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Öğe Basic physical properties of the close binary V497 Cep in the open cluster NGC 7160(EDP Sciences, 2003) Yakut K.; Tarasov A.E.; Ibanoglu C.; Harmanec P.; Kalomeni B.; Holmgren D.E.; Bozic H.; Eenens P.New light and radial-velocity curves of V497 Cep, a binary in the open cluster NGC 7160, were obtained and the linear ephemeris of the system was refined to HJD (MinI) = (2446299.1596±0.0064) + (1d.2028287 ± 0d.0000015) × E. The first light and radia-velocity curve solutions allowed us to derive the basic physical properties of this astrophysically important binary. It was found that the observed light variation of V497 Cep consists of a strong ellipticity effect and a small contribution from grazing eclipses. A comparison of masses and radii of V497 Cep with theoretical evolutionary tracks indicates that both binary components are very close to the zero-age main sequence. A comparison of disentangled line profiles of the He I 6678 line with synthetic, rotationally broadened line profiles indicates that the rotation of both stars is synchronized with the orbital revolution as expected. This finding increases the credibility of our solutions. We find E(B - V) = 0.m39. The distance to the cluster NGC 7160 was found to be about 760 (±100) pc which agrees will with other available estimates.Öğe Improved model of the triple system V746 Cassiopeiae that has a bipolar magnetic field associated with the tertiary(EDP Sciences, 2018) Harmanec P.; Broz M.; Mayer P.; Zasche P.; Kotková L.; Nemravová J.A.; Dukes R.J.; Korcáková D.; Šlechta M.; Kran E.; Krícek R.; Juryšek J.V746 Cas is known to be a triple system composed of a close binary with an alternatively reported period of either 25d:4 or 27d:8 and a distant third component in a 170 yr (62 000 d) orbit. The object was also reported to exhibit multiperiodic light variations with periods from 0d: 83 to 2d: 50, on the basis of which it was classified as a slowly pulsating B star. Interest in further investigation of this system was raised by the recent detection of a variable magnetic field. Analysing spectra from four instruments, earlier published radial velocities, and several sets of photometric observations, we arrived at the following conclusions: (1) The optical spectrum is dominated by the lines of the B-type primary (Teff 1 16 500(100)K), contributing 70% of the light in the optical region, and a slightly cooler B tertiary (Teff 3 13 620(150)K). The lines of the low-mass secondary are below our detection threshold; we estimate that it could be a normal A or F star. (2) We resolved the ambiguity in the value of the inner binary period and arrived at a linear ephemeris of Tsuper: conj: = HJD 2 443 838:78(81) + 25d:41569(42) × E. (3) The intensity of the magnetic field undergoes a sinusoidal variation in phase with one of the known photometric periods, namely 2d:503867(19), which we identify with the rotational period of the tertiary. (4) The second dominant photometric 1d: 0649524(40) period is tentatively identified with the rotational period of the broad-lined B-type primary, but this interpretation is much less certain and needs further verification. (5) If our interpretation of photometric periods is confirmed, the classification of the object as a slowly pulsating B star should be revised. (6) Applying an N-body model to different types of available observational data, we can constrain the orbital inclination of the inner orbit to 60° < i1 < 85° even in the absence of binary eclipses, and we estimate the probable properties of the triple system and its components.Öğe The orbital elements and physical properties of the eclipsing binary BD+36° 3317, a probable member of ? Lyrae cluster(EDP Sciences, 2016) Kiran E.; Harmanec P.; De?irmenci Ö.L.; Wolf M.; Nemravová J.; Šlechta M.; Koubsky P.Context. The fact that eclipsing binaries belong to a stellar group is useful, because the former can be used to estimate distance and additional properties of the latter, and vice versa. Aims. Our goal is to analyse new spectroscopic observations of BD+ 36°3317 along with the photometric observations from the literature and, for the first time, to derive all basic physical properties of this binary. We aim to find out whether the binary is indeed a member of the ? Lyr open cluster. Methods. The spectra were reduced using the IRAF program and the radial velocities were measured with the program SPEFO. The line spectra of both components were disentangled with the program KOREL and compared to a grid of synthetic spectra. The final combined radial-velocity and photometric solution was obtained with the program PHOEBE. Results. We obtained the following physical elements of BD+36°3317: M1 = 2.24 ± 0.07 M?, M2 = 1.52 ± 0.03 M?, R1 = 1.76 ± 0.01 R?, R2 = 1.46 ± 0.01 R?, log L1 = 1.52 ± 0.08 L?, log L2 = 0.81 ± 0.07 L?. We derived the effective temperatures Teff,1 = 10 450 ± 420 K, Teff,2 = 7623 ± 328 K. Both components are located close to zero age main sequence in the Hertzsprung-Russell (HR) diagram and their masses and radii are consistent with the predictions of stellar evolutionary models. Our results imply the average distance to the system d¯ = 330 ± 29 pc. We re-investigated the membership of BD+36°3317 in the ? Lyr cluster and confirmed it. The distance to BD+36°3317, given above, therefore represents an accurate estimate of the true distance for ? Lyr cluster. Conclusions. The reality of the ? Lyr cluster and the cluster membership of BD+36°3317 have been reinforced. © ESO, 2016.
