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Öğe Absolute parameters of young stars: PU Pup(IOP Publishing, 2021) Erdem, Ahmet; Sürgit, Derya; Banks, Timothy S.; Özkardeş, Burcu; Budding, EdwinWe present combined photometric and spectroscopic analyses of the southern binary star PU Pup. High-resolution spectra of this system were taken at the University of Canterbury Mt. John Observatory in the years 2008 and again in 2014-15. We find the light contribution of the secondary component to be only ∼2% of the total light of the system in optical wavelengths, resulting in a single-lined spectroscopic binary. Recent TESS data revealed grazing eclipses within the light minima, though the tidal distortion, examined also from HIPPARCOS data, remains the predominating light curve effect. Our model shows PU Pup to have the more massive primary relatively close to filling its Roche lobe. PU Pup is thus approaching the rare ‘fast phase’ of interactive (Case B) evolution. Our adopted absolute parameters are as follows: M1 = 4.10 (±0.20) M , M2 = 0.65 (±0.05) M , R1 = 6.60 (±0.30) R , R2 = 0.90 (±0.10) R ; T1 = 11500 (±500) K, T2 = 5000 (±350) K; photometric distance = 186 (±20) pc, age = 170 (±20) My. The less-massive secondary component is found to be significantly oversized and overluminous compared to standard Main Sequence models. We discuss this discrepancy referring to heating from the reflection effect.Öğe BVRI Photometric Observations, Light Curve Solutions and Orbital Period Analysis of BF Pav(IOP Publishing, 2021) Poro, Atila; Aliçavuş, Fahri; Fernandez-Lajus, Eduardo; Davoudi, Fatemeh; MirshafieKhozani, PegahSadat; Blackford, Mark G.; Budding, Edwin; Jalalabadi, Behjat Zarei; Rahimi, Jabar; Farahani, Farzaneh AhangaraniA new ephemeris, period change analysis and light curve modeling of the W UMa-type eclipsing binary BF Pav are presented in this study. Light curves of the system taken in BVRI filters from two observatories, in Australia and Argentina, were modeled using the Wilson-Devinney code. The results of this analysis demonstrate that BF Pav is a contact binary system with a photometric mass ratio q = 1.460 +/- 0.014, a fillout factor f = 12.5%, an inclination of 87.97 +/- 0.45 deg and a cold spot on the secondary component. By applying the distance modulus formula, the distance of BF Pav was calculated to be d = 268 +/- 18 pc which is in good agreement with the Gaia EDR3 distance. We obtain an orbital period increase at a rate of 0.142 s century(-1) due to a quadratic trend in the O - C diagram. Also, an alternative sudden period jump probably occurred which could be interpreted as a rapid mass transfer from the lower mass star to its companion of about Delta M = 2.45 x 10(-6) M (circle dot). Furthermore, there is an oscillatory behavior with a period of 18.3 +/- 0.3 yr. Since BF Pav does not seem to have significant magnetic activity, this behavior could be interpreted as the light-time effect caused by an undetected third body in this system. In this case, the probability for the third body to be a low mass star with M >= 0.075 M (circle dot) or a brown dwarf is 5.4% and 94.6% respectively. If we assume i ' = 90 degrees, a (3) = 8.04 +/- 0.33 AU. The mass of the secondary component was also determined following two different methods which result close to each other.Öğe Comparative study of the W UMa type binaries S Ant and ? CrA(Cambridge Univ Press, 2024) Bakis, Volkan; Budding, Edwin; Erdem, Ahmet; Love, Tom; Blackford, Mark G.; Wu, Zihao; Tang, AdamContact binaries challenge contemporary stellar astrophysics with respect to their incidence, structure, and evolution. We explore these issues through a detailed study of two bright examples: S Ant and epsilon CrA, that permit high-resolution spectroscopy at a relatively good S/N ratio. The availability of high-quality photometry, including data from the TESS satellite as well as Gaia parallaxes, allows us to apply the Russell paradigm to produce reliable up-to-date information on the physical properties of these binaries. As a result, models of their interactive evolution, such as the thermal relaxation oscillator scenario, can be examined. Mass transfer