Stochastic chemical enrichment in metal-poor systems II. Abundance ratios and scatter

Abstract

A stochastic model of the chemical enrichment of metal-poor systems by core-collapse supernovae is used to study the scatter in stellar abundance ratios. The resulting scatter in abundance ratios, e.g. as functions of the overall metallicity, is demonstrated to be crucially dependent on the as yet uncertain supernovae yields. The observed abundance ratios and their scatters therefore have diagnostic power as regards the yields. The relatively small star-to-star scatter observed in many chemical abundance ratios, e.g. by Cayrel et al. (2004) for stars down to [Fe/H] = -4, is tentatively explained by the averaging of a large number of contributing supernovae and by the cosmic selection effects favoring contributions from supernovae in a certain mass range for the most metal-poor stars. The scatter in observed abundances of alpha-elements is understood in terms of observational errors only, while additional spread in yields or sites of nucleosynthesis may affect the odd-even elements Na and Al. For the iron-group elements we find systematically too high predicted Cr/Fe and Cr/Mg ratios, as well as differences between the different sets of yields, both in terms of predicted abundance ratios and scatter. The semi-empirical yields recently suggested by Francois et al. (2004) are found to lead to scatter in abundance ratios significantly greater than observed, when applied in the inhomogeneous models. "Spurs", very narrow sequences in abundance-ratio diagrams, may disclose a single-supernova origin of the elements of the stars on the sequence. Verification of the existence of such features, called single supernova sequences (SSSs), is challenging. This will require samples of several hundred stars with abundance ratios observed to accuracies of 0.05 dex or better.

arXiv comment19 pages, 20 figures, accepted for publication in Astronomy & Astrophysics

References in corpus (20)

• First stars V - Abundance patterns from C to Zn and supernova yields in the early Galaxy
• Nucleosynthesis of Zinc and Iron-Peak Elements in Pop III Type II Supernovae : Comparison with abundances of Very Metal-Poor Halo Stars
• The O-Na and Mg-Al Anticorrelations in Turn-Off and early Subgiants in Globular Clusters
• Explosive yields of massive stars from Z=0 to Z=Zsun
• Nucleosynthesis in Type II Supernovae
• The evolution of the Milky Way from its earliest phases : constraints on stellar nucleosynthesis
• Extremely Metal-Poor Stars. VIII. High-Resolution, High-Signal-To-Noise Analysis of Five Stars with [Fe/H] < -3.5
• HE0107-5240, A Chemically Ancient Star.I. A Detailed Abundance Analysis
• Abundances In Very Metal Poor Dwarf Stars
• The first generation of stars: first steps towards chemical evolution of galaxies
• Stellar Archaeology: a Keck Pilot Program on Extremely Metal-Poor Stars from the Hamburg/ESO Survey. II. Abundance Analysis
• Chemical Evolution of the Galactic Halo through Supernova-Induced Star Formation and Its Implication for Population III Stars
• Mg abundances in metal-poor halo stars as a tracer of early Galactic mixing
• Massive Field Stars and the Stellar Clustering Law
• Implications of O and Mg abundances in metal-poor halo stars for stellar iron yields
• Excavation of the first stars
• Non-LTE Abundances and Consequences for the Evolution of the alpha elements in the Galaxy
• The number and metallicities of the most metal-poor stars
• A New Look at Simple Inhomogeneous Chemical Evolution
• Chemical abundance patterns -- fingerprints of nucleosynthesis in the first stars

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