taner tanrıverdi | Niğde Ömer Halisdemir Üniversitesi / Nigde Omer Halisdemir University (original) (raw)

Papers by taner tanrıverdi

Proceedings of the International Astronomical Union, 2004

In this study we use preliminary atmospheric parameters for the A0 Ib supergiant η Leo (T eff , l... more In this study we use preliminary atmospheric parameters for the A0 Ib supergiant η Leo (T eff , log g and microturbulent velocity) to provide initial estimates of the elemental abundances from S ii, Ti ii, Cr ii, Fe i and Fe ii lines by using spectrograms with a two pixel resolution of 0.072Å and signal-to-noise ratio 200 taken at the Dominion Astrophysical Observatory.

New Astronomy, 2016

This study presents elemental abundances of the early A-type supergiant HD 80057 and the late A-t... more 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 analysed 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 & Przybilla (2012), and that of HD 80404 are derived from spectral energy distribution, ionization equilibria of Cr i/ii and Fe i/ii, and the fits to the wings of Balmer lines 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 ± 0.7 km s −1. 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 27 ions of 20 elements for HD 80057 and 39 ions of 25 elements for HD 80404. The abundances are close to solar values, except for some elements (Na,

The Astronomical Journal, 2013

ABSTRACT We analyze new multicolor light curves for four close late-type binaries: HS Aqr, EG Cep... more ABSTRACT 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. Djurašević, 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.

New Astronomy, 2013

This study aims to analyse the elemental abundances for the late B type supergiant star σ Cyg and... more This study aims to analyse the elemental abundances for the late B type supergiant star σ Cyg and the early A-type supergiant η Leo using ATLAS9 (Kurucz, 1995; Sbordone et al., 2004), assuming local thermodynamic equilibrium (LTE). The spectra used in this study are obtained from Dominion Astrophysical Observatory and have high resolution and signal-to-noise ratios. The effective temperature and the surface gravity of σ Cyg are determined from the

Proceedings of the International Astronomical Union, 2004

In this study we use preliminary atmospheric parameters for the A0 Ib supergiant η Leo (T eff , l... more In this study we use preliminary atmospheric parameters for the A0 Ib supergiant η Leo (T eff , log g and microturbulent velocity) to provide initial estimates of the elemental abundances from S ii, Ti ii, Cr ii, Fe i and Fe ii lines by using spectrograms with a two pixel resolution of 0.072Å and signal-to-noise ratio 200 taken at the Dominion Astrophysical Observatory.

New Astronomy, 2016

This study presents elemental abundances of the early A-type supergiant HD 80057 and the late A-t... more 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 analysed 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 & Przybilla (2012), and that of HD 80404 are derived from spectral energy distribution, ionization equilibria of Cr i/ii and Fe i/ii, and the fits to the wings of Balmer lines 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 ± 0.7 km s −1. 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 27 ions of 20 elements for HD 80057 and 39 ions of 25 elements for HD 80404. The abundances are close to solar values, except for some elements (Na,

The Astronomical Journal, 2013

ABSTRACT We analyze new multicolor light curves for four close late-type binaries: HS Aqr, EG Cep... more ABSTRACT 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. Djurašević, 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.

New Astronomy, 2013

This study aims to analyse the elemental abundances for the late B type supergiant star σ Cyg and... more This study aims to analyse the elemental abundances for the late B type supergiant star σ Cyg and the early A-type supergiant η Leo using ATLAS9 (Kurucz, 1995; Sbordone et al., 2004), assuming local thermodynamic equilibrium (LTE). The spectra used in this study are obtained from Dominion Astrophysical Observatory and have high resolution and signal-to-noise ratios. The effective temperature and the surface gravity of σ Cyg are determined from the