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 کاملThe Galactic warp in OB stars from Hipparcos
The kinematics of distant OB stars perpendicular to the Galactic plane, inferred from proper motions in the Hipparcos catalogue, are analysed and compared to the kinematic signature that would be induced by a long-lived Galactic warp. Previously we reported that the kinematics of the OB stars toward the anticenter were inconsistent with the assumption of a long-lived warp (Smart et al. 1998), s...
متن کاملThe Chemical Composition of Red Giant Branch Stars in the Galactic Globular Clusters Ngc
We present radial velocities and chemical abundances for red giant branch stars in the Galactic bulge globular clusters NGC 6342 and NGC 6366. The velocities and abundances are based on measurements of high resolution (R & 20,000) spectra obtained with the MMT–Hectochelle and WIYN–Hydra spectrographs. We find that NGC 6342 has a heliocentric radial velocity of +112.5 km s (σ = 8.6 km s), NGC 63...
متن کاملThe role of massive stars in galactic chemical evolution
I will review the role of massive stars in galactic evolution both from the nucleosynthesis and energetics point of view. In particular, I will highlight some important observational facts explained by means of massive stars in galaxies of different morphological type: the Milky Way, ellipticals and dwarf spheroidals. I will describe first the time-delay model and its interpretation in terms of...
متن کاملB stars and the chemical evolution of the Galactic disk ?
We determine stellar parameters and He, C, N, O, Mg, Al, and Si abundances of a sample of 16 early B mainsequence stars in galactocentric distances of RGC = 5–14 kpc by reanalyzing and extending the observations of Kaufer et al. (1994) towards the Galactic center. The analysis uses Kurucz atlas 9 lte atmospheres and Giddings-Butler detail/surface non-lte line formation. It is shown that beside ...
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ژورنال
عنوان ژورنال: Astronomy & Astrophysics
سال: 2002
ISSN: 0004-6361,1432-0746
DOI: 10.1051/0004-6361:20020400