The r-Process in Metal Poor Stars and Black Hole Formation

Abstract

Nucleosynthesis of heavy nuclei in metal-poor stars is generally thought to occur via the r-process because the r-process is a primary process that would have operated early in the Galaxy's history. This idea is strongly supported by the fact that the abundance pattern in many metal-poor stars matches well the inferred Solar r-process abundance pattern in the mass range between the second and third r-process abundance peaks. Nevertheless, a significant number of metal-poor stars do not share this standard r-process template. In this Letter we suggest that the nuclides observed in many of these stars are produced by the r-process, but that it is prevented from running to completion in more massive stars by collapse to black holes before the r-process is completed, creating a "truncated r-process," or "tr-process." We find that the observed fraction of tr-process stars is qualitatively what one would expect from the initial mass function, and that an apparent sharp truncation observed at around mass 160 could result from a combination of collapses to black holes and the difficulty of observing the higher mass rare earths. We test the tr-process hypothesis with r-process calculations that are terminated before all r-process trajectories have been ejected. We find qualitative agreement between observation and theory when black hole collapse and observational realities are taken into account.

References in corpus (5)

• Neutron-capture elements in the very metal-poor star HD122563
• Neutron-capture elements in the very metal-poor star HD88609: another st ar with excesses of light neutron-capture elements
• Integrated Nucleosynthesis in Neutrino Driven Winds
• Nucleosynthesis Modes in the High-Entropy-Wind of Type II Supernovae: Comparison of Calculations with Halo-Star Observations
• Abundances of Sr, Y, and Zr in Metal-Poor Stars and Implications for Chemical Evolution in the Early Galaxy

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• High-Resolution Spectroscopic Study of Extremely Metal-Poor Star Candidates from the SkyMapper Survey
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• Metal-Poor Stars Observed with the Magellan Telescope II. Discovery of Four Stars with [Fe/H] < -3.5
• The New Model of Chemical Evolution of r-process Elements Based on The Hierarchical Galaxy Formation I: Ba and Eu
• Abundance patterns of the light neutron-capture elements in very and extremely metal-poor stars
• Explaining the Sr and Ba Scatter in Extremely Metal-Poor Stars
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• Impact of new data for neutron-rich heavy nuclei on theoretical models for $r$-process nucleosynthesis
• The $Gaia$-ESO Survey: the inner disk intermediate-age open cluster NGC 6802
• The Origin of the Heaviest Metals in Most Ultra-Faint Dwarf Galaxies
• High resolution study of the abundance pattern of the heavy elements in very metal-poor field stars
• Observational nuclear astrophysics: neutron-capture element abundances in old, metal-poor stars
• Estimating R-Process Yields from Abundances of the Metal-Poor Stars
• The Origin of the Metal-Poor Common Proper Motion Pair HD 134439/134440: Insights from New Elemental Abundances
• Dependence of the Sr-to-Ba and Sr-to-Eu Ratio on the Nuclear Equation of State in Metal Poor Halo Stars