منابع مشابه
The Rise of the Agb in the Galactic Halo: Mg Isotopic Ratios and High Precision Elemental Abundances in M71 Giants
High-resolution (R ≈ 100 000), high signal-to-noise spectra of M71 giants have been obtained with HIRES at the Keck I Telescope in order to measure their Mg isotopic ratios, as well as elemental abundances of C, N, O, Na, Mg, Al, Si, Ca, Ti, Ni, Zr and La. We demonstrate that M71 has two populations, the first having weak CN, normal O, Na, Mg, and Al, and a low ratio of Mg/Mg (∼4%) consistent w...
متن کاملThe Isotopic Abundances of Magnesium in Stars
Isotopic abundance ratios Mg:Mg:Mg are derived for 20 stars from highresolution spectra of the MgH A-X 0-0 band at 5140Å. With the exception of the weak G-band giant HR 1299, the stars are dwarfs that sample the metallicity range -1.8 < [Fe/H] <0.0. The abundance of Mg and Mg relative to the dominant isotope Mg decreases with decreasing [Fe/H] in fair accord with predictions from a recent model...
متن کاملIsotopic abundances of carbon and nitrogen in Jupiter-family and Oort Cloud comets
The 12C14N/12C15N and 12C14N/13C14N isotopic ratios are determined for the first time in a Jupiter-family comet, 88P/1981 Q1 Howell, and in the chemically peculiar Oort Cloud comet C/1999 S4 (LINEAR). By comparing these measurements to previous ones derived for six other Oort Cloud comets (including one of Halley-type), we find that both the carbon and nitrogen isotopic ratios are constant with...
متن کاملIsotopic Carbon
biometry are laborious and inefficient." In their place he describes methods, admittedly crude, which serve well for exploratory investigations. These include standardized photographs, pictorialized scatter diagrams, ideographs, hybrid indices, and "radiate indicators." Properly used, these seem not to be laborious or inefficient; more important perhaps is their appeal to many non-mathematical ...
متن کاملLithium Isotopic Abundances in Metal-poor Halo Stars
Very high-quality spectra of 24 metal-poor halo dwarfs and subgiants have been acquired with ESO’s VLT/UVES for the purpose of determining Li isotopic abundances. The derived 1D, nonLTE Li abundances from the Li i 670.8 nm line reveal a pronounced dependence on metallicity but with negligible scatter around this trend. Very good agreement is found between the abundances from the Li i 670.8 nm l...
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ژورنال
عنوان ژورنال: The Astronomical Journal
سال: 1997
ISSN: 0004-6256
DOI: 10.1086/118253