Physics / Fizik

Permanent URI for this collectionhttps://hdl.handle.net/11147/6

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  • Article
    Citation - WoS: 12
    Citation - Scopus: 12
    Short and Long Time-Scale Variability in Magnetic Cataclysmic Variables: Long-Term Monitoring of Polars
    (Oxford University Press, 2012) Kalomeni, Belinda
    We present long-term observations of the magnetic cataclysmic variables AM Her, AN UMa, AR UMa, DP Leo and V1309 Ori. Analyses of both short- and long-period light variations are presented. For the first time, as far as we know, long-period variations of AN UMa and AR UMa have been studied and multiple frequencies obtained. Fourier analysis indicates 170-, 218- and 180-d variations for AM Her, AN UMa and AR UMa, respectively. These periodicities may be due to modulation of the mass-transfer rate resulting from magnetic cycles in the secondary stars. In addition, we collect the physical parameters of polars from the literature and estimate their mass-transfer rates and orbital period variation and give a rough estimation of the donor magnetic fields.
  • Article
    Citation - WoS: 8
    Citation - Scopus: 7
    Mode Identification in the High-Amplitude {\delta} Scuti Star V2367 Cyg
    (Oxford University Press, 2013) Ulusoy, Ceren; Gülmez, T.; Stateva, I.; Dimitrov, D.; Iliev, I. Kh.; Kobulnicky, H. A.; Yaşarsoy, B.; Alvarez, M.; Michel, R.; Fox Machado, L.; Damasso, M.; Carbognani, A.; Cenadelli, D.; Pickering, T. E.; Kwon, J.; Tamura, M.; Balona, L. A.
    We report on a multisite photometric campaign on the high-amplitude delta Scuti star V2367 Cyg in order to determine the pulsation modes. We also used high-dispersion spectroscopy to estimate the stellar parameters and projected rotational velocity. Time series multicolour photometry was obtained during a 98-d interval from five different sites. These data were used together with model atmospheres and non-adiabatic pulsation models to identify the spherical harmonic degree of the three independent frequencies of highest amplitude as well as the first two harmonics of the dominant mode. This was accomplished by matching the observed relative light amplitudes and phases in different wavebands with those computed by the models. In general, our results support the assumed mode identifications in a previous analysis of Kepler data. © 2012 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.
  • Article
    Citation - WoS: 28
    Citation - Scopus: 28
    Basic Physical Properties of the Low-Temperature Contact Binary System V781 Tau and the Near-Contact Binary System V836 Cyg
    (Oxford University Press, 2005) Yakut, Kadri; Ulaş, Burak; Kalomeni, Belinda; Gülmen, Ömür
    We present a detailed photometric study of the low-temperature contact binary V781 Tau, and the near-contact binary V836 Cyg. We have combined the parameters obtained from the light-curve analysis with those found by the spectral studies and we have determined the orbital and physical parameters of the stars. We have collected the times of the mid-eclipses obtained so far and combined with the times obtained in this study. By analysing all these data we determined the mass transfer rate from the massive star to the less massive one for V781 Tau, and from the less massive component to the massive one in the case of V836 Cyg. Finally, we have compared the results obtained for V781 Tau and for V836 Cyg with similar systems.