V1005 Her: a solar-type shallow-contact binary in a triply fossil system

2019 ◽  
Vol 489 (2) ◽  
pp. 2677-2684 ◽  
Author(s):  
L-Y Zhu ◽  
Z H Wang ◽  
X M Tian ◽  
L J Li ◽  
X Gao
Keyword(s):  
Magnetic Activity ◽  
Light Curves ◽  
Cyclic Variation ◽  
Third Body ◽  
Light Curve Analysis ◽  
Short Period ◽  
Contact Binary ◽  
Solar Type ◽  
Activity Cycles ◽  
Minimal Mass

ABSTRACTFour sets of complete multicolour light curves of the short-period solar-type eclipsing binary V1005 Her are presented. It is found that the depth of the primary minima in the light curves went deeper from 2013 to 2018, and then became shallower again in 2019, while those of the secondary minima were unchanged. The total-eclipse characteristics in the light curves enable us to determine reliable photometric solutions of this system. Our results from the detailed light-curve analysis show that V1005 Her is a W-type shallow-contact binary with spot activities. We have monitored this system for 7 yr and 22 new times of light minimum have been determined. Together with those collected from the literature, we investigate its Observed-Calculated O–C curve and detect a cyclic variation. Because of the insufficient energy, this cyclic change cannot be explained by magnetic activity cycles of the components even if it has high spots activities. The detected cyclic variation is more plausible as the results of the light-time effect due to the existence of a third body orbiting around the central binary. The minimal mass of the additional stellar companion is determined around 0.45 M⊙ in both circular orbit and eccentric orbit cases when a total mass of 1.2 M⊙ for the binary is adopted. This mass is larger than that of the less massive component of the central binary. It implies that the secondary body was not replaced by the third body during early stellar interactions, suggesting that it is a fossil system and keeps original dynamical information.

scholarly journals New Photometric Investigation of the Solar-Type Shallow-Contact Binary HH Bootis

2019 ◽  
Vol 2019 ◽  
pp. 1-18
Author(s):  
Jia-jia He ◽  
Jing-jing Wang
Keyword(s):  
Light Curves ◽  
Mass Ratio ◽  
Third Body ◽  
Light Minimum ◽  
Short Period ◽  
Cyclic Oscillation ◽  
Type Contact ◽  
Contact Binary ◽  
Solar Type ◽  
Photometric Investigation

The short-period solar-type contact binary HH Boo was monitored photometrically for about 8 years. It is found that the CCD light curves in the B, V, R, and I bands obtained in 2010 are symmetric, while the multicolor light curves observed in 2011 and 2012 by several investigators showed a positive O’Connell effect where the maxima following the primary minima are higher than the other ones. This indicates that the light curve of the solar-type contact binary is variable. By analyzing our multicolor light curves with the Wilson-Devinney code (W-D code), it is confirmed that HH Boo is a W-type shallow-contact binary system with a mass ratio of q = 1.703(31) and a degree of contact factor of f = 12.86%(0.73%). By including 109 new determined times of light minimum together with those compiled from the literature, it is detected that the O-C diagram shows a cyclic oscillation with a period of T3 = 6.58(11) yr and an amplitude of A3 = 0.0018(1) d. The cyclic change may reveal the presence of an extremely cool third body orbiting the central binary.

scholarly journals Light-time effect detected in fourteen eclipsing binaries

2020 ◽  
Vol 643 ◽  
pp. A130
Author(s):  
P. Zasche ◽  
R. Uhlař ◽  
P. Svoboda ◽  
P. Cagaš ◽  
M. Mašek
Keyword(s):  
Time Effect ◽  
Eclipsing Binaries ◽  
Light Curves ◽  
Physical Parameters ◽  
Third Body ◽  
Light Curve Analysis ◽  
Multiple Systems ◽  
The Third ◽  
Minimal Mass ◽  
Triple Star

The available minima timings of 14 selected eclipsing binaries (V1297 Cas, HD 24105, KU Aur, GU CMa, GH Mon, AZ Vel, DI Lyn, DK Her, GQ Dra, V624 Her, V1134 Her, KIC 6187893, V1928 Aql, V2486 Cyg) were collected and analyzed. Using the automatic telescopes, surveys, and satellite data, we derived more than 2500 times of eclipses, accompanied with our own ground-based observations. These data were used to detect the period variations in these multiple systems. The eclipse timing variations were described using the third-body hypothesis and the light-time effect. Their respective periods were derived as 2.5, 16.2, 27, 20, 64, 5.6, 22, 115, 27, 42, 6.9, 11.2, 4.1, and 8.4 years for these systems, respectively. The predicted minimal mass of the third body was calculated for each of the systems, and we discuss here their prospective detectability. The light curves of HD 24105, GH Mon, DK Her, V1134 Her, KIC 6187893, V1928 Aql, and V2486 Cyg were analyzed using the PHOEBE program, resulting in physical parameters of the components. Significant fractions of the third light were detected during the light-curve analysis, supporting our hypothesis of the triple-star nature of all these systems. The majority of these systems (nine out of 14) were already known as visual doubles. Our study shifts them to possible quadruples, what makes them even more interesting.

