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Absolute Parameters of Detached Binaries in the Southern Sky - I: V349 Ara and V4403 Sgr
(Cambridge Univ Press, 2015) Erdem, A.; Surgit, D.; Engelbrecht, C. A.; Van Heerden, H. P.
We present the first analysis of spectroscopic and photometric observations of the two southern eclipsing binary stars, V349 Ara and V4403 Sgr. Radial velocity curves of these two systems obtained at the South African Astronomical Observatory and their V light curves from the All Sky Automated Survey were solved simultaneously using the Wilson-Devinney code. Our photometric models describe these two systems as Algol-like binary stars with detached configurations. The masses and radii were found to be 2.59 +/- 0.07 M, 3.60 +/- 0.07 R and 2.51 +/- 0.06 M, 4.15 +/- 0.07 R for the primary and secondary components of V349 Ara, respectively. Those of V4403 Sgr were derived to be 1.33 +/- 0.02 M, 1.74 +/- 0.02 R and 1.59 +/- 0.03 M, 2.50 +/- 0.03 R for the primary and secondary components, respectively. The distances to V349 Ara and V4403 Sgr were computed to be 677 +/- 36 and 199 +/- 10 pc from the dynamic parallax, respectively, taking into account interstellar extinction. The evolution cases of these two systems are also examined. Both components of these two systems are evolved main-sequence stars, and the dynamic ages were estimated as approximately 0.67 and 2.29 Gyr for V349 Ara and V4403 Sgr, respectively, when compared to Geneva theoretical evolution models.
Absolute parameters of detached binaries in the southern sky - III: HO Tel
(Elsevier Science Bv, 2017) Surgit, D.; Erdem, A.; Engelbrecht, C. A.; van Heerden, H. P.; Manick, R.
We present the first radial velocity analysis of the southern eclipsing binary star HO Tel, based on spectra obtained at the South African Astronomical Observatory in 2013. The orbital solution of this neglected binary gave the quite large spectroscopic mass ratio of 0.921(+/- 0.005). The V light curve from the All Sky Automated Survey (ASAS) and Walraven five-colour (WULBV) photometric light curves (Spoelstra and Van Houten 1972) were solved simultaneously using the Wilson-Devinney code supplemented by the Monte Carlo search method. The final photometric model describes HO Tel as a detached binary star where both component stars fill about three-quarters of their Roche limiting lobes. The masses and radii were found to be 1.88(+/- 0.04) M-circle dot, 2.28(+/- 0.15) R-circle dot and 1.73(+/- 0.04) M-circle dot, 2.08(+/- 0.16) R-circle dot for the primary and secondary components of the system, respectively. The distance to HO Tel was calculated as 282(+/- 30) pc, taking into account interstellar extinction. The evolution case of HO Tel was also examined. Both components of the system are evolved main-sequence stars with an age of approximately 1.1 Gy, when compared to Geneva theoretical evolution models. (C) 2017 Elsevier B.V. All rights reserved.
Absolute parameters of eclipsing binaries in Southern Hemisphere sky - II: QY Tel
(Elsevier Science Bv, 2016) Erdem, A.; Surgit, D.; Engelbrecht, C. A.; van Heerden, H. P.; Manick, R.
This paper presents the first analysis of spectroscopic and photometric observations of the neglected southern eclipsing binary star, QY Tel. Spectroscopic observations were carried out at the South African Astronomical Observatory in 2013. New radial velocity curves from this study and V light curves from the All Sky Automated Survey were solved simultaneously using modern light and radial velocity curve synthesis methods. The final model describes QY Tel as a detached binary star where both component stars fill at least half of their Roche limiting lobes. The masses and radii were found to be 1.32 (+/- 0.06) M-circle dot, 1.74 (+/- 0.15) R-circle dot and 1.44 (+/- 0.09) M-circle dot, 2.70 (+/- 0.16) R-circle dot for the primary and secondary components of the system, respectively. The distance to QY Tel was calculated as 365 (+/- 40) pc, taking into account interstellar extinction. The evolution case of QY Tel is also examined. Both components of the system are evolved main-sequence stars with an age of approximately 3.2 Gy, when compared to Geneva theoretical evolution models. (C) 2016 Elsevier B.V. All rights reserved.
Absolute parameters of southern detached eclipsing binary: HD 53570
(Elsevier Science Bv, 2018) Surgit, D.
