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A catalogue of chromospherically active binary stars (third edition)
(Wiley-Blackwell, 2008) Eker, Z.; Ak, N. Filiz; Bilir, S.; Dogru, D.; Tueysuez, M.; Soydugan, Esin; Bakis, H.
The catalogue of chromospherically active binaries (CABs) has been revised and updated. With 203 new identifications, the number of CAB stars is increased to 409. The catalogue is available in electronic format where each system has a number of lines (suborders) with a unique order number. The columns contain data of limited numbers of selected cross references, comments to explain peculiarities and the position of the binarity in case it belongs to a multiple system, classical identifications (RS Canum Venaticorum, BY Draconis), brightness and colours, photometric and spectroscopic data, a description of emission features (Ca II H and K, H alpha, ultraviolet, infrared), X-ray luminosity, radio flux, physical quantities and orbital information, where each basic entry is referenced so users can go to the original sources.
Absolute dimensions and apsidal motion of the eccentric binary V731 Cephei
(Oxford Univ Press, 2008) Bakis, V.; Zejda, M.; Bulut, I.; Wolf, M.; Bilir, S.; Bakis, H.; Demircan, O.
A detailed analysis of new and existing photometric, spectroscopic and spatial distribution data of the eccentric binary V731 Cep was performed. Spectroscopic orbital elements of the system were obtained by means of cross-correlation technique. According to the solution of radial velocities with UBVRc and I-c light curves, V731 Cep consists of two main-sequence stars with masses M-1 = 2.577 (0.098) M-circle dot, M-2 = 2.017 (0.084) M-circle dot, radii R-1 = 1.823 (0.030) R-circle dot, R-2 = 1.717 (0.025) R-circle dot and temperatures T-eff1 = 10700 (200) K, T-eff2 = 9265 (220) K separated from each other by a = 23.27 (0.29) R-circle dot in an orbit with inclination of 88 degrees.70 (0.03). Analysis of the O-C residuals yielded a rather long apsidal motion period of U = 10000 (2500) yr compared to the observational history of the system. The relativistic contribution to the observed rates of apsidal motion for V731 Cep is significant (76 per cent). The combination of the absolute dimensions and the apsidal motion properties of the system yielded consistent observed internal structure parameter (log (k) over bar (2,obs) = -2.36) compared to the theory ( log (k) over bar (2,theo) = -2.32). Evolutionary investigation of the binary by two methods (Bayesian and evolutionary tracks) shows that the system is t = 133(26) Myr old and has a metallicity of [M/H] = -0.04(0.02) dex. The similarities in the spatial distribution and evolutionary properties of V731 Cep with the nearby (rho similar to 3 degrees.9) open cluster NGC 7762 suggest that V731 Cep could have been evaporated from NGC 7762.
Age Dependent Angular Momentum, Orbital Period and Total Mass of Detached Binaries
(Cambridge Univ Press, 2012) Demircan, O.; Tuysuz, M.; Soydugan, Faruk; Bilir, S.
The orbital angular momenta OAM (J) of detached binaries (including both cool and hot binaries) were estimated and nine subgroups were formed according to their OAM (3) distribution. The mean kinematical ages of all subgroups have been estimated by using their space velocity distributions and, thus, the age dependent variations of the mean OAM (3), orbital period (13), and total mass (M) of all subgroups were investigated. It was discovered that: i) The orbital period of detached binaries with radiative components decrease very slowly during the main sequence (MS) evolution. It is interesting that the large amount of mass loss is almost balanced by the OAM loss, and not much change in the orbital periods is observed. ii) The nuclear evolution of radiative components beyond the MS initiates the increase of the periods until the components have convective upper layers, i.e. until they become later than F5 IV, and the system becomes a cool binary with sub-giant or giant components. iii) The large co-rotating distance of the magnetically-driven wind in cool binaries (CAB) carries out a large amount of OAM and then the periods of such binaries decrease significantly, and the orbits shrink until another effect such as mass transfer dominates the period changes.
Discovery of ? scuti type oscillations in two algol-type binaries: DY Aqr and Bg Peg
(Hungarian Academy of Sciences (Konkoly Observatory), 2009) Soydugan, Esin; Soydugan, Faruk; Enyuz, T.; Puskullu, Q.; Tuysuz, M.; Bakis, V.; Bilir, S.