scholarly journals Comparison of the power-2 limb-darkening law from the STAGGER-grid to Kepler light curves of transiting exoplanets

2018 ◽  
Vol 616 ◽  
pp. A39 ◽  
Author(s):  
P. F. L. Maxted
Keyword(s):  
Light Curve ◽  
Probability Distributions ◽  
Binary Star ◽  
Magnetic Activity ◽  
Light Curves ◽  
Practical Implementation ◽  
Light Curve Analysis ◽  
Stagger Grid ◽  
Least Squares Fit ◽  
Limb Darkening

Context. Inaccurate limb-darkening models can be a significant source of error in the analysis of the light curves for transiting exoplanet and eclipsing binary star systems, particularly for high-precision light curves at optical wavelengths. The power-2 limb-darkening law, Iλ(µ) = 1 − c(1−µα), has recently been proposed as a good compromise between complexity and precision in the treatment of limb-darkening. Aims. My aim is to develop a practical implementation of the power-2 limb-darkening law and to quantify the accuracy of this implementation. Methods. I have used synthetic spectra based on the 3D stellar atmosphere models from the STAGGER-grid to compute the limb-darkening for several passbands (UBVRI, CHEOPS, TESS, Kepler, etc.). The parameters of the power-2 limb-darkening laws are optimized using a least-squares fit to a simulated light curve computed directly from the tabulated Iλ(μ) values. I use the transformed parameters h1 = 1 − c(1 − 2−α) and h2 = c2−α to directly compare these optimized limb-darkening parameters to the limb darkening measured from Kepler light curves of 16 transiting exoplanet systems. Results. The posterior probability distributions (PPDs) of the transformed parameters h1 and h2 resulting from the light curve analysis are found to be much less strongly correlated than the PPDs for c and α. The agreement between the computed and observed values of (h1, h2) is generally very good but there are significant differences between the observed and computed values for Kepler-17, the only star in the sample that shows significant variability between the eclipses due to magnetic activity (star spots). Conclusions. The tabulation of h1 and h2 provided here can be used to accurately model the light curves of transiting exoplanets. I also provide estimates of the priors that should be applied to transformed parameters h1 and h2 based on my analysis of the Kepler light curves of 16 stars with transiting exoplanets.

scholarly journals Variability of the Light Curves of the Close Binary GR Tauri

2002 ◽  
Vol 187 ◽  
pp. 337-338
Author(s):  
A. Yamasaki ◽  
M. Takeda ◽  
T. Yamauchi ◽  
G. Takada ◽  
S. Hattori
Keyword(s):  
Binary System ◽  
The State ◽  
Light Curves ◽  
Close Binary ◽  
Eclipsing Binary ◽  
Short Period ◽  
Contact Binary

AbstractVariability of the light curves of the short-period eclipsing binary system GR Tau (, almost-contact binary) is studied. It is found that GR Tau experienced both the state which is characterized by asymmetric light curves and the state characterized by symmetrical light curves.

A high-mass-ratio red-dwarf contact binary with an extremely cool close-in red dwarf

2019 ◽  
Author(s):  
Xiao-Hui Fang ◽  
Shengbang Qian ◽  
Miloslav Zejda ◽  
Soonthornthum Boonrucksar ◽  
Xiao Zhou ◽  
...  
Keyword(s):  
Orbital Period ◽  
Light Curves ◽  
High Mass ◽  
Mass Ratio ◽  
Third Body ◽  
Dynamical Interaction ◽  
The Third ◽  
Short Period ◽  
Contact Binaries ◽  
Mass Component

