New Times Of Minima Research Articles

Light curve analysis and evolutionary status of four newly identified short-period eclipsing binaries

We present the physical and orbital parameters of four short-period eclipsing W UMa systems: ZTFJ000030.44+391106.9\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ZTFJ000030.44 +391106.9$$\\end{document} (referred to as S1), ZTFJ000817.08+402532.1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ZTFJ000817.08+402532.1$$\\end{document} (referred to as S2), ZTFJ002158.44+252934.04\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ZTFJ002158.44+252934.04$$\\end{document} (referred to as S3), and ZTFJ003357.62+415747.8\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ZTFJ003357.62+415747.8$$\\end{document} (referred to as S4). The absolute parameters and evolutionary status of these systems are determined, and new times of minima are calculated. Additionally, we present the 3D fill-out configuration for each system. The four Systems exhibit moderate contact W UMa binary with a fill-out factor of 49%, 38%, 28%, and 51%, respectively. Comparing the systems’ periods, we observed a proportional relationship, where shorter periods correspond to lower fill-out factors, and longer periods were associated with higher fill-out factors. Based on the derived surface temperatures and mass ratios of the components, all systems are classified as A-type W UMa binaries. The obtained parameters in addition to a list of previously published data are then utilized to derive an updated Mass-Luminosity relation (M-L) for both A and W-type eclipsing W UMa systems. A comparison with previously published relations reveals that the majority of the EW systems lie between 0.2 and 2 Msun on the M-L diagram. Moreover, we discuss the dynamical evolutionary aspects and evolutionary status of the four components, along with their positions on the Zero Age Main Sequence (ZAMS) and Terminal Age Main Sequence (TAMS).

Optical and X-Ray Studies of Marginal Contact Binary RW Dor Using TESS and XMM-Newton Observatories

Marginal short-period contact binaries are important to understand as they pose a different physical scenario than the predicted theoretical model based on the thermal relaxation oscillation mechanism due to their shallow degree of contact. Here we present the optical and X-ray studies of a contact binary source RW Dor using the Transiting Exoplanet Survey Satellite (TESS) and XMM-Newton telescopes. For the first time we report the varying O’Connell effect and explain the asymmetry with a spot model. Based on the new times of minima, we make a robust estimate of the orbital period of the third body at 47.01 ∼ 0.52 yr with an eccentricity e = 0.21. We show that the period-decreasing trend observed in O − C variation can be explained by both conservative mass transfer from primary to secondary and AML via stellar wind. The X-ray luminosity exhibited by RW Dor did not vary significantly on three different occasions and was found to be about 3.34 × 1029 erg s−1. Assuming that the quiescent X-ray emission is emitted from an undisturbed loop structure, the loop size is estimated to be 0.6–1 × 1010 cm which is ≤Alfvén radius r A ∼ 8 × 1010 cm.

A holistic study of the systems V0487 Lac, V0566 Hya, and V0666 Lac

Abstract A comprehensive photometric study and evolutionary state for the systems V0487 Lac, V0566 Hya, and V0666 Lac were carried out by means of their first photometric observations. New times of minima were estimated from the observed light curves, and first (O–C) curves were established for all systems. The radiative treatment was carried out using a Windows interface version of the Wilson and Devinney programme (W–D). The adopted models provide some absolute characteristics for the systems under study, which are used to determine the spectral type of the system’s constituents and their evolutionary stage. Distances to each system were calculated, and physical properties were estimated. All system components, with the exception of the secondary component of the system V0487 Lac, showed good fit when the systems were positioned on the theoretical mass–luminosity and mass–radius relations.