[No abstract available]
Discovery of {delta} Scuti type oscillations in two Algol-type binaries: DY Aqr and BG Peg
(2009) Soydugan, Esin; Soydugan, Faruk; Senyüz, T.; Püsküllü, Ç.; Tüysüz, M.; Bakis, V.; Bilir, S.
[No abstract available]
Dynamical evolution of active detached binaries on the log Jo-log M diagram and contact binary formation
(Blackwell Publishing, 2006) Eker, Z.; Demircan, O.; Bilir, S.; Karatas, Y.
Orbital angular momentum (OAM, J(o)), systemic mass (M) and orbital period (P) distributions of chromospherically active binaries (CAB) and W Ursae Majoris (W UMa) systems were investigated. The diagrams of logJ(o)-IogP, logM-logP and logJ(o)-IogM were fortned from 119 CAB and 102 W UMa stars. The log J(o)-Iog M diagram is found to be most meaningful in demonstrating dynamical evolution of binary star orbits. A slightly curved borderline (contact border) separating the detached and the contact systems was discovered on the log J(o)-Iog M diagram. Since the orbital size (a) and period (P) of binaries are determined by their current J(o), M and mass ratio, q, the rates of OAM loss (d log J(o)/dt) and mass loss (d log M/dt) are primary parameters to determine the direction and the speed of the dynamical evolution. A detached system becomes a contact system if its own dynamical evolution enables it to pass the contact border on the log J(o)-log M diagram. The evolution of q for a mass-losing detached system is unknown unless the mass-loss rate for each component is known. Assuming q is constant in the first approximation and using the mean decreasing rates of J(o) and M from the kinematical ages of CAB stars, it has been predicted that 11, 23 and 39 per cent of current CAB stars would transform to W UMa systems if their nuclear evolution permits them to live 2, 4 and 6 Gyr, respectively.
Effective Temperatures of Selected Main-Sequence Stars with the Most Accurate Parameters
(Astronomical Soc Pacific, 2015) Soydugan, Faruk; Eker, Z.; Soydugan, Esin; Bilir, S.; Gokce, E. Y.; Steer, I.; Tuysuz, M.
In this study we investigate the distributions of the properties of detached double-lined binaries (DBs) in the mass luminosity, mass radius, and mass-effective temperature diagrams. We have improved the classical mass luminosity relation based on the database of DBs by Eker et al. (2014a). Based on the accurate observational data available to us we propose a method for improving the effective temperatures of eclipsing binaries with accurate mass and radius determinations.
Empirical bolometric correction coefficients for nearby main-sequence stars in the Gaia era
(Oxford Univ Press, 2020) Eker, Z.; Soydugan, Faruk; Bilir, S.; Bakis, V; Alicavus, F.; Ozer, S.; Aslan, G.
Nearby detached double-lined eclipsing binaries with most accurate data were studied and 290 systems were found with at least one main-sequence component having a metallicity of 0.008 <= Z <= 0.040. Stellar parameters, light ratios, Gaia Data Release 2 trigonometric parallaxes, extinctions and/or reddening were investigated and only 206 systems were selected as eligible to calculate empirical bolometric corrections. NASA/IPAC Galactic dustmaps were the main source of extinctions. Unreliable extinctions at low Galactic latitudes vertical bar b vertical bar <= 5 degrees were replaced with individual determinations, if they exist in the literature, else associated systems were discarded. The main-sequence stars of te remaining systems were used to calculate the bolometric corrections (BCs) and to calibrate the BC-T-eff relation, which is valid in the range 3100-36 000 K. De-reddened (B - V)(0) colours, on the other hand, allowed us to calibrate two intrinsic colour-effective temperature relations; the linear one is valid for T-eff > 10 000 K, while the quadratic relation is valid for T-eff < 10 000 K; that is, both are valid in the same temperature range in which the BC-Teff relation is valid. New BCs computed from Teff and other astrophysical parameters are tabulated, as well.
Evidences on secular dynamical evolution of detached active binary orbits and contact binary formation
(Astronomical Soc Pacific, 2007) Eker, Z.; Demircan, O.; Bilir, S.; Karatas, Y.
