Explaining the Ba, Y, Sr, and Eu abundance scatter in metal-poor halo stars: constraints to the r-process

Abstract

Context. Thanks to the heroic observational campaigns carried out in recent years we now have large samples of metal-poor stars for which measurements of detailed abundances exist. [...] These data hold important clues on the nature of the contribution of the first stellar generations to the enrichment of our Galaxy. Aims. We aim to explain the scatter in Sr, Ba, Y, and Eu abundance ratio diagrams unveiled by the metal-poor halo stars. Methods. We computed inhomogeneous chemical evolution models for the Galactic halo assuming different scenarios for the r-process site: the electron-capture supernovae (EC) and the magnetorotationally driven (MRD) supernovae scenario. We also considered models with and without the contribution of fast-rotating massive stars (spinstars) to an early enrichment by the s-process. A detailed comparison with the now large sample of stars with measured abundances of Sr, Ba, Y, Eu, and Fe is provided (both in terms of scatter plots and number distributions for several abundance ratios). Results. The scatter observed in these abundance ratios of the very metal-poor stars (with [Fe/H] < -2.5) can be explained by combining the s-process production in spinstars, and the r-process contribution coming from massive stars. For the r-process we have developed models for both the EC and the MRD scenario that match the observations. Conclusions. With the present observational and theoretical constraints we cannot distinguish between the EC and the MRD scenario in the Galactic halo. Independently of the r-process scenarios adopted, the production of elements by an s-process in spinstars is needed to reproduce the spread in abundances of the light neutron capture elements (Sr and Y) over heavy neutron capture elements (Ba and Eu). We provide a way to test our suggestions by means of the distribution of the Ba isotopic ratios in a [Ba/Fe] or [Sr/Ba] vs. [Fe/H] diagram.

14 pages, 7 figures, accepted for publication in Astronomy and Astrophysics

References in corpus (16)

• Magnetorotationally driven Supernovae as the origin of early galaxy $r$-process elements?
• First Stars VIII -- Enrichment of the neutron-capture elements in the early Galaxy
• Near-UV Observations of HD221170: New Insights into the Nature of r-Process-Rich Stars
• A strong case for fast stellar rotation at very low metallicities
• Production of Light Element Primary Process nuclei in neutrino-driven winds
• The Frequency of Carbon-Enhanced Metal-Poor Stars in the Galaxy from the HERES sample
• The s process in massive stars at low metallicity. Effect of primary N14 from fast rotating stars
• The stellar content of the Hamburg/ESO survey. IV. Selection of candidate metal-poor stars
• Dynamical r-process studies within the neutrino-driven wind scenario and its sensitivity to the nuclear physics input
• New Extremely Metal-Poor Stars in the Galactic Halo
• Stellar Archaeology -- Exploring the Universe with Metal-Poor Stars
• CS 30322-023: an ultra metal-poor TP-AGB star?
• A new imprint of fast rotators: low 12C/13C ratios in extremely metal-poor halo stars
• An inhomogeneous model for the Galactic halo: a possible explanation for the spread observed in s- and r-process elements
• Carbon and Strontium Abundances of Metal-Poor Stars
• The Hobby-Eberly Telescope "Chemical Abundances of Stars in the Halo" (CASH) Project. I. The Lithium-, s-, and r-Enhanced Metal-Poor Giant HKII 17435-00532

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