- ID:
- ivo://CDS.VizieR/J/AJ/144/50
- Title:
- Light curves of AV Hya and DZ Cas
- Short Name:
- J/AJ/144/50
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present BVR photometric observations and several eclipsing times for AV Hya and DZ Cas from 2004 to 2011. Using the Wilson-Devinney method, the photometric solutions with hot spots were deduced from their asymmetric light curves. The results indicate that both stars are Algol-type binaries, whose mass ratio, q_ph_, and fill-out factor of the primary, f_1_, are q_ph_=0.255(+/-0.002) and f_1_=81.2(+/-0.2)% for AV Hya, and q_ph_=0.093(+/-0.003) and f_1_=98.7(+/-0.3)% for DZ Cas. Based on all available light minimum times, it is discovered that the O-C curve of each star could be described by a light-time orbit overlying on a downward parabola. Their periods and amplitudes are P_3_=37.2(+/-0.7)yr and A=0.0095'(+/-0.0006') for AV Hya, and P_3_=62.5(+/-1.0)yr and A=0.0183'(+/-0.0007') for DZ Cas. Cyclic variations may result from the light-time effect due to the third body. The secular period decrease rates are dP/dt=-1.47(+/-0.04)x10^-7^days/yr for AV Hya and dP/dt=-0.92(+/-0.04)x10^-7^days/yr for DZ Cas. This may be interpreted using mass and angular momentum loss from the system. With decreasing period, the fill-out factor of the primary increases and it may finally fill its inner Roche lobe. Therefore, AV Hya and DZ Cas with a secular period decrease will evolve from semi-detached configurations into contact ones.
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- ID:
- ivo://CDS.VizieR/J/A+A/511/A3
- Title:
- Light curves of CoRoT-2 in z-band, 4.5um and 8um
- Short Name:
- J/A+A/511/A3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report measurements of the thermal emission of the young and massive planet CoRoT-2b at 4.5 and 8um with the Spitzer Infrared Array Camera (IRAC). Our measured occultation depths are 0.510+/-0.042% at 4.5 and 0.41+/-0.11% at 8um. In addition to the CoRoT optical measurements, these planet/star flux ratios indicate a poor heat distribution on the night side of the planet and agree better with an atmosphere free of temperature inversion layer. Still, such an inversion is not definitely ruled out by the observations and a larger wavelength coverage is required to remove the current ambiguity. Our global analysis of CoRoT, Spitzer, and ground-based data confirms the high mass and large size of the planet with slightly revised values (M_p_=3.47+/-0.22M_J_, R_p_=1.466+/-0.044 R_J_). We find a small but significant offset in the timing of the occultation when compared to a purely circular orbital solution, leading to e*cos(omega)=-0.00291+/-0.00063 where e is the orbital eccentricity and omega is the argument of periastron. Constraining the age of the system to at most a few hundred Myr and assuming that the non-zero orbital eccentricity does not come from a third undetected body, we modeled the coupled orbital-tidal evolution of the system with various tidal Q values, core sizes, and initial orbital parameters. For Q_s'_=10^5^-10^6^, our modeling is able to explain the large radius of CoRoT-2b if Q_p'_<=10^5.5^ through a transient tidal circularization and corresponding planet tidal heating event. Under this model, the planet will reach its Roche limit within 20Myr at most.
- ID:
- ivo://CDS.VizieR/J/AJ/148/126
- Title:
- Light curves of four overcontact binaries
- Short Name:
- J/AJ/148/126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze new, high quality multicolor light curves of four overcontact binaries: AK Her, HI Dra, V1128 Tau, and V2612 Oph, and determine their orbital and physical parameters using the modeling program of G. Djurasevic and recently published results of radial velocity studies. The achieved precision in absolute masses is between 10% and 20%, and the precision in absolute radii is between 5% and 10%. All four systems are W UMa-type binaries with bright or dark spots indicative of mass and energy transfer or surface activity. We estimate the distances and the ages of the systems using the luminosities computed through our analysis, and perform an O-C study for V1128 Tau, which reveals a complex period variation that can be interpreted in terms of mass loss/exchange and either the presence of the third body, or the magnetic activity on one of the components. We conclude that further observations of these systems are needed to deepen our understanding of their nature and variability.
- ID:
- ivo://CDS.VizieR/J/AJ/145/60
- Title:
- Light curves of GN Boo, BL Leo, and V1918 Cyg
- Short Name:
- J/AJ/145/60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new photometry for three short-period contact binaries, GN Boo, BL Leo, and V1918 Cyg, observed from 2008 December to 2012 April using several small telescopes in China. Photometric models were deduced from new observations using the updated Wilson-Devinney Code. The results show that GN Boo and BL Leo are W-type contact binaries, while V1918 Cyg is an A-type one. The mass ratios and fill-out factors are q=0.320(+/-0.002) and f=5.8(+/-0.1)% for GN Boo, q=0.476(+/-0.005) and f=21.3(+/-1.1)% for BL Leo, q=0.264(+/-0.002), and f=49.7(+/-0.7)% for V1918 Cyg, respectively. From the (O-C) curves, it is discovered that the orbital periods of three binaries have varied in a complicated way, i.e., cyclic oscillation for GN Boo, long-term period decrease for BL Leo, and both for V1918 Cyg. The cyclic variations for GN Boo and V1918 Cyg may probably be attributed to the magnetic activity of the primary component or light-time effect due to the third body. Meanwhile, the secular period decreases for BL Leo and V1918 Cyg may result from mass transfer from the primary to the secondary, accompanying the mass and angular momentum loss from the central system. Finally, GN Boo, BL Leo, and V1918 Cyg will evolve into deep contact binaries. Additionally, a statistical study of 37 contact binaries with decreasing periods is given. We obtained the relations of q-f and q-dlnP/dt, and preliminarily determined the mass loss rate of dln M/dt from the binary system.
