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Öğe A comprehensive photometric study of the Algol-type eclipsing binary: BG Pegasi(Elsevier Science Bv, 2011) Soydugan, Esin; Soydugan, Faruk; Senyuz, T.; Puskullu, C.; Demircan, O.This study presents new photometric observations of classical Algol type binary BC Peg with a delta Scuti component The light curve modeling was provided with the physical parameters of the component stars in the BC Peg system for the first time After modeling light curves in B and V filters, the eclipse and proximity effects were removed from the light curve to analyze intrinsic variations caused by the hotter component of the system Frequency analysis of the residuals light represents the multi-mode pulsation of the more massive component of the BC Peg system at periods of 0.039 and 0 047 clays Two frequencies could be associated with non-radial (l = 2) modes The total amplitude of the pulsational variability in the V light curve was found to be about 0 045 mag The long-term orbital period variation of the system was also investigated for the first time The O-C analysis indicates periodic variation superimposed on a downward parabola The secular period variation means that the orbital period of the system is decreasing at a rate of -5 5 seconds per century, probably due to the magnetic activity of the cooler component. The tilted sinusoidal O-C variation may be caused by the gravitational effect of an unseen component around the system (C) 2010 Elsevier B V All rights reservedÖğe Analysis of the exoplanet containing system Kepler-13(Springer, 2018) Budding, E.; Puskullu, C.; Rhodes, M. D.We have applied the close binary system analysis program WINFITTER, with its physically detailed fitting function, to an intensive study of the complex multiple system Kepler-13 using photometry data from all 13 short cadence quarters downloaded from the NASA Exoplanet Archive (NEA) (http://exoplanetarchive.ipac.caltech.edu ). The data-point error of our normalized, phase-sequenced and binned (380 points per bin: 0.00025 phase interval) flux values, at 14 ppm, allows the model's specification for the mean reference flux level of the system to a precision better than 1 ppm. Our photometrically derived values for the mass and radius of KOI13.01 are 6.8 +/- 0.6 M-J and 1.44 +/- 0.04 R-J. The star has a radius of 1.67 +/- 0.05 R-circle dot. Our modelling sets the mean of the orbital inclination i at 94.35 +/- 0.14 degrees, with the star's mean precession angle phi(p) -49.1 +/- 5.0 degrees and obliquity theta(o) 67.9 +/- 3.0 degrees, though there are known ambiguities about the sense in which such angles are measured. Our findings did not confirm secular variation in the transit modelling parameters greater than their full correlated errors, as argued by previous authors, when each quarter's data was best-fitted with a determinable parameter set without prejudice. However, if we accept that most of the parameters remain the same for each transit, then we could confirm a small but steady diminution in the cosine of the orbital inclination over the 17 quarter timespan. This is accompanied by a slight increase of the star's precession angle less negative), but with no significant change in the obliquity of its spin axis. There are suggestions of a history of strong dynamical interaction with a highly distorted planet rotating in a 3:2 resonance with its revolution, together with a tidal lag of similar to 30 deg. The mean precessional period is derived to be about 1000 y, but at the present time the motion of the star's rotation axis appears to be supporting the gravitational torque, rather than providing the balance against it that would be expected over long periods of time. The planet has a small but detectable backwarming effect on the star, which helps to explain the difference in brightness just after transit and just before occultation eclipses. In assessing these findings it is recognized that sources of uncertainty remain, notably with possible inherent micropulsational effects, variations from other components of the multiple star, stellar activity, differential rotation and the neglect of higher order terms (than r(1)(5)) in the fitting function, where r(1) is the ratio of the radius of the star to the mean orbital separation of planet and host star.