منابع مشابه
Elemental Abundances in PG 1159 Stars
The hydrogen-deficiency in extremely hot post-AGB stars of spectral class PG1159 is probably caused by a (very) late helium-shell flash or a AGB final thermal pulse that consumes the hydrogen envelope, exposing the usuallyhidden intershell region. Thus, the photospheric elemental abundances of these stars allow to draw conclusions about details of nuclear burning and mixing processes in the pre...
متن کاملElemental abundances of carbon, nitrogen, and oxygen in carbon stars
The elemental abundances of carbon, nitrogen, and oxygen in three carbon stars (TX Psc, V Aql, and BL Ori) are determined from high-resolution infrared spectra in a selfconsistent manner, with the dependence of the atmospheric structure on the chemical composition fully taken into account. For this purpose, we have constructed a grid of line-blanketed model atmospheres using a revised Band Mode...
متن کاملElemental Abundances in Five Stars in M54, a Globular Cluster Associated with the Sagittarius Galaxy
Chemical abundances in Ðve stars in M54, a globular cluster associated with the Sagittarius dwarf galaxy, have been determined using high-resolution echelle spectra. We Ðnd the cluster to have [Fe/H]\ [1.55 and possibly halo-normal abundance patterns, although the [O/Fe] and [a/Fe] ratios lie between solar and the normal halo values. One star shows the combination of low oxygen and enhanced Na ...
متن کاملAbundances in stars with exoplanets
Extensive spectroscopic studies of stars with and without planets have concluded that stars hosting planets are significantly more metal-rich than those without planets. More subtle trends of different chemical elements begin to appear as the number of detected extrasolar planetary systems continues to grow. I review our current knowledge concerning the observed abundance trends of various chem...
متن کاملAbundances in Metal-rich Stars ?
We have derived elemental abundances of O, Ni as well as for a number of s-elements for 47 G and K dwarf, with Me/H]> 0:1 dex. The selection of stars was based on their kinematics as well as on their uvby ?-photometry. One sample of stars on rather eccentric orbits traces the chemical evolution interior to the solar orbit and another, on circular orbits, the evolution around the solar orbit. A ...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 1993
ISSN: 0074-1809
DOI: 10.1017/s0074180900171918