2005A&A...436..879K


C.D.S. - SIMBAD4 rel 1.7 - 2020.01.25CET13:02:23

2005A&A...436..879K - Astronomy and Astrophysics, volume 436, 879-894 (2005/6-4)

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

KARLSSON T. and GUSTAFSSON B.

Abstract (from CDS):

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. Large-scale mixing of the enriched material by turbulent motions and cloud collisions in the interstellar medium, and infall of pristine matter are taken into account. 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. (2004A&A...416.1117C) 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 α-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 some systematic deviations from observations in abundance ratios, such as 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. (2004A&A...421..613F) 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 0.05dex or better.

Abstract Copyright:

Journal keyword(s): nuclear reactions, nucleosynthesis, abundances - stars: abundances - stars: Population II - stars: supernovae: general - Galaxy: evolution - Galaxy: halo

Simbad objects: 2

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Number of rows : 2

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 HE 0107-5240 Pe* 01 09 29.1554552993 -52 24 34.203535506   15.89 15.07 15.10 14.283 CEMP-no 225 0
2 HE 1327-2326 Pe* 13 30 05.9395582011 -23 41 49.699027289 13.761 14.01 13.55 13.50 12.803 CEMP-no 211 0

    Equat.    Gal    SGal    Ecl

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2020.01.25-13:02:23

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