- ID:
- ivo://CDS.VizieR/J/AJ/132/2489
- Title:
- Light curves of HD 71636 in B and V
- Short Name:
- J/AJ/132/2489
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Our differential BV photometric observations, acquired with an automated telescope at Fairborn Observatory, show that HD 71636 is an eclipsing binary. From follow-up red-wavelength spectroscopic observations we classify the primary and secondary as an F2 dwarf and an F5 dwarf, respectively. The system has a period of 5.01329 days and a circular orbit. We used the Wilson-Devinney program to simultaneously solve our BV light curves and radial velocities and determined a number of fundamental properties of the system. Comparison with evolutionary tracks indicates that both stars are well ensconced on the main sequence. The age of the system is about 1.2 billion years.
- ID:
- ivo://CDS.VizieR/J/AJ/145/80
- Title:
- Light curves of HS Aqr, EG Cep, VW LMi, DU Boo
- Short Name:
- J/AJ/145/80
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze new multicolor light curves for four close late-type binaries: HS Aqr, EG Cep, VW LMi, and DU Boo, in order to determine the orbital and physical parameters of the systems and estimate the distances. The analysis is done using the modeling code of G. Djurasevic, and is based on up-to-date measurements of spectroscopic elements. All four systems have complex, asymmetric light curves that we model by including bright or dark spots on one or both components. Our findings indicate that HS Aqr and EG Cep are in semi-detached, while VW LMi and DU Boo are in overcontact configurations.
- ID:
- ivo://CDS.VizieR/J/ApJ/745/58
- Title:
- Light curves of the PMS eclipsing binary Par 1802
- Short Name:
- J/ApJ/745/58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Parenago 1802, a member of the ~1 Myr Orion Nebula Cluster, is a double-lined, detached eclipsing binary in a 4.674 day orbit, with equal-mass components (M_2_/M_1_=0.985+/-0.029). Here we present extensive VI_C_JHK_S_light curves (LCs) spanning ~15 yr, as well as a Keck/High Resolution Echelle Spectrometer (HIRES) optical spectrum. The LCs evince a third light source that is variable with a period of 0.73 days, and is also manifested in the high-resolution spectrum, strongly indicating the presence of a third star in the system, probably a rapidly rotating Classical T Tauri star. We incorporate this third light into our radial velocity and LC modeling of the eclipsing pair, measuring accurate masses (M_1_=0.391+/-0.032 and M_2_=0.385+/-0.032M_{sun}_), radii (R_1_=1.73+/-0.02 and R_2_=1.62+/-0.02R_{sun}_), and temperature ratio (T_eff,1_/T_eff,2_=1.0924+/-0.0017). Thus, the radii of the eclipsing stars differ by 6.9%+/-0.8%, the temperatures differ by 9.2%+/-0.2%, and consequently the luminosities differ by 62%+/-3%, despite having masses equal to within 3%. This could be indicative of an age difference of ~3x10^5^yr between the two eclipsing stars, perhaps a vestige of the binary formation history. We find that the eclipsing pair is in an orbit that has not yet fully circularized, e=0.0166+/-0.003. In addition, we measure the rotation rate of the eclipsing stars to be 4.629+/-0.006 days; they rotate slightly faster than their 4.674 day orbit. The non-zero eccentricity and super-synchronous rotation suggest that the eclipsing pair should be tidally interacting, so we calculate the tidal history of the system according to different tidal evolution theories. We find that tidal heating effects can explain the observed luminosity difference of the eclipsing pair, providing an alternative to the previously suggested age difference.
- ID:
- ivo://CDS.VizieR/J/A+AS/130/245
- Title:
- Light curves of the PMS system TY CrA
- Short Name:
- J/A+AS/130/245
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Complete uvby light curves of the detached Herbig Be eclipsing binary TY Coronae Australis are presented. A total of 1787 photometric measurements in each of the four colours were obtained in 1989 and in 1992-1994. A detailed analysis of the y light curve obtained in 1992-1993 is published separately (Casey et al. 1997). The reflection nebula around the system contributes about 30% of the light in all four passbands. Here we present and discuss the non-eclipse-related photometric variability of the system. We suggest that these variations are the result of variable obscuration, possibly linked to dust shells physically associated to the system.
- ID:
- ivo://CDS.VizieR/J/A+AS/125/471
- Title:
- Light curves of the triple system V906 Sco
- Short Name:
- J/A+AS/125/471
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Complete uvby light curves of the detached triple-lined late B-type eclipsing binary V906 Scorpii, obtained from 1987 to 1991, are presented. A detailed photometric analysis based on these observations and on new spectroscopic material yields accurate masses and radii (errors <2%) for the components, confirms that the system is member of NGC 6475 (Messier 7) and is published separately (Alencar et al., 1997A&A...326..709A)
- ID:
- ivo://CDS.VizieR/J/AJ/133/1447
- Title:
- Light curves of variable stars in {omega} Cen
- Short Name:
- J/AJ/133/1447
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a variable star catalog of an extensive ground-based wide-field variability survey in the globular cluster omega Centauri. Using the Australian National University 40 inch (1m) telescope at Siding Spring Observatory, the cluster was observed with a 52'x52' (0.75deg^2^) field for 25 nights, from 2003 May 2 to May 27. A total of 187 variable stars were identified in the field, 81 of which are new discoveries. This work comprises the widest field variability survey yet undertaken for this cluster. Here we present the V+R light curves and preliminary analysis of the detected variable stars, comprising 58 eclipsing binaries, 69 RR Lyrae stars, 36 long-period variables (P>=2days), and 24 miscellaneous pulsators including 15 SX Phoenicis stars and two type II Cepheids.
