Photometric Mass Ratio Research Articles

A new eclipsing binary system with a pulsating component detected by CoRoT

Die Serie Communications in Asteroseismology (CoAst) stellt eine international gefragte Plattform für wissenschaftliche Publikationen der neuesten Forschungsergebnisse auf dem Gebiet der Asteroseismologie dar. Forschungsgegenstand der Asteroseismologie sind veränderliche und pulsierende Sterne. Neben den halbjährlich erscheinenden regulären Ausgaben mit Beiträgen aus der laufenden Forschung werden auch Sonderausgaben für Konferenzberichte bzw. Programmhandbücher herausgegeben. Contents Scaled oscillation frequencies and ´echelle diagrams as a tool for comparative asteroseismology, by T. R. Bedding and H. Kjeldsen; Photometric observations and frequency analysis of the Delta Scuti star IP UMa, by D. Sinachopoulos, P. Gavras, Chr. Ducourant; Photometric and Spectroscopic Study of the Delta Scuti Stars FH Cam, CU CVn and CC Lyn, by G. J. Conidis, K. D. Gazeas, C. C. Capobianco, W. Ogloza; A comparison of Bayesian and Fourier methods for frequency determination in asteroseismology, by T. R.White, B. J. Brewer, T. R.Bedding, D. Stello and H.Kjeldsen; A new eclipsing binary system with a pulsating component detected by CoRoT; by K. Sokolovsky, C.Maceroni, M.Hareter, C.Damiani, L. Balaguer-N´u˜nez, and I.Ribas

The ROSAT bright source 1RXS J201607.0 + 251645: an active Algol-type binary

1RXS J201607.0+251645 is identified as an eclipsing binary. We present preliminary observations in the V band with the 0.6-m telescope for three years and extensive observations in the V and R bands with the 0.8-m telescope for six nights, respectively. The light curve of the system is EB type. Five light minimum times were obtained and the orbital period of 0.388058d(±0.00044d) is determined. The photometric solution given by the 2003-version of the Wilson–Devinney program suggests that the binary is a semidetached system with photometric mass ratio 0.895(±0.006), which is probably comprised of a G5 primary and an oversized K5 secondary. The less massive component has completely filled its Roche lobe, while the other one almost fills its Roche lobe with a filling factor of 93.4%. The system shows a varying O'Connell effect in its phase folded diagrams from 2005 to 2007, and is X-ray luminous with log LX/Lbol ∼ −3.27. Possible mechanisms to account for these two phenomena are discussed. Finally, we infer that the binary may be in thermal oscillation or may evolve into a contact binary.

Radial velocity mapping of Paczyński's star AW UMa: not a contact binary

Abstract We present 2D (radial velocity, orbital phase) spectroscopic results for the very low mass-ratio close binary AW UMa which strongly indicate that the spectroscopic mass ratio (qsp= 0.10) does not agree with the photometrically derived one and that the widely adopted contact binary model appears to experience serious inconsistencies and limitations for this object. AW UMa is compared with V566 Oph (qsp= 0.26) which we found to behave according to the contact model. Observed broadening functions of AW UMa can be interpreted by a very strong limb darkening and/or non-solid-body rotation of the dominant primary component; the former assumption is unphysical while the differential rotation is not supported by an apparent stability of localized, dark features on the outer side of the primary. There are indications of the existence of an equatorial belt encompassing the whole system. All deficiencies in the interpretation and the discrepancy between the photometric and spectroscopic mass ratio of AW UMa can be solved within a new model of AW UMa where both components are detached and the system is submerged in a stream of hot, optically thick matter which mimics the stellar contact. While the masses and their ratio are correctly given by spectroscopy, the photometric picture is heavily modified by the matter engulfing both stars in the equatorial plane.

Photometric Studies of Twelve Deep, Low-mass Ratio Overcontact Binary Systems

The formations of the blue straggler stars and the FK Com-type stars are unsolved problems in stellar astrophysics. One of the possibilities for their formations is from the coalescence of W UMa-type overcontact binary systems. Therefore, deep (f > 50%), low-mass ratio (q 50%), low-mass ratio (q < 0.25) overcontact binary stars. We found that the system GSC 619-232 has the highest degree of overcontact (f = 93.4%). The derived photometric mass ratio of V857 Her, q = 0.0653, indicates that it is the lowest-mass ratio system among W UMa-type binaries.