In this study, we conducted the first analysis of spectroscopic and photometric observations of the eclipsing binary star HD 53570. Spectroscopic observations of HD 53570 were made at the Sutherland Station of the South African Astronomical Observatory in 2013 and 2014. The radial velocities of the components were determined using the cross-correlation technique. The spectroscopic mass ratio obtained for the system was 1.13 (+/- 0.07). The All Sky Automated Survey V light curve of HD 53570 was analyzed using the Wilson-Devinney code combined with the Monte Carlo search method. The final model showed that HD 53570 has a detached configuration. The mass and radii of the primary and secondary components of HD 53570 were derived as 1.06 (+/- 0.07) M-circle dot, 1.20 (+/- 0.16) M-circle dot, and 1.42 (+/- 0.14) R-circle dot, 2.07 (+/- 0.16) R-circle dot, respectively. The distance of HD 53570 was computed as 248 (38) pc considering interstellar extinction. The evolutionary status of the component stars was also investigated using Geneva evolutionary models.
Absolute parameters of southern eclipsing binary: MW Pup
(Elsevier Science Bv, 2015) Surgit, D.; Erdem, A.; Engelbrecht, C. A.
This paper presents the first analysis of spectroscopic and photometric observations of the southern eclipsing binary star MW Pup. ASAS V light and SAAO radial velocity curves of the system were solved simultaneously using Wilson-Devinney code. The results describe MW Pup as an Algol-like binary star with a detached configuration. The masses of the components were found to be 2.20 +/- 0.06 and 1.88 +/- 0.07 M-circle dot and the radii to be 1.84 +/- 0.03 and 1.72 +/- 0.03 R-circle dot for primary and secondary components, respectively. The distance to MW Pup was calculated to be 430 +/- 30 pc from the dynamic parallax, neglecting interstellar absorption, in agreement with the value derived from the eclipse-parallax method. The evolution of the system is also discussed. Both components are unevolved Main Sequence stars and the dynamic age of the system is estimated as 263 +/- 70 My when compared to theoretical evolution models. (C) 2014 Elsevier B.V. All rights reserved.
Absolute parameters of young stars: HX Velorum
(Oxford Univ Press, 2019) Blackford, M. G.; Erdem, A.; Surgit, D.; Ozkardes, B.; Budding, E.; Butland, R.; Demircan, O.
We present combined photometric and spectroscopic analyses of the southern multiple star HX Vel. High-resolution spectra of this system were taken at the University of Canterbury Mt. John Observatory in the years 2009-2015. Absolute parameters for HX Vel tend to confirm its young and near-main-sequence nature. We specify the main adopted parameters of the (non-eclipsing) close binary as follows: M-1 = 8.5 +/- 1.7, M-2 = 5.4 +/- 1.2, R-1 = 5.0 +/- 0.3, R-2 = 3.1 +/- 0.2, (circle dot); T-1 25 000 +/- 1300, T-2 20 000 +/- 2500 (K); systemic M-V -4.2 +/- 0.2. These parameters are sensitive to the low inclination, where we find a small disparity between the photometrically optimal 28 +/- 2 degrees and an adopted value of 26 degrees that gives better consistency with main-sequence stellar modelling. The relationship of HX Vel to the galactic cluster IC 2395 and OB association Vela OB1C is also considered, in the context of photometric parallaxes found for HX Vel and other cluster members.
Absolute parameters of young stars: V454 Carinae
(Oxford Univ Press, 2019) Butland, R. J.; Erdem, A.; Ozkardes, B.; Blackford, M. G.; Surgit, D.; Budding, E.; Demircan, O.
We present combined photometric and spectroscopic analyses of the multiple star V454 Carinae. High-resolution spectra of the system were taken at the University of Canterbury Mt. John Observatory during the years 2008-18. These have been processed using generic and purpose-built software. New digital single lens reflex photometry of the system has also been collected and similarly analysed. Absolute parameters for the three main stars confirm V454 Car's young and near-Main-Sequence nature. We find: M-1 = 4.6 +/- 0.4, M-2 = 4.4 +/- 0.4, M-3 = 4.5 +/- 0.5, R-1 = 2.83 +/- 0.18, R-2 = 2.74 +/- 0.16, R-3 = 2.78 +/- 0.16 (circle dot); T-1 similar to 17 500, T-2 similar to 15 500, T-3 similar to 15 000 (K), age similar to 30 Myr, photometric distance similar to 500 (pc). The major component V454 Car A is the close binary identified by the HIPPARCOS satellite. This binary and component B appear to be in eccentric orbits about a common centre of gravity with a period of similar to 1900 d. Analysis of the radial velocity curves suggests that the mass of component B is greater than that of its visible member. Measured radial velocities of this visible star show irregularities with a time-scale of about a week. The galactic location, proper motions, and age of V454 Car support the runaway nature proposed by others, and the combined results are consistent with a dynamical ejection scenario from the Vela region of Gould's Belt relatively soon after the stars' formation.
