Atmospheric parameters and chemical compositions of eighteen halo OB stars
نویسندگان
چکیده
منابع مشابه
Fundamental parameters of Galactic luminous OB stars
We study the effect of microturbulence in the line formation calculations of H and He lines, in the parameter range typical for O and early B stars. We are specially interested in its effect on the determination of stellar parameters: Teff , log g and specially on the He abundance. We first analyze the behaviour of H and He model lines between 4 000 and 5 000 Å with microturbulence and find tha...
متن کاملChemical compositions of four barium stars
We obtain abundances of α, iron peak and neutron capture (n-capture) process elements in four Ba stars HD26886, HD27271, HD50082 and HD98839 based on high resolution, high signal-to-noise spectra. We find that all of these Ba stars are disk stars. Their α and iron peak elements are similar to the solar abundances. The n-capture process elements are overabundant relative to the Sun. In particula...
متن کاملChemical compositions and plasma parameters of planetary nebulae with Wolf - Rayet and wels type central stars ⋆
Aims. Chemical compositions and other properties of planetary nebulae around central stars of spectral types [WC], [WO], and wels are compared with those of 'normal' central stars, in order to clarify the evolutionary status of each type and their interrelation. Methods. We use plasma diagnostics to derive from optical spectra the plasma parameters and chemical compositions of 48 planetary nebu...
متن کاملChemical composition of halo and disk stars with overlapping metallicities
High resolution (R = 60 000), high S/N spectra have been obtained for 13 halo stars and 16 disk stars with 5400 <∼ Teff <∼ 6500 K, 4.0 <∼ logg <∼ 4.6 and overlapping metallicities in the range −1.3 <∼ [Fe/H] <∼ −0.5. Equivalent widths of weak Fe i and Fe ii lines are used to determine differential values of Teff and logg. Relative abundances of O, Na, Mg, Si, Ca, Ti, Cr, Fe, Ni, Y andBa are det...
متن کاملThe first Galactic stars and chemical enrichment in the halo
The cosmic microwave background and the cosmic expansion can be interpreted as evidence that the Universe underwent an extremely hot and dense phase about 14 Gyr ago. The nucleosynthesis computations tell us that the Universe emerged from this state with a very simple chemical composition: H, H, He, He, and traces of Li. All other nuclei where synthesised at later times. Our stellar evolution m...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Monthly Notices of the Royal Astronomical Society
سال: 1982
ISSN: 0035-8711,1365-2966
DOI: 10.1093/mnras/200.3.673