First photometric analysis of the two EW binaries ZTF J214226.88+435827.1 and KAO-EGYPT J214216.38+440015.1

The EW-type eclipsing binaries are strongly interacting systems known to have often both component stars filling their crucial Roche lobes and having a common envelope. We present new BVRI light curves of the eclipsing binaries ZTF J214226.88+435,827.1 (ZTF21+43) and KAO-EGYPT J214216.38+440,015.1 (KAO21+44) based on CCD observations acquired with the 1.88-m Kottamia Astronomical Observatory (KAO) at Newtonian and Cassegrain telescope focus. The modeling results show that these two systems are to be W UMa contact binaries belonging to EW subtypes. All the light curves show the inverse O'Connell effect. We computed new ephemeris for each system using our times of minima and that available in the literature. Using our new times of minima and epochs for both systems from all available observations, the orbital period changes of these structures are studied for our systems. Using the PHOEBE package, a preliminary determination of the two systems' photometric orbital and physical parameters has been present. The positions of the systems were also depicted on the Hertzsprung-Russell (H-R), M-L, and Teff-L diagrams to test their evolutionary status.

Eclipse timing variations in the WD + dM eclipsing binary RR Cae

ABSTRACT We present the binary model and the eclipse timing variations of the eclipsing binary RR Cae, which consists of a white dwarf eclipsed by an M-type dwarf companion. The multiwavelength optical photometry from the Transiting Exoplanet Survey Satellite (TESS), the 0.6-m PROMPT-8 telescope, and the 0.7-m Thai Robotic Telescope at Spring Brook Observatory, combined with archive H α radial velocities from the Very Large Telescope (VLT) are analysed. From the data, the physical parameters of the system are obtained along with 430 new times of minima. The TESS light curves in 2018 and 2020 show out-of-eclipse variations, which might be caused by a large spot on the secondary component. The light travel time effect models due to the gravitational interaction of one or two circumbinary objects are adopted to fit the cyclic variations in the RR Cae’s O-C curve. The fitting solution of the O-C curve with one circumbinary object model shows a periodic variation with a period of 16.6 ± 0.2 yr and an amplitude of 14 ± 1 s, which can be caused by a planet with a minimum mass of 3.4 ± 0.2 MJup. When we consider the model with two circumbinary objects, the O-C curve shows cyclic variations with periods of 15.0 ± 0.5 yr and 39 ± 5 yr and amplitudes of 12 ± 1 s and 20 ± 5 s, respectively, corresponding to minimum masses of 3.0 ± 0.3 MJup and 2.7 ± 0.7 MJup.

44 Boo – A unified integrated light curve analysis

Radial velocity (RV) data from Lu et al. (2001) were combined with light curve (LC) data from the Transiting Exoplanet Survey Satellite (TESS) in an integrated Wilson-Devinney analysis to yield fundamental parameters. Obtained were masses M 1 = 0.526 (5), M ʘ, and M 2 = 1.063 (7) M ʘ, stellar radii R1 = 0.65 (2) Rʘ, and R2 = 0.90 (1) Rʘ, and luminosities L1 = 0.40 (4) Lʘ and L2 = 0.62 (5) Lʘ. These are in reasonable agreement with the values from Hill et al. (1989). Additional analyses were carried out also using the same RV data but substituting, in turn, the LC datasets of Binnendijk (1955), Duerbeck (1978), Robb and Milone (1982) and Genet et al. (1982). While the four Earthbound LC datasets were of much lower precision than the satellite data, they still yielded reasonable agreement in the final parameters. Additionally, they yielded some insight as to the behaviour of the dark spot (on star 1) over some 75 years. The B and V light curve data of Duerbeck (1978) suggested that the unresolved companion is hot. An updated period study originally presented in Nelson et al. (2014) but now with a Light Time Effect (LiTE) fit is presented. Fifteen new times of minimum from the TESS data were added, requiring only a modest refinement of the LiTE parameters. The intrinsic rate of period change (that is, with the LiTE component removed) is dP/dt = 1.80 (20) x 10−7 seconds/year. If dP/dt can be attributed to conservative mass exchange, the rate would be dM1/dt = -2.33 (26) x 10−7 Mʘ/year. When the fundamental parameters for each star were added to the Log L vs Log T plot for EW-type binaries from Yakut and Eggleton (2005), the results suggested that star 1 of the W-type binary is under-luminous, while the cooler but larger secondary is somewhat evolved. Both are in a marginal contact, typical of W-type eclipsing binaries.