First detailed study of two eccentric eclipsing binaries: TYC 5378-1590-1 and TYC 8378-252-1
(Edp Sciences S A, 2023) Zasche, P.; Surgit, D.; Erdem, A.; Engelbrecht, C. A.; Marang, F.
Aims. The analysis of combined photometry and spectroscopy of eccentric eclipsing binary systems facilitates the derivation of very precise values for a large ensemble of physical parameters of the component stars and their orbits, thereby providing stringent tests of theories of stellar structure and evolution. In this paper two eccentric eclipsing binary systems, TYC 5378-1590-1 and TYC 8378252-1, are studied in detail for the first time. Methods. Radial velocities were obtained using cross-correlation methods applied to mid-resolution spectra covering almost the entire orbital phase domains of these two systems. TESS photometry was used for the analysis of TYC 5378-1590-1, whereas ASAS-SN photometry was used for the analysis of TYC 8378-252-1. Results. We obtained the first precise derivation of the physical parameters of these systems. Both systems display moderately eccentric orbits (e similar to 0:3 and 0:2) with periods of 3.73235 and 2.87769 days, respectively. The apsidal motion is very slow, with a duration of several centuries for both systems. We present two models for the apsidal motion of TYC 5378-1590-1. The internal structure constant derived from observations for TYC 8378-252-1 is approximately 11% lower than theoretical predictions. We discuss possible reasons for this discrepancy. Our analysis indicates that the components of both systems are on the main sequence. The components of TYC 5378-1590-1 are relatively young stars (age similar to 600 Myr) close to the ZAMS, whereas the components of TYC 8378-252-1 are relatively old stars (age similar to 4 Gyr) close to the TAMS. Our finding that the circularization timescale for TYC 5378-1590-1 is similar to 200 times longer than its evolutionary age is compatible with circularization theory; however, our finding that the evolutionary age of TYC 8378-252-1 is approximately ten times longer than the circulation age, while its orbital eccentricity is quite high (e similar to 0:2), challenges the present theories of circularization.
First Photometric is Study of Two Southern Eclipsing Binaries IS Tel and DW Aps
(Amer Inst Physics, 2017) Ozer, S.; Surgit, D.; Erdem, A.; Ozturk, O.
The paper presents the first photometric analysis of two southern eclipsing binary stars, IS Tel and DW Aps. Their V light curves from the All Sky Automated Survey were modelled by using Wilson-Devinney method. The final models give these two Algol-like binary stars as having detached configurations. Absolute parameters of the components of the systems were also estimated.
First Spectroscopic Solutions of Two Southern Eclipsing Binaries: HO Tel and QY Tel
(Astronomical Soc Pacific, 2015) Surgit, D.; Erdem, A.; Engelbrecht, C. A.; van Heerden, P.; Manick, R.
We present preliminary results from the analysis of spectroscopic observations of two southern eclipsing binary stars, HO Tel and QY Tel. The grating spectra of these two systems were obtained at the Sutherland Station of the South African Astronomical Observatory in 2013. Radial velocities of the components were determined by the Fourier disentangling technique. Keplerian radial velocity models of HO Tel and QY Tel give their mass ratio as 0.921 +/- 0.005 and 1.089 +/- 0.007, respectively.
First Spectroscopic Study of the Southern Eclipsing Binary V454 Carina
(Astronomical Soc Pacific, 2015) Ozkardes, B.; Erdem, A.; Surgit, D.; Butland, R.; Budding, E.
