Results 41 to 50 of about 226,407 (198)
How Efficient is Rotational Mixing in Massive Stars ?
, 2007 The VLT-Flames Survey for Massive Stars (Evans05,Evans06) provides recise measurements of rotational velocities and nitrogen surface abundances of massive stars in the Magellanic Clouds.
Anders, P. +3 more
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The Astrophysical JournalThe physics of recombination lines in the He i singlet system is expected to be relatively simple, supported by accurate atomic models. We examine the intensities of He i singlets λ 3614, λ 3965, λ 5016, λ 6678, and λ 7281 and the triplet He i λ 5876
J. E. Méndez-Delgado +13 more
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Chemical Abundances in Planetary Nebulae [PDF]
Symposium - International Astronomical Union, 1978 PN can be divided into four types depending on their chemical composition. In order of decreasing heavy element abundances the types are: I) He and N rich, II) intermediate population, III) high velocity, and IV) halo population. The type II PN are overabundant in N and C relative to the Orion Nebula.
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Chemical abundances and metallicity of Planetary Nebulae [PDF]
Symposium - International Astronomical Union, 1997 Confrontations of the dredge-up theory with observed patterns of chemical abundances of planetary nebulae (PNs) have been carried out by many authors (see, e.g., Kaler & Jacoby 1990, 1991; Stasińska & Tylenda 1990). Although these studies suggest that the observational abundance ratios of PNs can qualitatively be explained by the current dredge-
C. Y. Zhang, S. Kwok
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Chemical abundance analysis of 19 barium stars
, 2016 We aim at deriving accurate atmospheric parameters and chemical abundances of 19 barium (Ba) stars, including both strong and mild Ba stars, based on the high signal-to-noise ratio and high resolution Echelle spectra obtained from the 2.16 m telescope at
Chen, Y. Q. +12 more
core +2 more sources
CHEMICAL ABUNDANCES IN BINARIES WITH TWIN COMPONENTS
Odessa Astronomical Publications, 2017 Procedure and some preliminary results of abundances determination in binaries with twin components from solar neighborhood are discussed. Numerical analysis were carried out by fits of synthetical spectra and COG to high resolution (R=50000) observed ...
Yu. Lyubchik +3 more
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, 2012 One of the stumbling blocks for studying the evolution of interstellar molecules is the lack of adequate knowledge of the rate co-efficients of various reactions which take place in the Interstellar medium and molecular clouds.
Ankan Das +16 more
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Non-LTE abundances of Mg and K in extremely metal-poor stars and the evolution of [O/Mg], [Na/Mg], [Al/Mg] and [K/Mg] in the Milky Way [PDF]
, 2010 LTE abundances of light elements in extremely metal-poor (EMP) stars have been previously derived from high quality spectra. New derivations, free from the NLTE effects, will better constrain the models of the Galactic chemical evolution and the yields ...
Andrievsky, S. M. +7 more
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The Missing Link of Sulfur Chemistry in TMC-1: The Detection of c-C3H2S from the GOTHAM Survey
The Astrophysical JournalWe present the spectroscopic characterization of cyclopropenethione in the laboratory and detect it in space using the Green Bank Telescope Observations of TMC-1: Hunting Aromatic Molecules survey.
Anthony J. Remijan +15 more
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Screening Earth Analog Exoplanets on the Basis of a Predicted Nitrogen over Phosphorus Ratio
The Astrophysical Journal, 2023 Since the first discovery in 1995, data for over 5300 exoplanets have been documented in the NASA archive, revealing a vast diversity. Identifying life-enabling analogs of the Earth among this rapidly expanding catalog is of major interest. The stability
Hervé Toulhoat
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