Eclipse timing variations in post-common envelope binaries: Are they a reliable indicator of circumbinary companions?

ABSTRACT Post-common envelope binary systems evolve when matter is transferred from the primary star at a rate that cannot be accommodated by its secondary companion. A common envelope forms, which is subsequently ejected resulting in a system with a binary period frequently between 2 and 3 h. Where circumbinary companions are predicted, it remains unclear whether they form before or after the common envelope ejection. From observations of eclipse timing variations (ETVs), exoplanet data bases e.g. NASA Exoplanet Archive, list typically a dozen systems with confirmed circumbinary planets. Here, we examine seven of these systems, discuss other possible causes, and consider whether, for these dynamic systems, the ETV methodology is a reliable indicator of planetary companions. The systems selected were those where we could determine precise eclipse timings, free from significant extraneous effects such as pulsations, and present 163 new times of minima permitting us to test existing models. Over 30 circumbinary models have been proposed for these seven systems and note that all, other than the latest model for NY Vir, which remains to be fully tested, fail within a year to accurately predict eclipse times. In examining alternative mechanisms, we find that magnetic effects could contribute significantly in two of the seven systems studied. We conclude that the structure of these dynamic systems, with the extreme temperature differences and small binary separations, is not fully understood and that many factors may contribute to the observed ETVs.

Absolute parameters of young stars: V puppis

ABSTRACT New spectrometric data on V Pup are combined with satellite photometry [HIPPARCOS and recent Transiting Exoplanet Survey Satellite (TESS)] to allow a revision of the absolute parameters with increased precision. We find: M1 = 14.0 ± 0.5, M2 = 7.3 ± 0.3 (M⊙); R1 = 5.48 ± 0.18, R2 = 4.59 ± 0.15 (R⊙); T1 26 000 ± 1000, T2 24 000 ± 1000 (K), age 5 ± 1 (Myr), photometric distance 320 ± 10 (pc). The TESS photometry reveals low-amplitude (∼0.002 mag) variations of the β Cep kind, consistent with the deduced evolutionary condition and age of the optical primary. This fact provides independent support to our understanding of the system as in a process of Case A type interactive evolution that can be compared with μ1 Sco. The ∼10 M⊙ amount of matter shed by the overluminous present secondary must have been mostly ejected from the system rather than transferred, thus taking angular momentum out of the orbit and keeping the pair in relative close proximity. New times of minima for V Pup have been studied and the results compared with previous analyses. The implied variation of period is consistent with the Case A evolutionary model, though we offer only a tentative sketch of the original arrangement of this massive system. We are not able to confirm the previously reported cyclical variations having a 5.47-yr period with the new data, though a direct comparison between the HIPPARCOS and TESS photometry points to the presence of third light from a star that is cooler than those of the close binary, as mentioned in previous literature.

International observational campaign of the 2014 eclipse of EE Cephei

Context. EE Cep is one of few eclipsing binary systems with a dark, dusty disc around an invisible object similar to ε Aur. The system is characterised by grey and asymmetric eclipses every 5.6 yr that have significant variations in their photometric depth, ranging from ∼0.m5 to ∼2.m0. Aims. The main aim of the observational campaign of the EE Cep eclipse in 2014 was to test the model of disc precession. We expected that this eclipse would be one of the deepest with a depth of ∼2.m0. Methods. We collected multicoloured observations from almost 30 instruments located in Europe and North America. These photometric data cover 243 nights during and around the eclipse. We also analyzed low- and high-resolution spectra from several instruments. Results. The eclipse was shallow with a depth of 0.m71 in the V band. The multicoloured photometry illustrates small colour changes during the eclipse with a total amplitude of order ∼+0.m15 in the B − I colour index. We updated the linear ephemeris for this system by including new times of minima, measured from the three most recent eclipses at epochs E = 9, 10, and 11. We acquired new spectroscopic observations, covering orbital phases around the eclipse, which were not observed in the past and increased the data sample, filling some gaps and giving better insight into the evolution of the Hα and Na I spectral line profiles during the primary eclipse. Conclusions. The eclipse of EE Cep in 2014 was shallower than expected, measuring 0.m71 instead of ∼2.m0. This means that our model of disc precession needs revision.

