Comprehensive spectroscopic and photometric study of pulsating eclipsing binary star AI Hya (original) (raw)
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Communications in Asteroseismology, 2010
CCD observations of 24 eclipsing binary systems with spectral types ranging between A0-F0, candidate for containing pulsating components, were obtained. Appropriate exposure times in one or more photometric filters were used so that short-periodic pulsations could be detected. Their light curves were analyzed using the Period04 software in order to search for pulsational behaviour. Two new variable stars, namely GSC 2673-1583 and GSC 3641-0359, were discovered as by-product during the observations of eclipsing variables. The Fourier analysis of the observations of each star, the dominant pulsation frequencies and the derived frequency spectra are also presented.
A simultaneous spectroscopic and photometric study of two eclipsing binaries: V566 Oph and V972 Her
Astrophysics and Space Science, 2018
In this study, we have performed simultaneous solutions of light and radial velocity curves of two eclipsing binary systems, V566 Oph and V972 Her. We observed both systems spectroscopically with a very recently installed spectrograph on the 40 cm telescope, T40, located in Ankara University Kreiken Observatory (AUKR), for the first time. We made use of the photometric data from the Hipparcos satellite for V972 Her, while we obtained the photometric observations of V566 Oph by using the 35 cm telescope, T35, located also in our observatory campus. We derived the absolute parameters for both systems and discussed their evolutionary states. In addition to the simultaneous analysis, we have also analyzed the change in mid-eclipse times for V566 Oph, and found cyclic variations, for which we have discussed light-time effect and magnetic activity as their potential origin, superimposed on a secular change due to a mass transfer between the components of the binary.
Astronomy & Astrophysics, 2014
Context. Rapid advancements in light-curve and radial-velocity curve modelling, as well as improvements in the accuracy of observations, allow more stringent tests of the theory of stellar evolution. Binaries with rapid apsidal advance are particularly useful in this respect since the internal structure of the stars can also be tested. Aims. Thanks to its long and rich observational history and rapid apsidal motion, the massive eclipsing binary Y Cyg represents one of the cornerstones of critical tests of stellar evolutionary theory for massive stars. Nevertheless, the determination of the basic physical properties is less accurate than it could be given the existing number of spectral and photometric observations. Our goal is to analyse all these data simultaneously with the new dedicated series of our own spectral and photometric observations from observatories widely separated in longitude. Methods. We obtained new series of UBV observations at three observatories separated in local time to obtain complete light curves of Y Cyg for its orbital period close to 3 days. This new photometry was reduced and carefully transformed to the standard UBV system using the HEC22 program. We also obtained new series of red spectra secured at two observatories and re-analysed earlier obtained blue electronic spectra. Reduction of the new spectra was carried out in the IRAF and SPEFO programs. Orbital elements were derived independently with the FOTEL and PHOEBE programs and via disentangling with the program KOREL. The final combined solution was obtained with the program PHOEBE . Results. Our analyses provide the most accurate value of the apsidal period of (47.805±0.030) yrs published so far and the following physical elements: M1 = 17.72 ± 0.35 M⊙, M2 = 17.73 ± 0.30 M⊙, R1 = 5.785 ± 0.091 R⊙, and R2 = 5.816 ± 0.063 R⊙. The disentangling thus resulted in the masses, which are somewhat higher than all previous determinations and virtually the same for both stars, while the light curve implies a slighly higher radius and luminosity for star 2. The above empirical values imply the logarithm of the internal structure constant log k2 = −1.937. A comparison with Claret's stellar interior models implies an age close to 2 × 10 6 yrs for both stars. Conclusions. The claimed accuracy of modern element determination of 1-2 per cent still seems a bit too optimistic and obtaining new high-dispersion and high-resolution spectra is desirable.
Photometric Study of Three Short-Period Eclipsing Binaries from the ASAS Catalogue
International Journal of Astronomy and Astrophysics, 2013
We present the results of our study of three previously unstudied short-period eclipsing binaries, namely: ASAS 110609 − 2045.3, ASAS105331 − 7424.7, and ASAS 130057 + 2120.3. Using the visual (V)-band data obtained from the ASAS catalogue, the orbital and physical parameters of the systems were derived for the first time using the Wilson-Divenney (WD) codes. Our investigation revealed that ASAS 110609 − 2045.3 is a near-contact binary star of the W Uma type having an angle of inclination of 80˚ ± 1, a mass ratio of about 0.5, an orbital period of 0.2933 ± 0.0130 days, and an effective temperature in the range of 5800 K-6200 K, making it a G2V-F7V spectral system. ASAS 105331 − 7424.7 was established to be an over-contact binary system of the W Uma type, inclined at 86˚ ± 2 to the line of sight, having a mass ratio of about 0.9, a period of 0.4825 ± 0.0002, and an effective temperature in the range of 5200 K-5300 K, making it a K2V-K0V spectral system. A third light factor of just 0.1 was established for the system, however, no evidence of starspots or discs was inferred for either component. ASAS 130,057 + 2120.3 is a W Uma binary having a mass ratio of about 0.6 in a state of marginal contact. Its orbital inclination is 55˚ ± 1; the effective temperature is in the range of 6200 K-6500 K, making it a F7V-F5V stellar system. The system showed evidence of third light, with a third light factor of 0.6, however, the presence of spots or discs could not be established for either component. The deduced period was 0.8930 ± 0.0014 days. None of the systems showed any evidence of the O'Connell effect on either component.