between the components is clearly evidenced, but the variability of the O'Connell effect over relatively short-time scales points to irregularities in the mass transfer or accretion processes. Our findings indicate that S Ant may evolve into an R CMa type Algol, while the low mass ratio of epsilon CrA suggests a likely merger of its components in the not-too-distant futureÖğe Effects of Opacity on Stellar Radii and Their Relevance to Observational Data(Tubitak Scientific & Technological Research Council Turkey, 2008) Inlek, Guelay; Boeke, Aysun; Yilmaz, Oktay; Budding, EdwinWe have examined the effect of varying opacities on envelope structure with the aid of Paczynski's public domain stellar modelling programs. For this, we prepared new opacity tables from the data of Kurucz [1], using Lagrange interpolation to obtain the tabular values. We compare the results of these Kurucz opacities with similar tabulations from Huebner et al. [2], Iglesias and Rogers [3], Rogers and Iglesias [4] and Iglesias and Rogers [5]. We have checked calculations for the same ranges of stars considered originally by Schwarzschild [6], and compared our findings, using newer opacity data, with those of other sources. We consider how such calculations relate to high accuracy observational data, with the well-observed planetary eclipsing system V 376 Peg (HD 209458), providing a guideline towards data of similar accuracy in the near future. Current accuracies on absolute radii and masses derivable from eclipsing spectroscopic binaries are conservatively estimated at similar to 1%. The effects of revised opacity calculations on the radii of stars of intermediate mass are several times greater than this (5-10% for constant values of other parameters), so that eclipsing binary data should have good potential for independent tests of opacity theory across a wide range of stellar types.Öğe Exoplanet system Kepler-2 with comparisons to Kepler-1 and 13(Springer, 2020) Rhodes, Michael D.; Puskullu, Caglar; Budding, Edwin; Banks, Timothy S.We have carried out an intensive study of photometric (Kepler Mission) and spectroscopic data on the system Kepler-2 (HAT-P-7A) using the dedicated software WinFitter 6.4. The mean individual data-point error of the normalized flux values for this system is 0.00015, leading to the model's specification for the mean reference flux to an accuracy of similar to 0.5 ppm. This testifies to the remarkably high accuracy of the binned data-set, derived from over 1.8 million individual observations. Spectroscopic data are reported with the similarly high-accuracy radial velocity amplitude measure of similar to 2 m s(-1). The analysis includes discussion of the fitting quality and model adequacy. Our derived absolute parameters for Kepler-2 are as follows: Mp (Jupiter) 1.80 +/- 0.13; R1.46 +/- 0.08x106 km; Rp km. These values imply somewhat larger and less condensed bodies than previously catalogued, but within reasonable error estimates of such literature parameters. We find also tidal, reflection and Doppler effect parameters, showing that the optimal model specification differs slightly from a 'cleaned' model that reduces the standard deviation of the similar to 3600 binned light curve points to less than 0.9 ppm. We consider these slight differences, making comparisons with the hot-Jupiter systems Kepler-1 (TrES-2) and 13. We confirm that the star's rotation axis must be shifted towards the line of sight, though how closely depends on what rotation velocity is adopted for the star. From joint analysis of the spectroscopic and photometric data we find an equatorial rotation speed of 11 +/- 3 km s(-1). A slightly brighter region of the photosphere that distorts the transit shape can be interpreted as an indication of the gravity effect at the rotation pole; however we note that the geometry for this does not match the spectroscopic result. We discuss this difference, rejecting the possibility that a real shift in the position of the rotation axis in the few years between the spectroscopic and photometric data-collection times.Alternative explanations are considered, but we conclude that renewed detailed observations are required to help settle these questions.