Models for extremely metal-poor halo stars

Abstract

Two alternative scenarios concerning the origin and evolution of extremely metal-poor halo stars are investigated. The first one assumes that the stars have been completely metal-free initially and produced observed carbon and nitrogen overabundances during the peculiar core helium flash typical for low-mass Population-III stars. The second scenario assumes that the initial composition resulted from a mixture of primordial material with ejecta from a single primordial supernovae. Both scenarios are shown to have problems in reproducing C, N, and O abundances simultaneously, and both disagree with observed 12C/13C-ratios,though in different directions. We concentrate on the most iron-poor, carbon-rich object of this class, HE0107-5240, and conclude that the second scenario presently offers the more promising approach to understand these objects, in particular because evolutionary tracks match observations very well.

submitted to Astron. Astrophys., 9 pages, 3 figures

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• On the origin of HE0107-5240, the most iron deficient star presently known
• On the oxygen abundance of HE0107-5240
• On the helium flash in low-mass Population III Red Giant stars
• Evolution of low-mass metal-free stars including effects of diffusion and external pollution
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Cited by in corpus (28)

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• Supernova Nucleosynthesis in Population III 13 -- 50 $M_{\odot }$ Stars and Abundance Patterns of Extremely Metal-Poor Stars
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• HE1327-2326, an unevolved star with [Fe/H]<-5.0. I. A Comprehensive Abundance Analysis
• 3D Hydrodynamical Simulations of Surface Convection in Red Giant Stars. Impact on spectral line formation and abundance analysis
• Classical Cepheid Pulsation Models. X. The Period-Age Relation
• Evolution and Nucleosynthesis of Extremely Metal Poor & Metal-Free Low- and Intermediate-Mass Stars I: Stellar Yield Tables and the CEMPs
• Population Synthesis of Binary Carbon-enhanced Metal-poor Stars
• The Origin of Carbon-Enhancement and Initial Mass Function of Extremely Metal-Poor Stars in the Galactic Halo
• The chemical compositions of the extreme halo stars HE0107-5240 and HE1327-2326 inferred from 3D hydrodynamical model atmospheres
• CS 30322-023: an ultra metal-poor TP-AGB star?
• New analysis of the two carbon-rich stars CS 22948-27 and CS 29497-34 : binarity and neutron-capture elements
• The core helium flash revisited: II. Two and three-dimensional hydrodynamic simulations
• Stellar Yields of Rotating First Stars. I. Yields of Weak Supernovae and Abundances of Carbon-enhanced Hyper Metal Poor Stars
• Old open clusters in the inner Galaxy: FSR1744, FSR89 and FSR31
• Evolution and nucleosynthesis of primordial low mass stars
• The core helium flash revisited III. From Pop I to Pop III stars
• Investigating the age and structure of the infrared old open clusters LK1, LK10, FSR1521 and FSR1555
• A phenomenological modification of thermohaline mixing in globular cluster red giants
• Multidimensional hydrodynamic simulations of the hydrogen injection flash
• S-process in low-mass extremely metal-poor stars
• Horizontal branch morphology: A new photometric parametrization
• Evolution of Low-Mass Population III Stars
• Multi-Conjugate Adaptive Optics VLT imaging of the distant old open cluster FSR1415
• Chemical tracers of high-metallicity environments
• The old Galactic open clusters FSR1716 and Czernik23
• Combined Nucleosynthetic Yields of Multiple First Stars
• The origin of HE0107-5240 and the production of O and Na in extremely metal-poor stars