Results 161 to 170 of about 226,407 (198)
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Chemical Abundances of Symbiotic Giants
EAS Publications Series, 2015High resolution (R ∼ 50000), near-IR spectra were used to measure photospheric abundances of CNO and elements around the iron peak for 24 symbiotic giants. Spectrum synthesis was employed using local thermal equilibrium and hydrostatic model atmospheres. The metallicities are distributed in a wide range with maximum around [ Fe / H ] ∼−0.4 – − 0.3 dex.
C. Gałan +3 more
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Chemical abundances in cold, dark interstellar clouds
Icarus, 1991The Sun may well have formed in the type of interstellar cloud currently referred to as a cold, dark cloud. We present current tabulations of the totality of known interstellar molecules and of the subset which have been identified in cold clouds. Molecular abundances are given for two such clouds which show interesting chemical differences in spite ...
Irvine, William M., Ohishi, M, Kaifu, N
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1988
The precise determination of chemical abundances in stars is the key to a number of important disciplines in modern astrophysics including stellar evolution and nucleosynthesis as well as the chemical and dynamical evolution of the Galaxy. The basic transport mechanisms in stellar atmospheres rule the observational aspects of stellar surfaces which are
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The precise determination of chemical abundances in stars is the key to a number of important disciplines in modern astrophysics including stellar evolution and nucleosynthesis as well as the chemical and dynamical evolution of the Galaxy. The basic transport mechanisms in stellar atmospheres rule the observational aspects of stellar surfaces which are
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Chemical Abundances in Molecular Clouds
1987At present approximately 70 interstellar molecules are known. We discuss methods for determining chemical abundances in interstellar clouds and present results for the best studied regions, which include the “spiral arm” clouds seen towards distant continuum sources, quiescent dark and giant clouds, and the gas in regions of active star formation.
W. M. Irvine +2 more
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Chemical Abundances in Meteorites
1988Some 4.6 billion years ago contraction and subsequent collapse of an interstellar cloud led to the formation of the solar system. The ratio of heavy elements to hydrogen, increasing continuously in interstellar material, due to the addition of freshly synthesized material from stars, was frozen in for the solar system at this point of time.
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1981
Photoelectric, filter photometry and spectrophotometry allow us to derive absolute abundances for a number of species in comets. Despite large differences in morphology, in gas-to-dust ratio, and in dynamical age, there appears to be remarkably little variation from comet to comet in the relative production rates of the species studied thus far.
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Photoelectric, filter photometry and spectrophotometry allow us to derive absolute abundances for a number of species in comets. Despite large differences in morphology, in gas-to-dust ratio, and in dynamical age, there appears to be remarkably little variation from comet to comet in the relative production rates of the species studied thus far.
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Chemical Abundances in Galaxies
1988This article is intended as a brief overview of chemical abundances in galaxies other than our own. Attention is concentrated on global properties of ellipticals and spirals, and the methods by which abundances are estimated. References are predominantly to work which has appeared since the review of Pagel and Edmunds (1981).
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