Evidence of secular dynamical evolution for detached active binary orbits are presented. First order decreasing rates of orbital angular momentum (OAM), systemic mass (M = M-1 + M-2) and orbital period of detached active binaries have been determined a J/J = 3.48 x 10(-10)yr(-1),M/M = 1.30 x 10(10)yr(-1) and P/P 3.96 x 10(-10)yr(-1) from the kinematical ages of 62 field detached systems. The ratio of d log J/ d log M = 2.68 implies that either there are mechanisms which amplify AM loss delta = 2.68 times with respect to isotropic AM loss of hypothetical isotropic winds or there exist external causes contributing AM loss in order to produce this mean rate of decrease for orbital periods. Various decreasing rates of OAM (d log J /dt) and systemic mass (d log M /dt) determine various speeds of dynamical evolutions towards a contact configuration. According to average dynamical evolution with delta = 2.68, the fraction of 10, 22 and 39 per cent of current detached sample is expected to be contact system within 2, 4 and 6 Gyr respectively.
Formation and evolution of W Ursa Majoris stars: fallacies and corrections
(Wiley-Blackwell, 2008) Eker, Z.; Demircan, O.; Bilir, S.
Period histograms of eclipsing binaries generated with data from the All-Sky Automated Survey cannot be interpreted only using orbital evolution. Eclipse probabilities, selection effects and space distributions in the solar neighbourhood should be considered before any interpretations are made. Depending upon the physical dimensions (the total mass and the period) of the progenitor stars and the efficiency of the angular momentum loss mechanism, a newly formed W Ursa Majoris type binary can be at any age up to several Gyr. Also, the evolution in the contact stage is controlled not only by angular momentum and mass loss but also by mass transfer between the component stars. Thus, the mean life of the contact stages should be about 1.6 Gyr. A different time-scale would cause inconsistencies.
Interrelated main-sequence mass-luminosity, mass-radius, and mass-effective temperature relations
(Oxford Univ Press, 2018) Eker, Z.; Bakis, V.; Bilir, S.; Soydugan, Faruk; Steer, I.; Soydugan, Esin; Bakis, H.
Absolute parameters of 509 main-sequence stars selected from the components of detached eclipsing spectroscopic binaries in the solar neighbourhood are used to study mass-luminosity, mass-radius, and mass-effective temperature relations (MLR, MRR, and MTR). The MLR function is found better if expressed by a six-piece classical MLR (L proportional to M-alpha) rather than a fifth or a sixth degree polynomial within the mass range of 0.179 < M/M-circle dot <= 31. The break points separating the mass ranges with classical MLR do not appear to us to be arbitrary. Instead, the data indicate abrupt changes along the mass axis in the mean energy generation per unit of stellar mass. Unlike the MLR function, the MRR and MTR functions cannot be determined over the full range of masses. A single-piece MRR function is calibrated from the radii of stars with M <= 1.5M(circle dot), while a second single-piece MTR function is found for stars with M > 1.5M(circle dot). The missing part of the MRR is computed from the MLR and MTR, while the missing part of the MTR is computed from the MLR and MRR. As a result, we have interrelated the MLR, MRR, and MTR, which are useful in determining the typical absolute physical parameters of main-sequence stars of given masses. These functions are also useful to estimate typical absolute physical parameters from typical T-eff values. Thus, we were able to estimate the typical absolute physical parameters of main-sequence stars observed in the Sejong Open cluster Survey, based on that survey's published values for T-eff. Since typical absolute physical parameters of main-sequence stars cannot normally be determined in such photometric surveys, the interrelated functions are shown to be useful to compute such missing parameters from similar surveys.
Kinematic Properties of Chromospheric Active Binary Stars
(Cambridge Univ Press, 2012) Tuysuz, M.; Soydugan, Faruk; Bilir, S.; Demircan, O.
