Yazar "Basturk, O." seçeneğine göre listele

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    Abundance analysis of the supergiant stars HD 80057 and HD 80404 based on their UVES Spectra
    (ELSEVIER SCIENCE BV, 2016) Tanriverdi, T.; Basturk, O.
    This study presents elemental abundances of the early A-type supergiant HD 80057 and the late A type supergiant HD 80404. High resolution and high signal-to-noise ratio spectra published by the UVES Paranal Observatory Project (Bagnulo et al., 2003)(1) were analyzed to compute their elemental abundances using ATLAS9 (Kurucz, 1993; 2005; Sbordone et al., 2004). In our analysis we assumed local thermodynamic equilibrium. The atmospheric parameters of HD 80057 used in this study are from Firnstein and Przybilla (2012), and that of HD 80404 are derived from spectral energy distribution, ionization equilibria of Cr and Fe I/II, the fits to the wings of Balmer and Paschen lines as T-eff = 7700 +/- 150 K and log g = 1.60 +/- 0.15 (in cgs). The microturbulent velocities of HD 80057 and HD 80404 have been determined as 4.3 +/- 0.1 and 2.2 +/- 0.0 km s(-1), respectively. The rotational velocities are 15 +/- 1 and 7 +/- 2 km s(-1) and their macroturbulence velocities are 24 +/- 2 and 2 +/- 1 km s(-1). We have given the abundances of 25 ions of 19 elements for HD 80057 and 36 ions of 25 elements for HD 80404. The abundances are close to solar values, except for some elements (Na, Sc, Ti, V, Ba, and Sr). We have found the metallicities [M/H] for HD 80057 and HD 80404 as -0.16 +/- 0.24 and -0.04 +/- 0.16 dex, respectively. The evolutionary status of these stars are discussed and their nitrogen-to-carbon (N/C) and nitrogen-to oxygen (N/O) ratios show that they are in their blue supergiant phase before the red supergiant region. (C) 2016 Elsevier B.V. All rights reserved.
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    PHOTOMETRIC ANALYSIS OF HS Aqr, EG Cep, VW LMi, AND DU Boo
    (IOP PUBLISHING LTD, 2013) Djurasevic, G.; Basturk, O.; Latkovic, O.; Yilmaz, M.; Caliskan, S.; Tanriverdi, T.; Ekmekci, F.
    We analyze new multicolor light curves for four close late-type binaries: HS Aqr, EG Cep, VW LMi, and DU Boo, in order to determine the orbital and physical parameters of the systems and estimate the distances. The analysis is done using the modeling code of G. Djurasevic, and is based on up-to-date measurements of spectroscopic elements. All four systems have complex, asymmetric light curves that we model by including bright or dark spots on one or both components. Our findings indicate that HS Aqr and EG Cep are in semi-detached, while VW LMi and DU Boo are in overcontact configurations.
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    Physical parameters of some close binaries: ET Boo, V1123 Tau, V1191 Cyg, V1073 Cyg and V357 Peg
    (ELSEVIER SCIENCE BV, 2012) Ekmekci, F.; Elmasli, A.; Yilmaz, M.; Kilicoglu, T.; Tanriverdi, T.; Basturk, O.; Selam, S. O.
    With the aim of providing new and up-to-date absolute parameters of some close binary systems, new BVR CCD photometry was carried out at the Ankara University Observatory (AUG) for five eclipsing binaries, ET Boo, V1123 Tau, V1191 Cyg, V1073 Cyg and V357 Peg between April, 2007 and October, 2008. In this paper, we present the orbital solutions for these systems obtained by simultaneous light and radial velocity curve analyses. Extensive orbital solution and absolute parameters for ET Boo system were given for the first time through this study. According to the analyses, ET Boo is a detached binary while the parameters of four remaining systems are consistent with the nature of contact binaries. The evolutionary status of the components of these systems are also discussed by referring to their absolute parameters found in this study. (C) 2012 Elsevier B.V. All rights reserved.