Öğe Analysis of the exoplanet containing system Kepler-91(Springer, 2016) Budding, E.; Puskullu, C.; Rhodes, M. D.; Demircan, O.; Erdem, A.We have applied the graphical user interfaced close binary system analysis program WINFITTER to an intensive study of Kepler-91 using all the available photometry from the NASA Exoplanet Archive (NEA) at the Caltech website: http://exoplanetarchive.ipac.caltech.edu. Our fitting function for the tidal distortion derives from the relevant Radau equation and includes terms up to the fifth power of the fractional radius. This results in a systematic improvement in the mass ratio estimation over that of Lillo-Box et al. (Astron. Astrophys. 562:A109, 2014a) and our derived value for the mass ratio is in close agreement with that inferred from recent high-resolution spectroscopic data. It is clear that the data analysis in terms of simply an eclipsing binary system is compromised by the presence of significant other causes of light variation, in particular non-radial pulsations. We apply a low-frequency filtering procedure to separate out some of this additional light variation. Whilst the derived eccentricity appears then reduced, an eccentric effect remains in the light curve. We consider how this may be maintained in spite of likely frictional effects operating over a long time. There are also indications that could be associated with Trojan or other period-resonant mass concentrations. Suggestions of a possible secular period variation are briefly discussed.Öğe Photometric analysis of the system Kepler-1(Springer, 2016) Budding, E.; Rhodes, M. D.; Puskullu, C.; Ji, Y.; Erdem, A.; Banks, T.We have applied the close binary system analysis program WINFITTER to an intensive study of Kepler-1 (= TrES-2) using all the available photometry (14 quarters; 1570640 measures) from the NASA Exoplanet Archive (NEA) at the Caltech website http://exoplanetarchive.ipac.caltech.edu. The mean individual data-point error of the normalized flux values is 0.00026, leading to the model's specification for the mean reference flux of the system to an accuracy of similar to 0.5 ppm. Completion of the analysis requires a number of prior quantities, relating mainly to the host star, that are adopted from relevant literature. Our new results tend broadly to confirm those of previous authors, though there are a number of significant differences. Specifically, the applied photometric fitting function is more precise than those used before on the full Kepler data-set. The more complete discussion of the interdependent role of errors, using MCMC sampling, allows greater confidence in the obtained parameters themselves as well as understanding or their likely errors. Our photometrically derived values for the mass and radius of Kepler-1b are 1.18 +/- 0.05 M-Jup and 1.21 +/- 0.05 R-Jup. The mass of this Safronov Class I planet is closer to published spectroscopic values than found from previous photometric analysis, which can be attributed to the improved fitting function. The analysis determines a definite photometric Doppler effect from the orbit, but this is not independent of the tidal ('ellipticity') effect, and the two are consistently combined in our fitting function. A corresponding rotation-related Rossiter effect was not detected, allowing an upper limit on the rotation speed of similar to 70 kms(-1). The proportion of light coming from the known companion star is resolved, but turns out rather less than that inferred from the results of direct measurement. The fitting function also predicts a small secondary minimum ('occultation'), when the light reflected by the planet is eclipsed. However, the occultation depth cannot be measured directly from the data to the relevant accuracy, and so models for the planet's atmospheric properties based on this will be compromised by other assumptions and approximations in the light curve's fitting function. Suggestions of secular trends for the variation of parameters are considered, but the evidence of the Kepler data is not yet very persuasive.Öğe Photometric investigation of hot exoplanets: TrES-3b and Qatar-1b(Elsevier Science Bv, 2017) Puskullu, C.; Soydugan, Faruk; Erdem, A.; Budding, E.New photometric follow-up observations of transitting 'hot Jupiters' TrES-3b and Qatar-1b are presented. Weighted mean values of the solutions of light curves in R-filter for both planetary systems are reported and compared with the previous results. The transit light curves were analysed using the WINFITTER code. The physical properties of the planets were estimated. The planet radii are found to be R-p = 1.381 +/- 0.033R(J) for TrES-3b and R-p = 1.142 +/- 0.025R(J) for Qatar-1b. Transit times and their uncertainties were also determined and a new linear ephemeris was computed for both systems. Analysis of transit times showed that a significant signal could not be determined for TrES-3b, while weak evidence was found for Qatar-1b, which might be tested using more precise future transit times. (C) 2017 Elsevier B.V. All rights reserved.