We present preliminary results from the analysis of spectroscopic observations of the southern eclipsing binary star V454 Car (HIP 36682). High-resolution spectra of the system were taken at the Mt. John University Observatory in 2009, 2010, 2011, and 2014. Detailed examination of the spectra indicates that V454 Car is a triple system. Radial velocities of the components of the eclipsing pair were obtained. The orbital solution gave quite a large spectroscopic mass ratio of q(spec) = 0.93 +/- 0.05.
Light Curve Analysis of Southern Detached Binary: CPD-79 92
(Amer Inst Physics, 2018) Ozer, S.; Surgit, D.
This paper presents the first photometric solution of CPD-79 92 (GSC 09370-00140 = TYC 9370-140-1 = ASAS J030739-7856.5, V=10.32 mag). The ASAS V light curve of the system was analyzed using Wilson and Devinney code. The photometric mass ratio of the system was derived with q-search method. Then, the absolute parameters of system were estimated.
Neglected reverse Algol system: WZ Hor
(Elsevier Science Bv, 2012) Surgit, D.; Erdem, A.
This paper presents the first analysis of spectroscopic and photometric observations of the eclipsing binary star WZ Hot. Observations of the system were made at the Mt. John University Observatory in 2007. Since the light contribution of the secondary component was merely 2-3% of the total light of the system in the optical wavelengths, the radial velocity of the primary component could only be determined using the cross-correlation method. A single-lined spectroscopic orbital solution of WZ Hor was obtained, and the BVRI light curves of the system and radial velocity curve of the primary component were analysed simultaneously using the Wilson-Devinney method. The results describe WZ Hor as a reverse Algol-like binary star with a detached configuration. The following absolute parameters of the components were also derived: M-1 = 1.51 +/- 0.03 M-circle dot, M-2 = 0.66 +/- 0.01 M-circle dot, R-1 = 1.62 +/- 0.02 R-circle dot, R-2 = 0.66 +/- 0.01 R-circle dot, L-1 = 4.93 +/- 0.64 L-circle dot and L-2 = 0.09 +/- 0.02 L-circle dot. The distance to WZ Nor was calculated as 95 +/- 8 pc using distance modulus with correction for interstellar extinction, in agreement with the HIPPARCOS value. (C) 2011 Elsevier B.V. All rights reserved.
NR Peg: A new highly active semi-detached binary
(Elsevier, 2014) Erdem, A.; Surgit, D.; Kurpinska-Winiarska, M.; Oblak, E.
This paper presents the first analysis of spectroscopic and photometric observations of the eclipsing binary star NR Peg. ELODIE H alpha observations indicate that the secondary component is a chromospherically active star; however, the spectral line profiles (especially of neutral metals) of NR Peg are very wide and have a complex structure with asymmetric bubbles on its branches, which could be interpreted as traces of stellar magnetic activity in both components. The 2007 and 2008 BVR light curves are generally those of beta Lyrae-type eclipsing binaries, however, there are large asymmetries between maxima. We explained these peculiar asymmetries in terms of large dark spots on the primary component. ELODIE spectroscopic data and 2008 BVR light curves were solved simultaneously using Wilson-Devinney code. The results describe NR Peg as a RS CVn type binary star with a semi-detached configuration. The masses of the components were found to be 1.60 +/- 0.03 M-circle dot, and 0.57 +/- 0.02 M-circle dot and the radii to be 3.35 +/- 0.07 R-circle dot and 3.55 +/- 0.08 R-circle dot for the primary and secondary components, respectively. Both components of NR Peg appear to have evolved behind the terminal age main sequence. However, the less-massive secondary component is significantly oversized and overluminous compared to theoretical evolution models. The distance of NR Peg was calculated as 138 +/- 12 pc, taking into account interstellar extinction, in agreement with the HIPPARCOS value. (C) 2014 Elsevier B.V. All rights reserved.
Orbital Periods of Two Algol-Type Binaries: AV Cep and GI Cep
(Amer Inst Physics, 2018) Apak, B.; Erdem, A.; Ozturk, O.; Gozutok, M. I.; Surgit, D.
Results are presented of the orbital period analysis of two Algol-type binary stars (AV Cep and GI Cep). All available minima times in the literature together with minima times obtained in this study were used. The orbital period changes were investigated using the O-C method. O-C diagrams of both systems show upward parabolic variations, which indicate that the orbital period of these two systems is increasing secularly. The rate of period increase of AV Cep and GI Cep was calculated to be 0.415 +/- 0.016 s/year and 0.026 +/- 0.009 s/year, respectively. These secular period increases could be explained in terms of mass transfer from the secondary component to the primary component according to the classic Algol scenario.
