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

Abstract

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.