First photometric study of two contact binaries: 1SWASP J15133589-3725239, 1SWASP J22310605-1940584

We present the results of our investigation and first analysis of the geometrical and physical parameters of the 1SWASP J15133589-3725239 and 1SWASP J22310605-1940584 W UMa-type binary systems. Light curve analysis was performed with the PHOEBE0.31a interface program based on the Wilson-Devinney code. New times of minima and light elements have been determined. According to our solution, the 1SWASP J15133589-3725239 and 1SWASP J22310605-1940584 binary systems are respectively found to be A- and W-type W UMa systems. We derived the following masses and radii for the components of these eclipsing systems: M1=2.578 M⊙, M2=1.741 M⊙, R1=1.113 R⊙ and R2=0.928 R⊙ for 1SWASP J15133589-3725239 and M1=0.743 M⊙, M2=0.469 M⊙, R1=0.715 R⊙ and R2=0.578 R⊙ for 1SWASP J22310605-1940584. The evolutionary state of the systems is also discussed.

Absolute parameters of three southern eclipsing binaries: DQ Car, BK Ind, and V4396 Sgr

ABSTRACT We present combined photometric and spectroscopic analyses of the three southern eclipsing binary stars: DQ Car, BK Ind, and V4396 Sgr. Radial velocity curves of these three systems were obtained at the South African Astronomical Observatory, and their light curves from the available data bases and surveys were used for the analysis. 75 new times of minima for these three eclipsing binaries were derived, and their ephemerides were updated. Only the O–C diagram of DQ Car indicates a cyclical variation, which was interpreted in terms of the light-time effect due to a third body in the system. Our final models describe these three systems as Algol-like binary stars with detached configurations. The masses and radii were found to be M1 = 1.86(±0.17) M⊙, R1 = 1.63(±0.06) R⊙ and M2 = 1.74(±0.17) M⊙, R2 = 1.52(±0.07) R⊙ for the primary and secondary components of DQ Car; M1 = 1.16(±0.05) M⊙, R1 = 1.33(±0.03) R⊙ and M2 = 0.98(±0.04) M⊙, R2 = 1.00(±0.03) R⊙ for BK Ind; and M1 = 3.14(±0.22) M⊙, R1 = 3.00(±0.09) R⊙ and M2 = 3.13(±0.24) M⊙, R2 = 2.40(±0.08) R⊙ for V4396 Sgr, respectively. The distances to DQ Car, BK Ind, and V4396 Sgr were derived to be 701(±50), 285(±20), and 414(±30) pc from the distance modulus formula, taking into account interstellar extinction. The evolutionary status of these three systems was also studied. It has been found that the components of DQ Car are very young stars at the age of ∼25 Myr and those of BK Ind and V4396 Sgr are evolved main-sequence stars at the ages of ∼2.69 Gyr and ∼204 Myr, respectively.

CK AQR TIME KEEPING. EVIDENCE FOR A THIRD BODY

Photometric measurements of the contact binary system CK Aqr are presented. 49 new times of minimum were obtained between 2005 and 2020. Along with already published observations, this allows the derivation of an improved ephemeris. The resulting O-C diagram shows oscillations which are interpreted as the light time travel effect due to a third component, with a period of 8.2 years.

