Abstract
view Abstract Citations (168) References (124) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Subdwarf Studies. IV. Element Abundance Ratios in Extremely Metal-deficient Stars Ryan, Sean G. ; Norris, John E. ; Bessell, M. S. Abstract High-resolution spectra of 19 metal-deficient proper motion stars were examined for basic trends in the abundances for iron and other elements. Results indicate that there is a mild support for the claim by Tomkin et al. (1986) and Carbon et al. (1987) of an upturn in the C/Fe ratio at Fe/H of -2.0, which might reflect an overproduction of carbon in the supernovae of 200-solar-mass, zero-initial-metallicity stars. The abundance ratios of Mg, Si, Ca, Ti, Cr, Sc, and Mn relative to Fe are found to extend the uniform trends previously reported for stars with Fe/H ratio between -2.5 and -1.0, down to at least Fe/H of -3.5. The Ni element is not as overabundant as was reported by Luck and Bond (1983, 1985), and Al element is overabundant with respect to both Fe and Mg. It was found that halo dwarfs have an Mn/Fe underabundance of -0/33 dex, and that the spread in relative abundances of Sr in the most metal-deficient stars is greater than 1 decade. Publication: The Astronomical Journal Pub Date: July 1991 DOI: 10.1086/115878 Bibcode: 1991AJ....102..303R Keywords: Abundance; Metallicity; Subdwarf Stars; Cosmochemistry; Spectral Line Width; Stellar Spectra; Stellar Spectrophotometry; Astrophysics; STARS: SUBDWARFS full text sources ADS | data products SIMBAD (17) Related Materials (3) Part 1: 1989AJ.....98.1693R Part 2: 1991AJ....101.1835R Part 3: 1991AJ....101.1865R
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