BVRI Light Curves and Period Analysis of the Beta Lyrae System XX Leonis

AbstractThe contact eclipsing binary system XX Leonis (p = 0.97 days, Sp A9) has been analysed using the PHOEBE programme, based on the Wilson–Devinney code. The BVRI light curves were obtained during spring 2006 using the 20-cm telescope and ST-7 CCD detector. The effective temperature of the primary component determined from the photometric analysis is T = (7342 ± 14) K, the inclination of the orbit is i = (84.83 ± 0.29)° and the photometric mass ratio q = (0.40 ± 0.01). The third-body hypothesis was also suggested; based on a period analysis using 57 minimum times this gave a period for the third body of p3 = (59.66 ± 0.05) yr, an amplitude of A = (0.036 ± 0.028) day and zero eccentricity, which yields as a minimum mass M3,min = (0.91 ± 0.01) M⊙.

Close Binary Star Observables: Modeling Innovations 2003-06

AbstractInnovative work on close binary models in 2003-06 improved upon synthesized line spectra, line profiles, and polarimetry; developed new ways of parameter estimation; and increased solution effectiveness and efficiency. Recent applications demonstrate the analytic power of binary system line spectrum models that pre-date the triennium. X-ray binary line profiles and radial velocity curves were refined by solution of the radiative transfer problem with specific inclusion of X-irradiation. Model polarization curves were generated by Monte Carlo experiments with multiple Thomson scattering in thin and thick binary system disks. In the parameter estimation area, independent developments by two groups now allow measurement of ephemerides, apsidal motion, and third body parameters from whole light and velocity curves, to supplement the traditional way of eclipse timings. Although the new route to those parameters is not well known within the ephemeris community, there are accuracy advantages and the number of applications is increasing. Numerical solution experiments on photometric mass ratios have checked two views of their intuitive basis, and show that mass ratios are well determined where star radii and limiting lobe radii are both well determined, which is for semi-detached or over-contact binaries with total-annular eclipses. Solution efficiency and automatic operation is needed for processing of light curves from large surveys, and will also be valuable for preliminary solutions of individually observed binaries. Neural networks have mainly been used for classification, and now a neural network program reliably finds preliminary solutions for W UMa binaries. Archived model light curves and Fourier fitting also are being pursued for classification and for preliminary solutions. Light curves in physical units such as erg·sec−1·cm−3 now allow direct distance estimation by combining the absolute accuracy of model stellar atmospheres with the astrophysical detail of a physical close binary model, by means of rigorous scaling between surface emission and observable flux. A Temperature-distance (T-d) theorem specifies conditions under which temperatures of both stars and distance can be found from light and velocity curves.

Photometric Studies of Bright Southern Binary Systems: ε Cra and ψ Ori

We present results from detailed analyses of new data combined with previously published light curves of ε Cra and ψ Ori. Based on the shape of the secondary minimum of ε CrA we found that the discrepancy between the photometric and spectroscopic mass ratio, although marginal, is statistically significant. We propose a third light as a possible solution and derive the absolute parameters of components. The physical parameters of components of the early-type binary system ψ Ori were also obtained from the light curve modelling. Our solution indicate that ψ Ori is a detached, grazing-eclipse system.

Deep, Low Mass Ratio Overcontact Binary Systems. IV. V410 Aurigae and XY Bootis

The complete charge-coupled device (CCD) light curves in the V, R, and I bands for the eclipsing binary V410 Aur were observed at the Yunnan Observatory in China. Four new light minimum times of V410 Aur were derived from new observations. The photometric solution for V410 Aur was obtained for the first time, while the orbital elements for XY Boo ( observed by Binnendijk in 1971) were reanalyzed by using the latest Wilson-Devinney code. The third light contributions to the total lights of the two binaries are obtained. The results reveal that both systems are A-subtype W UMa binaries with low mass ratios and deep degrees of overcontact (i.e., q(ph) = 0.1428 and f = 52.4% for V410 Aur, and q(ph) = 0.1855 and f = 55.9% for XY Boo). The photometric mass ratios of the two binaries are very consistent with the spectroscopic mass ratios. By combining the spectroscopic elements with our photometric solutions, the absolute photometric parameters for V410 Aur and XY Boo are ( re) determined. Analyzing the orbital periods of the two binaries, it is discovered that their orbital periods show continuous period increases, suggesting that the systems are undergoing mass transfer from the less massive component to the more massive one through the inner Lagrangian point L-1. This kind of binary, with a low mass ratio, a deep degree of overcontact, and a continuous period increase, may coalesce into a rapidly rotating single star due to tidal instability.

WZ And, a probable contact system with mass ratio very close to unity

We present B and V time-series CCD photometry of the short-period eclipsing binary WZ And. Eight new epochs of minimum light were determined from the observations covering five primary and three secondary eclipses. Refined period and new ephemeris are given for the system based on the photoelectric and CCD photometric times of minima obtained in the recent 20 years. A period study covering 100 years or nearly 59,000 orbital cycles reveals a cyclic but not periodic behavior of long-term period variations. Two major period jumps can be indicated. That could be evidence for the existence of a very eccentric third body of the eclipsing system. The light curve shows continuous light changes outside eclipses in both V and B band, indicating that it could be of EW rather EB type. A simultaneous solution of the two light curves was computed using the Wilson–Devinney code. The solution indicates that WZ And is in shallow contact with a fill-out factor of ∼6%. A photometric mass ratio of q = 1.00 ± 0.01 was derived for the system. Discussions on the period behavior and the probable evolutionary status of the system suggest that WZ And could very probably be a newly formed equal-mass contact system.