The kinematic behaviour of 362 chromospherically active binary stars (CABs) in the solar neighbourhood were investigated. The Third CABs Catalog by Eker et al. (2008) was used as the main source. The spatial distribution and the components of the Galactic space velocities of the programme stars were determined. The effects of differential rotation and Local Standard of Rest (LSR) were corrected for all systems. Forty probable moving group (MG) members were determined by Eggen's criteria. The kinematic age of the young systems, which are probable members of MGs, was calculated as 0.79 (0.21) Gyr and the rest of 322 field stars were found to have a kinematic age of 4.38 (1.1) Gyr. Field CABs were separated into two sub-groups: dwarf systems, which were formed by main sequence (dwarf) stars, and evolved systems included at least one evolved (giant or sub-giant) component. The kinematic age of 134 dwarf systems was calculated as 4.69 (0.75) Gyr and 4.15 (1.29) Gyr for 188 evolved CABs.
MAIN-SEQUENCE EFFECTIVE TEMPERATURES FROM A REVISED MASS-LUMINOSITY RELATION BASED ON ACCURATE PROPERTIES
(Iop Publishing Ltd, 2015) Eker, Z.; Soydugan, Faruk; Soydugan, Esin; Bilir, S.; Gokce, E. Yaz; Steer, I.; Tuysuz, M.
The mass-luminosity (M-L), mass-radius (M-R), and mass-effective temperature (M-T-eff) diagrams for a subset of galactic nearby main-sequence stars with masses and radii accurate to <= 3% and luminosities accurate to <= 30% (268 stars) has led to a putative discovery. Four distinct mass domains have been identified, which we have tentatively associated with low, intermediate, high, and very high mass main-sequence stars, but which nevertheless are clearly separated by three distinct break points at 1.05, 2.4, and 7 M-circle dot within the studied mass range of 0.38-32 M-circle dot. Further, a revised mass-luminosity relation (MLR) is found based on linear fits for each of the mass domains identified. The revised, mass-domain based MLRs, which are classical (L proportional to M-alpha), are shown to be preferable to a single linear, quadratic, or cubic equation representing an alternative MLR. Stellar radius evolution within the main sequence for stars with M > 1 M-circle dot is clearly evident on the M-R diagram, but it is not clear on the M-T-eff diagram based on published temperatures. Effective temperatures can be calculated directly using the well known Stephan-Boltzmann law by employing the accurately known values of M and R with the newly defined MLRs. With the calculated temperatures, stellar temperature evolution within the main sequence for stars with M>1 M-circle dot is clearly visible on the M-T-eff diagram. Our study asserts that it is now possible to compute the effective temperature of a main-sequence star with an accuracy of similar to 6%, as long as its observed radius error is adequately small (<1%) and its observed mass error is reasonably small (<6%).
New absolute magnitude calibrations for detached binaries
(Wiley-V C H Verlag Gmbh, 2008) Bilir, S.; Ak, T.; Soydugan, Esin; Soydugan, Faruk; Yaz, E.; Ak, N. Filiz; Eker, Z.
Lutz-Kelker bias corrected absolute magnitude calibrations for the detached binary systems with main-sequence components are presented. The absolute magnitudes of the calibrator stars were derived at intrinsic colours of Johnson-Cousins and 2MASS (Two Micron All Sky Survey) photometric systems. As for the calibrator stars, 44 detached binaries were selected from the Hipparcos catalogue, which have relative observed parallax errors smaller than 15% (sigma(pi)/pi <= 0.15). The calibration equations which provide the corrected absolute magnitude for optical and near-infrared pass bands are valid for wide ranges of colours and absolute magnitudes: -0.18 < (B - V)(0) < 0.91, -1.6 < M-V < 5.5 and -0.15 < (J - H)(0) < 0.50, -0-02 < (H - K-s)(0) < 0. 13, 0 < M-J < 4, respectively. The distances computed using the luminosity-colours (LCs) relation with optical (B V) and near-infrared (J H K-s) observations were compared to the distances found from various other methods. The results show that new absolute magnitude calibrations of this study can be used as a convenient statistical tool to estimate the true distances of detached binaries out of Hipparcos' distance limit. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA. Weinheim
New absolute magnitude calibrations for W Ursa Majoris type binaries
(Wiley-V C H Verlag Gmbh, 2009) Eker, Z.; Bilir, S.; Yaz, E.; Demircan, O.; Helvaci, M.