Öğe Near-resonant diurnal reactions: a physical model applicable to origin of life processes(Tubitak Scientific & Technological Research Council Turkey, 2012) Budding, Edwin; Akı, Cüneyt; Demircan, Osman; Gunduz, Bulent; Gunduz, Gungor; Ozel, Mehmet EminWe adopt that the large residual chemical potential energy (CPE) among reagents of the biosphere constitutes the key physical problem posed by life. We associate the formation of this CPE with the near-resonant behaviour of a two-stage 'A-B' molecular process that behaves as a self-sustaining parametric oscillator. Under suitable conditions, such an oscillator generates CPE when forced by a periodic (daily) insolation. The net growth factor required to explain the current mean excess of biospheric CPE is similar to 5x10(-12) d(-1). This aligns with the mean exponential coefficient of secular oxygen generation in the terrestrial atmosphere. It is also consistent with a feasible scale of oxygen production in certain prebiotic natural photosynthesis scenarios, that can be candidates for the initial A subprocess on the Earth. We schematize initial evolutionary development of the A-B process, including the important role of the intermediate AB compound that provides negative feedback. Supportive C-type molecules also develop as a by-product. The diurnally related distribution of H2O2 on Mars may illustrate a comparable proto-biospheric scheme, and there may be analogous processes on Jupiter. The exponential growth in the lengths of terrestrial nucleotide chain molecules also supports its validity, as does the corresponding growth in measures of cellular complexity. We compare the scenario's implications with biological evidence on the possible co-evolution of blue-light photoreception and circadian timing in Archean photoautotrophs. We consider how a surviving level of cellular organization of circadian rhythmicity, from ancient through to modern times, may be interpreted along these lines, comparing our model with a previously published, comparable, biochemical one.Öğe New Spectroscopic Solution of the Eclipsing Binary HX Vel A(Astronomical Soc Pacific, 2015) Surgit, Derya; Erdem, Ahmet; Ozkardes, Burcu; Butland, Roger; Budding, EdwinWe present a preliminary analysis of new spectroscopic observations of the southern binary HX Vel A. High-resolution spectroscopic observations were made at the Mt. John University Observatory in 2014. Radial velocities for HX Vel A were determined from the Gaussian profile-fitting method. The Keplerian radial velocity model gives the close binary mass ratio as 0.57 +/- 0.06. The resulting orbital elements are ai sin i = 0.0086 +/- 0.0003 au, a(2) sin i = 0.0151 +/- 0.0003 au, M-1 sin(3) i = 0.887 +/- 0.046 M-circle dot, and M-2 sin(3) i = 0.504 +/- 0.032 M-circle dot.Öğe Optimization applied to selected exoplanets(Springer, 2021) Ng, Shi Yuan; Jiadi, Zhou; Püsküllü, Çağlar; Banks, Timothy; Budding, Edwin; Rhodes, Michael D.Transit and radial velocity models were applied to archival data in order to examine exoplanet properties, in particular for the recently discovered super-Earth GJ357b. There is however considerable variation in estimated model parameters across the literature, and especially their uncertainty estimates. This applies even for relatively uncomplicated systems and basic parameters. Some published accuracy values thus appear highly overoptimistic. We present our reanalyses with these variations in mind and specify parameters with appropriate confidence intervals for the exoplanets Kepler-1b, -2b, -8b, -12b, -13b, -14b, -15b, -40b and -77b and 51 Peg. More sophisticated models in WINFITTER (WF), EXOFAST and DACE were applied, leading to mean planet densities for Kepler-12b, -14b, -15b and -40b as: 0:11 0:01, 4:04 0:58, 0:43 0:05 and 1:19þ0:31 0:36 g per cc respectively. We confirm a rocky mean density for the Earth-like GJ357b, although we urge caution about the modelling given the low S/N data. We cannot confidently specify parameters for the other two proposed planets in this system.