Photometric study of the light curve of the neglected eclipsing binary FU Ara

The unique (1954–1956) photoelectric B and V light curves of the EB-type eclipsing variable FU Ara are here analyzed. The Wilson-Devinney Differential Correction program was used and the analysis of the results shows that the best fit was obtained at photometric mass ratio q = 0.399 and inclination i = 83°, the primary minimum shows a transit. The star is a semi-detached system with the secondary that accurately fills its limiting lobe. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

New observations, photometric study and preliminary elements of the W UMa system DF CVn

CCD (V) light curve of the EW-type eclipsing variable DF CVn was obtained during seven nights in April–May, 2004. With our data we were able to determine 4 new times of minimum light. The light curve appears to exhibit a typical O'Connell effect, with Maximum I brighter than Maximum II by 0.013 mag. in V. TwoWilson-Devinney (WD) code working sessions, using the V light curve, were done with and without spots. The analysis of the results shows that the best fit was obtained with the spotted solution and indicates contact geometry. The photometric mass ratio of the system is found to be q = 0.347 and its inclination i = 72°, the primary minimum shows a transit. The star may be classified as an A-type W Uma system. Assuming a reasonable value for the mass of the primary component an estimate of the absolute elements of DF CVn has been made, with the assumption that the primary has a mass corresponding to its spectral type according to Straizys and Kuriliene (1981). (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Photometric Mass Ratios of Eclipsing Binary Stars

Photometric Mass Ratios of Eclipsing Binary Stars

Photometric Study of AH Cancri, a W UMa-Type System in M67

We present time-series CCD photometry of AH Cnc, a W UMa–type binary system in the old open cluster M67. Over 3500 measurements in two filters were recorded on 15 nights from 2001 to 2004. From the data, 17 new times of minima for the eclipsing binary were obtained, from which a new ephemeris was derived. The orbital period of the system is refined as 0.36045754 days. A photometric analysis for the obtained light curves is performed based on the Wilson-Devinney code. The photometric solutions reveal a totally eclipsing contact configuration for AH Cnc. The photometric mass ratio is determined to be 0.149 ± 0.002. The masses and radii of the components are estimated as 1.21 ± 0.08 M⊙ and 1.36 ± 0.03 R⊙ for the primary and 0.18 ± 0.02 M⊙ and 0.62 ± 0.02 R⊙ for the secondary, respectively. The evolutionary status of the contact system is briefly discussed.

Improved astrophysical parameters for the overcontact binary FG Hydrae

Photometric data on FG Hya obtained in 2002 and 2004 are presented. Three data sets show the exchange between A-type, W-type and the variable O'Connell effects. The photometric mass ratio (q = 0.1115 +/- 0.0003) derived from B and V light curves is almost the same as the spectroscopic mass ratio (q(sp) = 0.112 +/- 0.004). The new photometric solutions reveal that FG Hya is a deep overcontact binary system ( f = 85.6 +/- 1.8 per cent) with a spotted massive component. A period investigation, based on all available photoelectric or CCD times of light minimum, shows that the O-C curve of FG Hya can be explained as a combination of a secular period decrease and a cyclic variation with a period of 36.4 yr and an amplitude of 0.0289 d. By comparing the variation of the depth of the primary minimum with the change of the cyclic period, it is discovered that both of them may vary with the same cycle length of 36.4 yr and in the same phase. The variation of the light curve, the spotted primary component and the connection between the cyclic period change and the depth of the primary minimum, all may suggest that the G0-type component displays solar-type magnetic activity with a 36.4-yr cycle length. The long-time period decrease is interpreted by mass transfer from the more massive component to the less massive one or/and angular momentum loss due to mass outflow from the outer Lagrangian point.

