DETERMINATION OF THE FUNDAMENTAL PARAMETERS OF THE GIANT CLASSES F AND G HR8718 (F5II), HR8304(G8II), HR8179(G5II), HR8778 (G8IV)

Abstract

The atmospheres of giants of the F and G HR8718 (F5II), HR8304(G8II), HR8179(G5II), HR8778 (G8IV) are investigated. Having compared the observed and theoretical value of the photometric indices β, [c1], Q and resing the parallax method, the effective temperatures and the surface gravity of the stars are determined. The following values of the effective temperature and surface
gravity Tef f = 6800 ± 100K, logg=4.0±0.1(HR8718); Tef f = 5010 ± 100K, logg=2.1±0.1(HR8304); Tef f = 5200 ± 150K, logg=2.7±0.2 (HR8179); Tef f = 5300 ± 100 K, logg=3.2± 0.1(HR8778).
The parameter (velocity) of microturbulence was investigated along the lines of Fe(II). It is found that, ξt = 3.0 km/s (HR8718); ξt = 3.2 km/s (HR8304); ξt = 2.0 km/s (HR8179); ξt = 1.8 km/s (HR8778).The abundance of the iron element of stars is determined.The iron abundance is determined on the basis of comparison of the calculated and observed intensity of the spectral lines Fe (II). Calculations of the intensity of the spectral lines were carried out with the help of a program DASA, developed by CrAO. The determined abundance of Fe (II) in the atmospheres of the stars is compared with its contents in the Sun. The abundance of the iron element of the considered giants is close to the Solar one. This means that these giants were formed from a substance with the same metallicity as the Sun.