Parallaxes of W UMa stars in the Hipparcos catalogue have been analyzed. 31 W UMa stars. which have the most accurate parallaxes (sigma(pi)/pi < 0.15) which are neither associated with a photometric tertiary nor with evidence of a Visual companion, were selected for re-calibrating the Period-Luminosity-Color (PLC) relation of W UMa stars. Using the Lutz-Kelker (LK) bias corrected (most probable) parallaxes. periods (0.26 < P < 0.87, P in days), and colors (0.04 < (B - V)(0) < 1.28) of the 31 selected W UMa, the PLC relation have been revised and re-calibrated. The difference between the old (revised but no( bias corrected) and the new (LK bias corrected) relations are almost negligible in predicting the distances of W UMa stars Up to about 100 pc. But, it increases and may become intolerable as distances of stars increase. Additionally, using (J - H)(0) and (H -K(s))(0) colors from 2MASS (Two Micron All Sky Survey) data, a PLC relation working with infrared data was derived. It can be used with infrared colors in the range -0.01 < (J-H)(0) < 0.58, and -0.10 < (H - K(s))(0) < 0.18. Despite of the fact that the 2MASS data refer to single epoch observations which are not guaranteed to be taken at maximum brightness of the W UMa stars. the established relation has been found surprisingly consistent and reliable in predicting LK corrected distances of W UMa stars. (C) 2009 WILEY-VCH Verlag GmbH & Co, KGaA, Weinheim
New Discovered Pulsational Components in Algol Type Binaries and their Positions on the plane of Porb-Ppuls
(Astronomical Soc Pacific, 2010) Soydugan, Esin; Soydugan, Faruk; Senyuz, T.; Tuysuz, M.; Bakis, V.; Bilir, S.; Cicek, C.
In this study, eclipsing binaries located in the delta Scuti region of the instability strip were chosen from the list of candidate eclipsing binary systems with delta Scuti components. These candidate systems were photometrically observed and some of them were announced to be new Algol-type binaries with delta Scuti components. Although the pulsational variability could not be determined for some of the candidate Algols, pulsational components in EW Boo and DY Aqr have been discovered for the first time. The light curves of EW Boo and DY Aqr were analyzed to model the variations caused by the eclipsing behavior and then we determined the pulsational periods and amplitudes of the pulsating components in these Algols. The relationship between the pulsation and orbital periods of the eclipsing binaries were tested and discussed for the cases of EW Boo and DY Aqr.
Spatial distribution and galactic model parameters of cataclysmic variables
(Elsevier Science Bv, 2008) Ak, T.; Bilir, S.; Ak, S.; Eker, Z.
The spatial distribution, galactic model parameters and luminosity function of cataclysmic variables (CVs) in the solar neighbourhood have been determined from a carefully established sample of 459 CVs. The sample contains all of the CVs with distances computed from the period-luminosity-colours (PLCs) relation of CVs which has been recently derived and calibrated with 2MASS photometric data. It has been found that an exponential function fits best to the observational z-distributions of all of the CVs in the sample, non-magnetic CVs and dwarf novae, while the sech(2) function is more appropriate for nova-like stars and polars. The vertical scaleheight of CVs is 158 +/- 14 pc for the 2MASS J-band limiting apparent magnitude of 15.8. On the other hand, the vertical scaleheights are 128 +/- 20 and 160 +/- 5 pc for dwarf novae and nova-like stars, respectively. The local space density of CVs is found to be similar to 3 x 10(-5) pc(-3) Which is in agreement with the lower limit of the theoretical predictions. The luminosity function of CVs shows an increasing trend toward higher space densities at low luminosities, implying that the number of short-period systems should be high. The discrepancies between the theoretical and observational population studies of CVs will almost disappear if for the z-dependence of the space density the sech(2) density function is used. (C) 2007 Elsevier B.V. All rights reserved.
STUDY OF ECLIPSING BINARY AND MULTIPLE SYSTEMS IN OB ASSOCIATIONS. II. THE CYGNUS OB REGION: V443 Cyg, V456 Cyg, AND V2107 Cyg
(Iop Publishing Ltd, 2014) Bakis, V.; Hensberge, H.; Bilir, S.; Bakis, H.; Yilmaz, F.; Kiran, E.; Demircan, O.