New Data on the Eclipsing Binary V1848 Ori and Improved Orbital and Light Curve Solutions

Abstract New observations of the eclipsing binary system V1848 Ori were carried out using the V filter resulting in a determination of new times of minima and new ephemeris were obtained. We presented the first complete analysis of the system’s orbital period behavior and analysis of O-C diagram done by the GA and MCMC approaches in OCFit code. The O-C diagram demonstrates a sinusoidal trend in the data; this trend suggests a cyclic change caused by the LITE effect with a period of 10.57 years and an amplitude of 7.182 minutes. It appears that there is a third body with mass function of f (m 3) = 0.0058 M⊙ in this binary system. The light curves were analyzed using the Wilson-Devinney code to determine some geometrical and physical parameters of the system. These results show that V1848 Ori is a contact W UMa binary system with the mass ratio of q = 0.76 and a weak fillout factor of 5.8%. The O’Connell effect was not seen in the light curve and there is no need to add spot.

Period Analysis, Roche Modeling and Absolute Parameters for AU Ser, an Overcontact Binary System

CCD photometric data collected at UnderOak Observatory (UO) and Desert Bloom Observatory (DBO) in three bandpasses (B, V and I_C) produced 10 new times of minimum for AU Ser which were used to revise the linear ephemeris. These results captured in 2011 and 2018 reinforced a longstanding observation that the shape of the light curve from this W UMa binary system (P=0.386497 d) is highly variable. Significantly skewed peaks and differences at maximum light were detected during quadrature which could only be simulated during Roche modeling by positioning a hot spot on the secondary star close to the neck between both constituents. Historically this system has been variously classified as an F8, G5 and K0 system; however, this study supports more recent reports that AU Ser is best described as spectral type K1V-K2V. A fresh assessment of eclipse time residuals over the past 80 years has provided additional insight regarding cyclical changes in orbital period experienced by this interesting variable star.

BVRI Photometric Observations and Study of the Newly Discovered W UMa Type Eclipsing Binary of Multiple System 1SWASP J093010.78+533859.5

New BVRI light curves of the W UMa type eclipsing binary of multiple system 1SWASP J093010.78+533859.5 (GSC 0380-00759) have been constructed based on CCD observations obtained using 1.88 m reflector telescope of KAO, (Kottamia Astronomical Observatory), Egypt on March, 20th in 2013. New times of minima and new ephemeris have been determined from these light curves. Using the Binary Maker 3.0 (BM3) and PHOEBE program, the geometric and photometric element parameters of this system have been derived. Light curve analysis results indicate that J093010B is an overcontact binary with third body shared with 0.056 ± 0.006 of its total luminosity. The filling factor of the system is approximately equal to 17%. According to all available eclipse timings, the preliminary rate of period change has been determined to be -6.35 x 10-5 day/yr. The semi-major axis has been determined as 1.6 ± 0.1 R ⊙.

The contact binary VW Cephei revisited: surface activity and period variation

Context. Despite the fact that VW Cephei is one of the most well-studied contact binaries in the literature, there is no fully consistent model available that can explain every observed property of this system. Aims. Our aims are to obtain new spectra along with photometric measurements, to analyze what kind of changes may have happened in the system in the past two decades, and to propose new ideas for explaining them. Methods. For the period analysis we determined ten new times of minima from our light curves, and constructed a new O–C diagram of the system. Radial velocities of the components were determined using the cross-correlation technique. The light curves and radial velocities were modeled simultaneously with the PHOEBE code. All observed spectra were compared to synthetic spectra and equivalent widths (EWs) of the Hα line were measured on their differences. Results. We re-determine the physical parameters of the system according to our new light curve and spectral models. We confirm that the primary component is more active than the secondary, and there is a correlation between spottedness and the chromospheric activity. We propose that the flip-flop phenomenon occurring on the primary component could be a possible explanation of the observed nature of the activity. To explain the period variation of VW Cep, we test two previously suggested scenarios: the presence of a fourth body in the system, and the Applegate-mechanism caused by periodic magnetic activity. We conclude that although none of these mechanisms can be ruled out entirely, the available data suggest that mass transfer with a slowly decreasing rate provides the most likely explanation for the period variation of VW Cep.