Öğe Phenomenological gravity and eclipses(Astronomical Soc Pacific, 2007) Budding, EdwinA phenomenological approach to material inertia and gravity allows a direct explanation of observed effects. While the high-energy implications are perplexing, eclipses, of various forms, allow practical tests to be made. LAGEOS satellite anomalies may provide relevant evidence. But other possible, eclipse-related, data avenues may allow better numerical evaluations of the Laplace absorption parameter (h). A brief review is presented.Öğe Solar and stellar eclipse mapping(Astronomical Soc Pacific, 2007) Budding, EdwinThe special circumstance of solar eclipse affords an opportunity to review its background, particularly in the cultural context of western Anatolia. This links with a current project of Canakkale Onsekiz Mart University. Turning to the more general subject of stellar eclipses, topics of particular note concern: choice of fitting functions, disk eclipses, spot eclipses and the gravity-darkening effect. These topics arise within new era eclipsing binary studies and are relevant to active researches on remote binaries and extrasolar planets.Öğe Spectroscopic Study of the Early-Type Binary HX Vel A(Cambridge Univ Press, 2012) Ozkardes, Burcu; Surgit, Derya; Erdem, Ahmet; Budding, Edwin; Soydugan, Faruk; Demircan, OsmanThis paper presents high resolution spectroscopy of the HX Vel (IDS 08390-4744 AB) multiple system. New spectroscopic observations of the system were made at Mt. John University Observatory in 2007 and 2008. Radial velocities of both components of HX Vel A were measured using gaussian fitting. The spectroscopic mass ratio of the close binary was determined as 0.599 +/- 0.052, according to a Keplerian orbital solution. The resulting orbital elements are a(1)sini=0.0098 +/- 0.0003 AU, a(2)sini=0.0164 +/- 0.0003 AU, M(1)sin(3)i=1.19 +/- 0.07 M-circle dot and M(2)sin(3)i=0.71 +/- 0.04 M-circle dot.Öğe Standard UBV observations at the Çanakkale University Observatory (ÇUO)(2005) Bakiş, Hicran; Bakiş, Volkan; Demircan, Osman; Budding, EdwinBy using standard and comparison star observations carried out at different times of the year, at Çanakkale Onsekiz Mart University Observatory, we obtained the atmospheric extinction coefficients at the observatory. We also obtained transformation coefficients and zero-point constants for the transformation to the standard Johnson UBV system, of observations in the local system carried out with the SSP5A photometer and T40 telescope. The transmission curves and the mean wavelengths of the UBV filters as measured in the laboratory appear not much different from those of the standard Johnson system and found inside the transmission curve of the standard mean atmosphere. © TÜBİTAK.Öğe Standard UBV Observations at the Canakkale University Observatory (CUO)(Tubitak Scientific & Technological Research Council Turkey, 2005) Bakis, Hicran; Bakis, Volkan; Demircan, Osman; Budding, EdwinBy using standard and comparison star observations carried out at different times of the year, at Canakkale Onsekiz Mart University Observatory, we obtained the atmospheric extinction coefficients at the observatory. We also obtained transformation coefficients and zero-point constants for the transformation to the standard Johnson UBV system, of observations in the local system carried out with the SSP5A photometer and T40 telescope. The transmission curves and the mean wavelengths of the UBV filters as measured in the laboratory appear not much different from those of the standard Johnson system and found inside the transmission curve of the standard mean atmosphere.Öğe Zdenek Kopal: Astronomer and Teacher(Astronomical Soc Pacific, 2015) Budding, EdwinThough the title points to a wider program than can be accommodated in one individual paper, the meeting was called with such considerations as a background. This paper then raises primarily questions that people might ask in connection with Zdenek Kopal and his work, rather than giving comprehensive answers. A few general thinking points are presented first, followed by a selection of particular illustrations arranged by the several decades over which Kopal was active in astronomical science. A concluding section returns to some general and personal reflections.