First light curve and period study of LO Andromedae

New BV light curves and times of minimum light for the short period W UMa system LO And were analyzed to derive the preliminary physical parameters of the system. The light curves were obtained at Ankara University Observatory during 5 nights in 2003. A new ephemeris is determined for the times of primary minimum. The analysis of the light curves is made using the Wilson-Devinney 2003 code. The present solution reveals that LO And has a photometric mass ratio q = 0.371 and is an A-type contact binary. The period of the system is still increasing, which can be attributed to light-time effect and mass transfer between the components. With the assumption of coplanar orbit of the third body the revealed mass is M3 = 0.21M⊙. If the period change dP/dt = 0.0212 sec/yr is caused only by the mass transfer between components (from the lighter component to the heavier) the calculated mass transfer rate is dm/dt = 1.682×10−7M⊙/yr. The absolute radii and masses estimated for the components, based on our photometric solution and the absolute parameters of the systems which have nearly same period are R1 = 1.30R⊙, R2 = 0.85R⊙, M1 = 1.31M⊙, M2 = 0.49M⊙ respectively for the primary and secondary components. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Infrared Differential Photometry of Selected Orbital Binaries

AbstractHigh-angular resolution observations were acquired for a sample of F-G and K nearby orbital binaries, making use of the ADONIS instrument mounted at the 3.6m ESO telescope from La Silla observatory. The aim is to derive broad-band near-infrared colours for the individual components of those binaries which do not fit well the mean mass-luminosity relation, but which have accurate parallaxes (from the Hipparcos satellite) and high-quality orbits, thanks to many previous efforts. Such colour determinations allow component temperatures and photometric mass ratios to be derived.

Semi-detached binaries as probes of the Local Group

Evolutionary and distance estimation issues for eclipsing binaries (EBs) are examined in the context of spin-off from gravitational lens surveys and the GAIA mission. The OGLE survey shows a major deficiency of normal Algol type binaries in the Small Magellanic Cloud. Statistical analysis coupled with further observing will be needed to decide if the Algol shortfall is an evolutionary effect connected with low metallicity or is only apparent. Distances estimated for EBs are directly physical, with no need for calibration via nearby examples with known distances (EB distance indicators are therefore not standard candles, contrary to common usage of the name). Only the best examples will be needed for distances, given the enormous numbers of EBs expected from GAIA, so one can be very selective. Accordingly the relative merits of detached (DB), semi-detached (SD), and overcontact (OC) EBs are discussed, with emphasis on under-recognized advantages of SDs and OCs. Included are considerations of orbital eccentricity, morphology, photometric mass ratios, observing efficiency, aliasing of radii, and practicality.

KR Cygni: a near-contact eclipsing binary?

In this study we present photometric observations of the eclipsing binary KR Cyg made in 1999 and 2000. The observations of the eclipsing binary KR Cyg have been carried out in B, V and R colours at the Ege University Observatory. A new seasonal light curves are presented. New times of minima and ephemerides are given. Based on a statistical analysis of the times of minima obtained by photoelectric photometry, the orbital period of the system is found to be constant. The photometric mass ratio of the system is well determined. The corresponding light curves were analyzed by the Wilson-Devinney code.

Long-term photometric study of the W UMa binary star V523 Cas

We present a long-term photoelectric and charge-coupled device (CCD) photometric study of the short-period W UMa star V523 Cas made from 1986 to 2000. The orbital-period changes and light-curve variations of the binary system are studied. 47 new times of minima are obtained from our data. A period study covering more than 43 000 cycles based on the photoelectric and CCD photometric times of minima confirms the long-term, secular period changes of the system. It is found that the orbital period has been continuously increasing in the past three decades at a rate of dP/dt = 8.84 × 10 −8 dy r −1 . No cyclic period variations are found from our result. Eight V and five B completely covered light curves are formed from the observations made in eight epochs. The light curves are of W UMa type and show marked asymmetries with unequal maxima. The differences between the two maxima in each light curve appear to be cyclic over a time-scale of about 8 yr. Based on a one-spot model, the light curves are analysed with the Wilson‐Devinney code. The photometric solutions reveal a W-subtype, contact configuration for V523 Cas. The photometric mass ratio is found to be 0.51, and the

Up-to-dateUBVlight and O–C curves analyses of the eclipsing binary V477 Cygni

New and complete UBV light curves and times of minimum are presented for the Algol–type eclipsing binary V477 Cygni (Sp. A3 V+F5 V, mv =8.5, days). The binary orbit of the system is highly eccentric and the system shows an apsidal motion. Using the Wilson-Devinney method, two photometric models, without (MODEL A) and with (MODEL B) third–body light contribution to the total light of the system, are obtained. Period analysis also gives some slender evidence for the unseen third-body in the system with the orbital period of about 157 years. In the MODEL A approximation the apsidal motion period is obtained to be 371 years while it is about 434 years in the MODEL B approximation. The photometric mass ratio () is in good agreement with the spectroscopic value given by Popper (1968). The masses we obtained are and and the radii are and for the primary and secondary components, respectively. Absolute dimensions have been compared with the models using a moderate amount of convective overshooting and mass loss given by Claret & Giménez (1991). In the log M – log R diagram both components are located above but close to the ZAMS. It is possible to say from the log Te – log L diagram that the secondary component is just coming to the main sequence while the primary is slightly evolved from the ZAMS. The theoretical evolutionary models give an age of yrs for the system.