Three presumably young eclipsing binary systems in the direction of the Cygnus OB1, OB3, and OB9 associations are studied. Component spectra are reconstructed and their orbits are determined using light curves and spectra disentangling techniques. V443 Cyg and V456 Cyg have circular orbits while the light curve of V2107 Cyg imposes a slightly eccentric orbit (e = 0.045 +/- 0.03). V443 Cyg harbors F-type stars, not young early-A stars as previously suggested in the literature based solely on photometry. It appears to be situated in the foreground (distance 0.6 +/- 0.2 kpc) of the young stellar populations in Cygnus. V456 Cyg, at a distance of 0.50 +/- 0.03 kpc, consists of a slightly metal-weak A-type star and an early-F star. The age of both systems, on or very near to the main sequence, remains uncertain by an order of magnitude. V2107 Cyg is a more massive system (8.9 +/- 2 and 4.5 +/- 1.2M(circle dot)) at 1.5 +/- 0.5 kpc and, also kinematically, a strong candidate-member of Cyg OB1. The more massive component is slightly evolved and appears to undergo non-radial beta Cep-type pulsations. The Doppler signal of the secondary is barely detectable. A more extensive, asteroseismological study is necessary to fix masses more precisely. Nevertheless, the position of the primary in the H-R diagram confines the age reasonably well to 20 +/- 5 Myr, indicating that for Cyg OB1 has a similar extent of star formation history as that established for Cyg OB2.
The Catalogue of Stellar Parameters from the Detached Double-Lined Eclipsing Binaries in the Milky Way
(Cambridge Univ Press, 2014) Eker, Z.; Bilir, S.; Soydugan, Faruk; Gokce, E. Yaz; Soydugan, Esin; Tuysuz, M.; Senyuz, T.
The most accurate stellar astrophysical parameters were collected from the solutions of the light and the radial velocity curves of 257 detached double-lined eclipsing binaries in the Milky Way. The catalogue contains masses, radii, surface gravities, effective temperatures, luminosities, projected rotational velocities of the component stars, and the orbital parameters. The number of stars with accurate parameters increased 67% in comparison to the most recent similar collection by Torres, Andersen, & Gimenez (2010). Distributions of some basic parameters were investigated. The ranges of effective temperatures, masses, and radii are 2 750 < T-eff (K)< 43 000, 0.18 < M/M-circle dot < 33, and 0.2 < R/R-circle dot < 21.2, respectively. Being mostly located in one kpc in the Solar neighborhood, the present sample covers distances up to 4.6 kpc within the two local Galactic arms, Carina-Sagittarius and Orion Spur. The number of stars with both mass and radius measurements better than 1% uncertainty is 93, better than 3% uncertainty is 311, and better than 5% uncertainty is 388. It is estimated from the Roche lobe filling factors that 455 stars (88.5% of the sample) are spherical within 1% of uncertainty.
The early-type near-contact binary system V337 Aql revisited
(Elsevier Science Bv, 2014) Tuysuz, M.; Soydugan, Faruk; Bilir, S.; Soydugan, Esin; Senyuz, T.; Yontan, T.
The close binary V337 Aql consists of two early B-type components with an orbital period of 2.7339 d. New multi-band photometric observations of the system together with published radial velocities enabled us to derive the absolute parameters of the components. The simultaneous light and radial velocity curves solution yields masses and radii of M-1 = 17.44 +/- 0.31 M-circle dot and R-1 = 9.86 +/- 0.06 R-circle dot for the primary and M-2 = 7.83 +/- 0.18 M-circle dot and R-2 = 7.48 +/- 0.04 R-circle dot for the secondary component. Derived fundamental parameters allow us to calculate the photometric distance as 1355 +/- 160 pc. The present analysis indicates that the system is a near-contact semi-detached binary, in which a primary star is inside its Roche lobe with a filling ratio of 92% and the secondary star fills its Roche lobe. From O-C data analysis, an orbital period decrease was determined with a rate of -7.6 x 10(-8) yr(-1). Kinematic analysis reveals that V337 Aql has a circular orbit in the Galaxy and belongs to a young thin-disc population. (C) 2013 Elsevier B.V. All rights reserved.

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