Orbital and physical parameters of eclipsing binaries from the All-Sky Automated Survey catalogue
Astronomy & Astrophysics, 2011
Aims. We present the results of our detailed spectroscopic and photometric analysis of two previously unknown <1 M detached eclipsing binaries: ASAS J045304-0700.4 and ASAS J082552-1622.8. Methods. With the HIgh Resolution Echelle Spectrometer (HIRES) on the Keck-I telescope, we obtained spectra of both objects covering large fractions of orbits of the systems. We also obtained V and I band photometry with the 1.0-m Elizabeth telescope of the South African Astronomical Observatory (SAAO). The orbital and physical parameters of the systems were derived with the PHOEBE and JKTEBOP codes. We investigated the evolutionary status of both binaries with several sets of widely-used isochrones. Results. Our modelling indicates that (1) ASAS J045304-0700.4 is an old, metal-poor, active system with component masses of M 1 = 0.8338 ± 0.0036 M , M 2 = 0.8280 ± 0.0040 M and radii of R 1 = 0.848 ± 0.005 R and R 2 = 0.833 ± 0.005 R , which places it at the end of the Main Sequence evolution-a stage rarely observed for this type of stars. (2) ASAS J082552-1622.8 is a metal-rich, active binary with component masses of M 1 = 0.7029 ± 0.0045 M , M 2 = 0.6872 ± 0.0049 M and radii of R 1 = 0.694 +0.007 −0.011 R and R 2 = 0.699 +0.011 −0.014 R. Both systems show significant out-of-eclipse variations, probably owing to large, cold spots. We also investigated the influence of a third light in the second system.
Astronomische Nachrichten, 2010
We present a preliminary spectroscopic analysis of the binary system V577Oph, observed during the summer of 2007 on the 2.6 m NOT telescope on La Palma. We have obtained time series spectroscopic observations, which show clear binary motion as well as radial velocity variations due to pulsation in the primary star. By modelling the radial velocities we determine a full orbital solution of the system, which yields MA sin3 i = 1.562 ± 0.012 M⊙ and MB sin3 i = 1.461 ± 0.020 M⊙. An estimate of inclination from photometry yields a primary mass of ∼1.6 M⊙. Using this derived mass, and the known pulsation frequency we can impose a lower limit of 1 Gyr on the age of the system, and constrain the parameters of the oscillation mode. We show that with further analysis of the spectra (extracting the atmospheric parameters), tighter constraints could be imposed on the age, metallicity and the mode parameters. This work emphasizes the power that a single pulsation frequency can have for constrain...
New photometric solutions have been carried out on the important eccentric eclipsing system V380 Cygni (B1.5 II-III + B2 V) from U BV differential photoelectric photometry obtained by us. The photometric elements obtained from the analysis of the light curves have been combined with the spectroscopic solution recently published by Popper & Guinan and have led to the physical properties of the system components. The effective temperature of the stars has been determined by fitting IUE UV spectrophotometry to Kurucz model atmospheres and compared with other determinations from broad-band and intermediate-band standard photometry. The values of mass, absolute radius, and effective temperature, for the primary and secondary stars are: 11.1±0.5 M ⊙ , 14.7±0.2 R ⊙ , 21 350±400 K, and 6.95±0.25 M ⊙ , 3.74±0.07 R ⊙ , 20 500±500 K, respectively. In addition, a re-determination of the system's apsidal motion rate has been done from the analysis of 12 eclipse timings obtained from 1923 to 1995. The apsidal motion study yields the internal mass distribution of the more luminous component. Using stellar structure and evolutionary models with modern input physics, tests on the extent of convection in the core of the more massive B1.5 II-III star of the system have been carried out. Both the analysis of the log g − log T eff diagram and the apsidal motion study indicate a star with a larger convective core, and thus more centrally condensed, than currently assumed. This has been quantified in form of an overshooting parameter with a value of α ov ≈ 0.6 ± 0.1. Finally, the tidal evolution of the system (synchronization and circularization times) has also been studied.
Physical Properties of Eclipsing Binaries from Photometric Data - Senior Honours Project
The study of eclipsing binary stars is a key area of interest in astrophysics, that helps determining a multitude of astronomical properties, from stellar evolution to stellar classification to the relative locations of astronomical objects and the structure of the galaxy itself. This project utilises photometric data in the near-Infrared spectrum to describe a method of determing properties such as Temperature, distances and stellar classification from photometric data. Due to the limitations of infrared data, the results for the stellar type distribution and properties were different from what was expected. A more extensive study with optical data would be able to utilise the method to determine various properties of stars in eclipsing binary systems with a higher degree of accuracy. Declaration I declare that this project and report is my own work.
Monthly Notices of the Royal Astronomical Society, 2021
We present results of the analysis of light and radial velocity (RV) curves of eight detached eclipsing binaries observed by the All-Sky Automated Survey, which we have followed up with high-resolution spectroscopy, and were later observed by the Keplersatellite as part of the K2mission. The RV measurements came from spectra obtained with OAO-188/HIDES, MPG-2.2 m/FEROS, SMARTS 1.5 m/CHIRON, Euler/CORALIE, ESO-3.6 m/HARPS, and OHP-1.93/ELODIE instruments. The K2 time-series photometry was analysed with the jktebop code, with out-of-eclipse modulations of different origin taken into account. Individual component spectra were retrieved with the fd3 code, and analysed with the code ispec in order to determine effective temperatures and metallicities. Absolute values of masses, radii, and other stellar parameters are calculated, as well as ages, found through isochrone fitting. For five systems, such analysis has been done for the first time. The presented sample consists of a variety of...