Abstract 1SWASP J161335.80$-$284722.2 (hereafter J161335) is an eclipsing red-dwarf binary with an orbital period of $0.229778\:$d, which is around the short-period limit for contact binaries. Three sets of multi-color light curves of J161335 were obtained from different telescopes in 2015 and 2016 and are analyzed using the Wilson–Devinney method. We discovered that the system is a W-type contact system with a contact degree of 19% and a high mass ratio of 0.91. By using all available eclipse times, we found that the observed $-$ calculated $(O-C)$ diagram displays a cyclic oscillation with an amplitude of 0.00196($\pm 0.00006)\:$d and a period of 4.79($\pm 0.14)\:$yr while it undergoes a downward parabolic change. This downward variation corresponds to a continuous decrease in the orbital period at a rate of $dP/dt = -4.26(\pm$0.01) $\times$ 10$^{-7}\:$d$\:$yr$^{-1}$. The small-amplitude oscillation is explained as the light travel-time effect from the gravitational influence of a third body with a lowest mass of $M _{3}$ = 0.15($\pm 0.01)M_{\,\odot }$. In solving the light curves, we found that the third light is increasing, with the wavelength suggesting that the third body may be a cool red dwarf. This is in agreement with the results obtained by analyzing the $O-C$ diagram. The tertiary red dwarf is orbiting the central red-dwarf binary at an orbital separation of 2.8($\pm 0.2$) au. These results suggest that the J161335 system may be formed through early dynamical interaction where the original low-mass component was replaced by a higher-mass third body and the lower-mass component was kicked out to a wider orbit. In this way, a hierarchical triple system similar to J161335 with a high-mass-ratio binary and a small close-in third body is formed.

scholarly journals Magnetic Activity of Two Similar Subgiants in Binaries with Very Different Mass Ratios: EI Eri and V711 Tau

2011 ◽  
Vol 7 (S282) ◽  
pp. 478-479 ◽  
Author(s):  
Katalin Oláh ◽  
Zsolt Kővári ◽  
Krisztián Vida ◽  
Klaus G. Strassmeier
Keyword(s):  
Differential Rotation ◽  
Activity Patterns ◽  
Magnetic Activity ◽  
Light Curves ◽  
Physical Parameters ◽  
Remarkable Difference ◽  
High Latitudes ◽  
Solar Type ◽  
Low Mass ◽  
Fast Rotating

AbstractWe use more than three decades-long photometry to study the activity patterns on the two fast-rotating subgiant components in EI Eri (G5IV) and V711 Tau (K1IV). From yearly mean rotational periods from the light curves, we find that EI Eri, with well-measured solar-type differential rotation, always has spots from the equator to high latitudes. The measured differential rotation of V711 Tau is controversial, and in any case is very small. The spots on the K1IV star in V711 Tau seem to be tidally locked. The physical parameters of the two systems are similar, with one remarkable difference: EI Eri has a low mass M4-5 dwarf companion, whereas V711 Tau has a G5V star in the system, thus their mass centers are in very different positions. This may modify the whole internal structure of the active stars, causing marked differences in their surface features.

scholarly journals UBVRI Photometric Analysis of the Solar-Type Eclipsing Binary TYC 3034-299-1

2012 ◽  
Vol 2012 ◽  
pp. 1-11
Author(s):  
Ronald G. Samec ◽  
Adam Jaso ◽  
Jesse White ◽  
Danny R. Faulkner ◽  
Nicholas Blum ◽  
...  
Keyword(s):  
Light Curve ◽  
Massive Star ◽  
Light Curves ◽  
Dark Spot ◽  
Mass Ratio ◽  
Photometric Analysis ◽  
Contact Binary ◽  
Solar Type ◽  
Curve Solution ◽  
Light Curve Solution

TYC 3034-0299-1 (CVn) is a magnetically active, contact binary, ROTSE variable. UBVRcIc light curves are presented along with a period study and a simultaneous UBVRI light curve solution. Our light curves show eclipse amplitudes of 0.72 and 0.62 mags (V) in the primary and secondary eclipses. Modeled results include a dark spot region, found at longitude 51°, a 24% Roche lobe fill-out, and a mass ratio of 0.48. A total eclipse is found to occur in the secondary eclipse making TYC 3034-0299-1 a W-type (less massive star is hotter) W UMa variable.

