Yazar "Smalley, B." seçeneğine göre listele

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    Öğe
    Eclipsing binary stars with a ? Scuti component
    (Oxford Univ Press, 2017) Alicavus, F. Kahraman; Soydugan, Esin; Smalley, B.; Kubat, J.
    Eclipsing binaries with a delta Sct component are powerful tools to derive the fundamental parameters and probe the internal structure of stars. In this study, spectral analysis of six primary delta Sct components in eclipsing binaries has been performed. Values of T-eff, v sin i, and metallicity for the stars have been derived from medium-resolution spectroscopy. Additionally, a revised list of delta Sct stars in eclipsing binaries is presented. In this list, we have only given the d Sct stars in eclipsing binaries to show the effects of the secondary components and tidallocking on the pulsations of primary delta Sct components. The stellar pulsation, atmospheric and fundamental parameters (e.g. mass, radius) of 92 d Sct stars in eclipsing binaries have been gathered. Comparison of the properties of single and eclipsing binary member delta Sct stars has been made. We find that single d Sct stars pulsate in longer periods and with higher amplitudes than the primary delta Sct components in eclipsing binaries. The v sin i of delta Sct components is found to be significantly lower than that of single delta Sct stars. Relationships between the pulsation periods, amplitudes and stellar parameters in our list have been examined. Significant correlations between the pulsation periods and the orbital periods, Teff, logg, radius, mass ratio, v sin i and the filling factor have been found.
  • [ X ]
    Öğe
    Spectroscopy of hot ? Doradus and A-F hybrid Kepler candidates close to the hot border of the ? Scuti instability strip
    (Oxford Univ Press, 2020) Alicavus, F. Kahraman; Poretti, E.; Catanzaro, G.; Smalley, B.; Niemczura, E.; Rainer, M.; Handler, G.
    If gamma Dor-type pulsations are driven by the convective blocking mechanism, a convective envelope at a sufficient depth is essential. There are several hot gamma Dor and hybrid star candidates in which there should not be an adequate convective envelope to excite the gamma Dor-type oscillations. The existence of these hot objects needs an explanation. Therefore, we selected, observed, and studied 24 hot gamma Dor and hybrid candidates to investigate their properties. The atmospheric parameters, chemical abundances, and vsin i values of the candidates were obtained using medium-resolution (R = 46 000) spectra taken with the Fibre-fed Echelle Spectrograph instrument mounted at the Nordic Optical Telescope. We also carried out frequency analyses of the Kepler long- and short-cadence data to determine the exact pulsation contents. We found only five bona fide hot gamma Dor and three bona fide hot hybrid stars in our sample. The other 16 stars were found to be normal gamma Dor, delta Sct, or hybrid variables. No chemical peculiarity was detected in the spectra of the bona fide hot gamma Dor and hybrid stars. We investigated the interplay between rotation and pulsational modes. We also found that the hot gamma Dor stars have higher Gaia luminosities and larger radii compared to main-sequence A-F stars.