Öğe Photometric Study of Hot Jupiters: WASP-10 b and HAT-P-36 b(Astronomical Soc Pacific, 2015) Puskullu, C.; Soydugan, Faruk; Erdem, A.; Budding, E.; Soydugan, Esin; Tuysuz, M.; Rhodes, M.This work presents preliminary results of WINFITTER analyses of photometric observations of two hot Jupiters, WASP-10 b and HAT-P-36 b. According to these results, HAT-P-36 b has mean radius of R-p = 1.40 +/- 0.25 R-Jup, and transit parameter b = 0.44 +/- 0.09. WASP-10b shows some additional variations, and we therefore preferred to model its transit light curve with and without probable spot variations.Öğe The Galactic kinematics of cataclysmic variables(Springer, 2015) Ak, T.; Bilir, S.; Ozdonmez, A.; Soydugan, Faruk; Soydugan, Esin; Puskullu, C.; Ak, S.Kinematical properties of CVs were investigated according to population types and orbital periods, using the space velocities computed from recently updated systemic velocities, proper motions and parallaxes. Reliability of collected space velocity data was refined by removing 34 systems with largest space velocity errors. The 216 CVs in the refined sample were shown to have a dispersion of 53.70 +/- 7.41 kms(-1) corresponding to a mean kinematical age of 5.29 +/- 1.35 Gyr. Population types of CVs were identified using their Galactic orbital parameters. According to the population analysis, seven old thin disc, nine thick disc and one halo CV were found in the sample, indicating that 94 % of CVs in the Solar Neighbourhood belong to the thin-disc component of the Galaxy. Mean kinematical ages 3.40 +/- 1.03 and 3.90 +/- 1.28 Gyr are for the nonmagnetic thin-disc CVs below and above the period gap, respectively. There is not a meaningful difference between the velocity dispersions below and above the gap. Velocity dispersions of the non-magnetic thin-disc systems below and above the gap are 24.95 +/- 3.46 and 26.60 +/- 4.18 kms(-1), respectively. This result is not in agreement with the standard formation and evolution theory of CVs. The mean kinematical ages of the CV groups in various orbital period intervals increase towards shorter orbital periods. This is in agreement with the standard theory for the evolution of CVs. Rate of orbital period change was found to be dP/dt =-1.62(+/- 0.15) x10(-5) sec yr(-1).Öğe TOWARD UNDERSTANDING THE NATURE OF THE YOUNG DETACHED BINARY SYSTEM HD 350731(Iop Publishing Ltd, 2015) Soydugan, Faruk; Alicavus, F.; Bilir, S.; Soydugan, Esin; Puskullu, C.; Senyuz, T.The young binary system HD 350731 is a noteworthy laboratory for studying early-type binaries with similar components. We present here an analysis of differential multi-color photometric and spectroscopic observations of the double-lined detached system. Accurate absolute parameters were determined for the first time from a simultaneous solution of the light and radial velocity curves. HD 350731 consists of two B8V-type components with masses and radii, respectively, of M-1= 2.91 +/- 0.13 M-circle dot, M-2= 2.80 +/- 0.14 M-circle dot, R-1= 2.11 +/- 0.05 R-circle dot, and R-2= 2.07 +/- 0.05 R-circle dot. The effective temperatures were determined based on analysis of disentangled spectra of the components and were derived to be 12,000 +/- 250 and 11,830 +/- 300 K for the primary and secondary components, respectively. The measured projected rotational velocities, 69.2 +/- 1.5 km s(-1) for the primary and 70.1 +/- 1.7 km s-1 for the secondary, were found to be closer to the pseudo-synchronous velocities of the components. Comparison with evolutionary models suggests an age of 120 +/- 35 Myr. Kinematic analysis of the unevolved binary system HD 350731 revealed that it belongs to the young thin-disk population of the Galaxy.Öğe Transit modelling of selected Kepler systems(Springer, 2019) Huang, Q. Y.; Banks, T.; Budding, E.; Puskullu, C.; Rhodes, M. D.This paper employs a simple model, considering just geometry and linear or quadratic limb darkening, to fit Kepler transit data via a Markov Chain Monte Carlo (MCMC) methodology for Kepler-1b, 5b, 8b, 12b, 77b, 428b, 491b, 699b, 706b, and 730b. Additional fits were made of the systems using the more sophisticated modeller Winfitter, which gives results in general agreement with the simpler model. Analysis of data with longer integration times showed biasing of the derived parameters, as expected from the literature, leading to larger estimates for radii and reducing estimates of the system inclination.