Light Curve Modelling and Evolutionary Status of the Short Period Binary 1SWASP J092328.76+435044

Light curve modeling for the newly discovered system 1SWASP J092328.76+435044 was carried out by using a new BVR complete light curves. A spotted model was applied to treat the asymmetry of the light curves. The output model was obtained by means of Wilson-Devinney code, which reveals that the massive component is hotter than the less massive one with about \Delta T ~ 400K. A total of 8 new times of minima were estimated. The evolutionary state of the system components was investigated based on the estimated physical parameters.

Period variation studies of six contact binaries in M4

We present the first period study of six contact binaries in the closest globular cluster M4 the data collected from June 1995−June 2009 and Oct 2012−Sept 2013. New times of minima are determined for all the six variables and eclipse timing (O-C) diagrams along with the quadratic fit are presented. For all the variables, the study of (O-C) variations reveals changes in the periods. In addition, the fundamental parameters for four of the contact binaries obtained using the Wilson-Devinney code (v2003) are presented. Planned observations of these binaries using the 3.6-m Devasthal Optical Telescope (DOT) and the 4-m International Liquid Mirror Telescope (ILMT) operated by the Aryabhatta Research Institute of Observational Sciences (ARIES; Nainital) can throw light on their evolutionary status from long term period variation studies.

Preliminary elements of the low mass ratio and moderate fill-out factor VSX J045718.3+405643 (GSC 02898–02901)

We present the results of our investigation of the geometrical parameters of the W UMa-type binary system VSX J045718.3+405643 (short name VSX J0457) based on new CCD B, V and Ic light curves.Our observations were carried out during six nights in November and December 2016 using the 0.25 m telescope of the Stazione Astronomica Betelgeuse in Magnago, Northern Italy.Six new times of minima and light elements have been determined and the observed light curves were analysed using the Wilson–Devinney code.The output model reveals that the system is a contact binary of A-Subtype of the W Ursae Majoris systems with a mass ratio of q ∼ 0.26 and a degree of contact factor f ∼ 32%.The primary component is hotter than the secondary by 95 K, this suggests us that the system is under thermal contact.The high orbital inclination (i = 82°.2) implies that VSX J0457 is a total eclipsing binary system and the photometric parameters here obtained are quite reliable.The absolute physical parameters of the two components in VSX J0457 are estimated.Based on these estimated parameters the evolutionary state of the system components is investigated and discussed.Combining our photometric solution with the 3-D correlation obtained for contact binaries by Gazeas (2009) we derive the masses and radii of the components of this eclipsing system as M1 = 1.44M⊙, M2 = 0.38M⊙, R1 = 1.55R⊙ and R2 = 0.87R⊙.The distance to VSX J0457 was calculated as 147 pc from this analysis, taking into account interstellar extinction.

Photometric study of two eclipsing binary stars: Light curve analysis and system parameters for GU CMa and SWASP J011732.10+525204.9

A new photometric study of two eclipsing binary systems (GU CMa and SWASP J011732.10+525204.9) is presented. The accepted solutions of analyzing the light curves revealed that GU CMa is a semi-detached system consisting of two early spectral type components, (B2 and B2.5) while SWASP J011732.10+525204.9 is a contact binary with two late type components (K2 and M1). The primary component of each system is the massive one. The geometric configuration indicates that SWASP J011732.10+525204.9 passes through a very critical phase in which each component exactly fills its limited lobe with zero fill out ratio. New times of minimum and the absolute physical parameters for each system are determined. The evolution status for each system has been investigated.