Elemental abundance analyses with DAO spectrograms: XXXI. The early F supergiants <i>ν</i> Her (F2 II) and 41 Cyg (F5 Ib‐II)

Adelman, Saul J.; Çay, İpek H.; Tektunali, H. G.; Gulliver, A. F.; Akadam-Teker, Başak

doi:10.1002/asna.200710863

Cited by 3 publications

(1 citation statement)

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“…The process depended on the rate of star formation in various regions of the Galaxy, as well as on the interstellar gas density. [3]…”

Section: Introductionmentioning

confidence: 99%

Composition of Atmospheres of Normal and Peculiar stars

Alhawi¹,

Mazyed²

2019

International Advanced Research Journal in Science, Engineering

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Context. The study of the chemical composition of stellar atmospheres is the main and most valuable source of information to determine the fundamental characteristics of stellar atmospheres, in one hand, and to studying the evolution of matter in the interior of stars, in the interstellar medium, and matter of the Galaxy, on the other hand. Aims. This study is to confirm that the effects of gravitational diffusion and light pressure begin to work, starting from specific degree of temperatures atmospheres of the main succession stars. Methods. Within the framework of this study, we processed Echelle spectra of the star "99Her" which have a spectral classes A-F, obtained with a 1.5-meter telescope PTT-150. In the investigation in question strengths of large numbers of absorption lines in stellar spectra were determined through photographic photometry of high resolution spectra, and the line strengths were than evaluated and converted into relative abundances on the basis of theoretical calculations of physical properties of model stellar atmospheres. Results. We determined the fundamental parameters of atmospheres:-the effective temperature, the acceleration of gravity, the micro-turbulent velocity. We also calculated the content of the chemical elements.

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“…The process depended on the rate of star formation in various regions of the Galaxy, as well as on the interstellar gas density. [3]…”

Section: Introductionmentioning

confidence: 99%

Composition of Atmospheres of Normal and Peculiar stars

Alhawi¹,

Mazyed²

2019

International Advanced Research Journal in Science, Engineering

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Carbon and Oxygen Abundances Across the Hertzsprung Gap

Adamczak

Lambert

2014

ApJ

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We derived atmospheric parameters and spectroscopic abundances for C and O for a large sample of stars located in the Hertzsprung gap in the Hertzsprung-Russell diagram in order to detect chemical peculiarities and get a comprehensive overview of the population of stars in this evolutionary state. We have observed and analyzed high-resolution spectra (R = 60,000) of 188 stars in the mass range 2-5 M with the 2.7 m Harlan J. Smith Telescope at the McDonald Observatory including 28 stars previously identified as Am/Ap stars. We find that the C and O abundances of the majority of stars in the Hertzsprung gap are in accordance with abundances derived for local lower-mass dwarfs but detect expected peculiarities for the Am/Ap stars. The C and O abundances of stars with T eff < 6500 K are slightly lower than for the hotter objects but the C/O ratio is constant in the analyzed temperature domain. No indication of an alteration of the C and O abundances of the stars by mixing during the evolution across the Hertzsprung gap could be found before the homogenization of their atmospheres by the first dredge-up.

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Determined the Effective Temperature and Gravity Acceleration at the Atmosphere of (HD165908) Star

Alhawi

Mazyed

2021

IOP Conf. Ser.: Mater. Sci. Eng.

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The study of the chemical composition of stars in our Galaxy showed that it changes in a non-random way from a star to a star: older stars and halo stars have a metal deficit compared to young stars and disc stars. However, this is not always the case. Sometimes old stars have a solar chemical composition, and young stars show a deficit of metals. It is believed that the formed stars has a chemical composition of the interstellar substance from which it was formed; therefore, the initial content of elements in its atmosphere depends on the time and place of birth. Within the framework of this work, echelle spectra of star 99Her of spectral classes A-F has been proceed, obtained with a 1.5-meter telescope PTT-150 (Russian Turkish Telescope-150). As a result of processing the spectra, the equivalent widths of unbend and weakly blended absorption lines were measured, 350 lines this star. The measured equivalent line widths can be used for other studies of the atmospheres of the A-F stars composition. Stars with temperatures of 8000-9000 K show a significant excess of elements heavier than iron and some deficiency of light elements. These results, apparently, are a consequence of the effects of light pressure and gravitational diffusion of atoms and ions in atmospheres of calm and radiative atmospheres of A-stars.

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Elemental abundance analyses with DAO spectrograms: XXXI. The early F supergiants ν Her (F2 II) and 41 Cyg (F5 Ib‐II)

Cited by 3 publications

References 34 publications

Composition of Atmospheres of Normal and Peculiar stars

Composition of Atmospheres of Normal and Peculiar stars

Carbon and Oxygen Abundances Across the Hertzsprung Gap

Determined the Effective Temperature and Gravity Acceleration at the Atmosphere of (HD165908) Star

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