Photometric Study of Two Detached Binaries FW Vel and BB Mon
(Amer Inst Physics, 2017) Ozer, S.; Surgit, D.
We present the first analysis of photometric observations of two detached binary stars, FW Vel and BB Mon. Their V light curves from the All Sky Automated Survey were solved using Monte Carlo Search Method. The final solutions describe these two systems as Algol-like binary stars with detached configurations. The absolute parameters of the components of the systems were also estimated.
Photometric Study of Two Neglected Beta Lyr-Type Binaries: V342 Her & V387 Her
(Amer Inst Physics, 2017) Aktoka, U.; Erdem, A.; Ozturk, O.; Surgit, D.
In this study, SuperWASP light curves of V342 11cr and V387 Her were analyzed by means of the Wilson Devinney (W-D) code with a Monte Carlo (MC) search method for the first time. The final photometric solutions of these two systems show that while V342 Her has an over contact configuration in which both components overtlows their Roche limiting lobes, V387 Her has a detached configuration. Photometric mass ratios and approximate absolute parameters of the systems are obtained.
The Algol binary system KZ Pavonis revisited
(Wiley-Blackwell, 2010) Surgit, D.; Erdem, A.; Budding, E.
We present results from analysing new spectroscopic and photometric observations of the KZ Pav (IDS 20490-7048 A-BC) multiple system. High-resolution spectra were taken at the Mt John University Observatory in 2007 and 2008. Radial velocities for the close binary were determined from cross-correlation and spectral disentangling methods. The resulting orbital elements are a(1) sin i = 0.0103 +/- 0.0001 au, a(2) sin i = 0.0158 +/- 0.0001 au, M(1) sin3i = 1.598 +/- 0.006 M(circle dot) and M(2) sin3i = 1.045 +/- 0.006 M(circle dot). The close binary components rotated synchronously according to their Mg i (5183.6 A) line profiles. Four photometric data sets (1988-89 BV, 1998 V, Hipparcos and 2006 BVRI) were modelled with modern light-curve synthesis methods. The radial velocity models, including proximity effects, give the close binary mass ratio as 0.641 +/- 0.003. The combination of the photometric light and radial velocity data gives the following absolute parameters: M(1) = 1.70 +/- 0.02 M(circle dot), M(2) = 1.09 +/- 0.03 M(circle dot), R(1) = 1.74 +/- 0.01 R(circle dot), R(2) = 1.94 +/- 0.02 R(circle dot), L(1) = 5.86 +/- 0.81 L(circle dot) and L(2) = 2.32 +/- 0.40 L(circle dot). The distance to KZ Pav is 115 +/- 8 pc from our analysis, taking into account interstellar extinction. The orbital period of the close binary, from times of minimum data covering nearly one century, indicates a quasi-sinusoidal form superimposed on a downward parabola. The secular period decrease was interpreted in terms of the combined effects of mass transfer and loss. The sinusoidal component may reflect a light-time effect from either an unseen component or higher order terms in perturbations from the BC system, or perhaps an internal magnetic field rearrangement (Applegate type) mechanism. The orbits of the A-BC and B-C systems are considered against historic astrometric measurements.
The First Spectroscopic Study of Southern Binary:HD 53570
(Amer Inst Physics, 2016) Surgit, D.
In this study, I present the first analysis of spectroscopic observations of southern detached eclipsing binary star HD 53570. The spectroscopic observations of HD 53570 was made at the Sutherland Station of the South African Astronomical Observatory (SAAO) in 2013 and 2014. Radial velocities (RVs) of the components of HD 53570 were determined by cross-correlation technique (CCT). The H beta (4861.36 angstrom) lines of the components of HD 53570 were chosen as the most suitable lines for reliable RV measurements. The resulting orbital elements of HD 53570 is calculated as, a(1) sin i = 0.0258 +/- 0.0005 AU, a(2) sin i = 0.0228 +/- 0.0005 AU, M-1 sin(3)i = 1.035 +/- 0.046 M-circle dot and M-2 sin(3)i = 1.167 +/- 0.050 M-circle dot. The radial velocity models of HD 53570 give the close binaries mass ratio as 1.13 +/- 0.07.

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