret this phenomenon. One is that some physical processes, unknown to date, are not considered when Hut presented the dynamically instability criterion. The other is that the dimensionless gyration radius ($k$) should be smaller than the value we used ($k^2=0.06$). We also found that the formation of ELMRCBs possibly has two channels. The study of evolutionary states of ELMRCBs reveals that their evolutionary states are similar with those of normal W UMa contact binaries.
Two CCD epochs of light minimum and a complete R light curve of SS Ari are presented. The light curve obtained in 2007 was analyzed with the 2003 version of the W-D code. It is shown that SS Ari is a shallow contact binary system with a mass ratio $q=3.25$ and a degree of contact factor f=9.4(pm0.8%). A period investigation based on all available data shows that there may exist two distinct solutions about the assumed third body. One, assuming eccentric orbit of the third body and constant orbital period of the eclipsing pair results in a massive third body with $M_3=1.73M_{odot}$ and P_3=87.0$yr. On the contrary, assuming continuous period changes of the eclipsing pair the orbital period of tertiary is 37.75yr and its mass is about $0.278M_{odot}$. Both of the cases suggest the presence of an unseen third component in the system.
BD And is a fairly bright (V = 10.8), active and close (P = 0.9258 days) eclipsing binary. The cyclic variability of the apparent orbital period as well as third light in the light curves indicate the presence of an additional late-type component. The principal aim is the spectroscopic testing of the third-body hypothesis and determination of absolute stellar parameters for both components of the eclipsing binary. First medium and high-resolution spectroscopy of the system was obtained. The broadening-function technique appropriate for heavily-broadened spectra of close binaries was used. The radial velocities were determined fitting the Gaussian functions and rotational profiles to the broadening functions. A limited amount of photometric data has also been obtained. Although the photometric observations were focused on the obtaining the timing information, a cursory light-curve analysis was also performed. Extracted broadening functions clearly show the presence of a third, slowly-rotating component. Its radial velocity is within error of the systemic velocity of the eclipsing pair, strongly supporting the physical bond. The observed systemic radial-velocity and third-component changes do not support the 9 year orbit found from the timing variability. Masses of the components of the eclipsing pair are determined with about 0.5% precision. Further characterization of the system would require long-term photometric and spectroscopic monitoring.
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