Solar Rotation, Irradiance Changes and Climate

1994 ◽  
Vol 143 ◽  
pp. 244-251
Author(s):  
Elizabeth Nesme-Ribes ◽  
Dmitry Sokoloff ◽  
Robert Sadourny
Keyword(s):  
Magnetic Fields ◽  
Internal Rotation ◽  
Solar Rotation ◽  
Total Solar Irradiance ◽  
Magnetic Activity ◽  
Convective Envelope ◽  
Surface Rotation ◽  
Solar Type ◽  
Activity Cycles ◽  
The Impact

Magnetic activity cycles for solar-type stars are believed to originate from non-uniform internal rotation. To determine this depthwise angular velocity distribution, helioseismology is a valuable source of information. Surface rotation, as traced by sunspot motion, is a well-observed parameter with data going back to the beginning of the telescopic era. This long sunspot series can be used in understanding the behaviour of the Sun’s surface rotation, the connection with its internal rotation, and thereby its magnetic activity. Apparent solar diameter is another important parameter. This is related to the structure of the convective envelope and how it reacts to the presence of magnetic fields. Both these parameters are related to the solar output, and can provide a surrogate for total solar irradiance, by way of a theoretical modeling of the response of the convective zone to the emergence of periodic magnetic fields. The impact of solar variability on the terrestrial climate is also addressed.

scholarly journals Synthetic Light Curve Analysis of the Close Binary Systems BX Andromedae and RR Leporis

1989 ◽  
Vol 107 ◽  
pp. 359-360
Author(s):  
R.G. Samec ◽  
R.E. Fuller ◽  
R. H. Kaitchuck ◽  
B. B. Bookmyer ◽  
D. R. Faulkner
Keyword(s):  
Light Curve ◽  
Binary Systems ◽  
Thermal Relaxation ◽  
Curve Analysis ◽  
Light Curves ◽  
Close Binary ◽  
Comparison Star ◽  
Short Time Scale ◽  
Light Curve Analysis ◽  
Short Period

AbstractUnpublished photoelectric observations of the systems BX And and RR Lep were subjected to light curve analysis using the Wilson-Devinney Code.The short-period eclipsing binary system BX And was observed on five nights in 1976 at the Morgan-Monroe station of the Goethe Link Observatory of Indiana University. The observations covering the eclipse portions of the light curves yielded four times of minimum light. A period study covering 89 years of observations confirms that a major period change took place about 1950. The system is suspected of being quite active on a short time scale. Standard magnitudes were derived for BX And and for the comparison star. The corrected color indices indicate that BX And and the comparison star BD+39° 476 are in the spectral range of F3-F5. The light curves, defined by 1092 observations in B, 1097 in V and 971 in the U filter are symmetric. The difference in the eclipse depths are quite large averaging 0.m46. A distinct de-reddening of the light curves occurs during the secondary eclipse. The first synthetic light curve solutions of the system were obtained. The solution of BX And indicates that the system consists of an F-type primary and a K-type secondary component in a state of shallow contact. This result is supported by the location of BX And on the Eggen period-color diagram for contact binaries. The large mass ratio, temperature disparity and period increase are found to be consistent with an early contact phase of thermal relaxation oscillations.

Investigation on the mass transferring near-contact binary TT Cet

2020 ◽  
Vol 37 ◽  
Author(s):  
Xiao-Man Tian ◽  
Lin-Feng Chang
Keyword(s):  
Mass Transfer ◽  
Light Curve ◽  
Hot Spot ◽  
Relaxation Oscillation ◽  
Thermal Relaxation ◽  
Light Curves ◽  
Primary Star ◽  
Contact Stage ◽  
Short Period ◽  
Contact Binary

Abstract First multi-colour complete light curves and low-resolution spectra of short-period eclipsing binary TT Cet are presented. The stellar atmospheric parameters of the primary star were derived through spectra fitting as: $T_{eff}=7\,091\pm124\,{\text{K}}$ , $\log g = 4.15\pm0.33\,{\text{cm}}/\text{s}^2$ , and $[Fe/H]=-0.23\pm0.04\,\text{dex}$ . The light curves were analysed using the Wilson–Devinney code. The photometric solution suggests that this target should be a near-contact binary with the primary component filling its critical Roche lobe (i.e. SD1-type NCB). The luminosity enhancement around the primary light maximum (phase 0.10–0.40) on the light curve was detected like other SD1-type NCBs, which could be caused by a hot spot near the facing surface of the secondary component due to mass transfer. Long-term decrease of the orbital period at a rate of $dP/dt=-5.01\,({\pm}0.06)\times 10^{-8}\,{{\text{d}} \cdot{yr}}^{-1}$ was detected by the O–C analysis, which supports the mass transfer from the primary to the secondary and is consistent with its primary filling configuration. No third body was found through the light curve and O–C analysis. TT Cet may locate in the broken contact stage predicted by the thermal relaxation oscillation theory (TRO) and will evolve to the contact stage eventually. It is another good observational example supporting the TRO theory. We have collected all known SD1-type NCBs with absolute parameters from the literatures. The relations of these parameters are summarised for these rare systems.

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