Asymptotic Giant Branch models at very low metallicity

Abstract

In this paper we present the evolution of a low mass model (initial mass M=1.5 Msun) with a very low metal content (Z=5x10^{-5}, equivalent to [Fe/H]=-2.44). We find that, at the beginning of the AGB phase, protons are ingested from the envelope in the underlying convective shell generated by the first fully developed thermal pulse. This peculiar phase is followed by a deep third dredge up episode, which carries to the surface the freshly synthesized 13C, 14N and 7Li. A standard TP-AGB evolution, then, follows. During the proton ingestion phase, a very high neutron density is attained and the s-process is efficiently activated. We therefore adopt a nuclear network of about 700 isotopes, linked by more than 1200 reactions, and we couple it with the physical evolution of the model. We discuss in detail the evolution of the surface chemical composition, starting from the proton ingestion up to the end of the TP-AGB phase.

Accepted for Publication on PASA

References in corpus (4)

• Carbon-Enhanced Metal-Poor Stars. III. Main-Sequence Turn-Off Stars from the SDSS/SEGUE Sample
• Thermohaline mixing and gravitational settling in carbon-enhanced metal-poor stars
• CS22964-161: A Double-Lined Carbon- and s-Process-Enhanced Metal-Poor Binary Star
• 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

Cited by in corpus (51)

• The s Process: Nuclear Physics, Stellar Models, Observations
• The s process in asymptotic giant branch stars of low metallicity and the composition of carbon-enhanced metal-poor stars
• The s-Process in Low Metallicity Stars. II. Interpretation of High-Resolution Spectroscopic Observations with AGB models
• Convective-reactive proton-C12 combustion in Sakurai's object (V4334 Sagittarii) and implications for the evolution and yields from the first generations of stars
• The intermediate neutron-capture process and carbon-enhanced metal-poor stars
• The Ubiquity of the Rapid Neutron-Capture Process
• NuGrid Stellar Data Set. II. Stellar Yields from H to Bi for Stellar Models with Mzams = 1 to 25Msun and Z = 0.0001 to 0.02
• s-Process in Low Metallicity Stars. I. Theoretical Predictions
• Deep Mixing in Evolved Stars: I. The Effect of Reaction Rate Revisions from C to Al
• s-Process in Low Metallicity Stars. III. Individual analysis of CEMP-s and CEMP-s/r with AGB models
• Frontiers in Nuclear Astrophysics
• Global non-spherical oscillations in 3-D $4\pi$ simulations of the H-ingestion flash
• H ingestion into He-burning convection zones in super-AGB stellar models as a potential site for intermediate neutron-density nucleosynthesis
• Three carbon-enhanced metal-poor dwarf stars from the SDSS - Chemical abundances from CO^5BOLD 3D hydrodynamical model atmospheres
• The Diverse Origins of Neutron-Capture Elements in the Metal-Poor Star HD 94028: Possible Detection of Products of i-process Nucleosynthesis
• 3D hydrodynamical simulations of a proton ingestion episode in a low-metallicity asymptotic giant branch star
• LUNA: Status and Prospects
• The s Process and Beyond
• New determination of the 13C(a, n)16O reaction rate and its influence on the s-process nucleosynthesis in AGB stars
• Learning about the intermediate neutron-capture process from lead abundances
• The importance of the 13C(alpha,n)16O reaction in Asymptotic Giant Branch stars
• The impact of updated Zr neutron-capture cross sections and new asymptotic giant branch models on our understanding of the s process and the origin of stardust
• Constraints of the physics of low-mass AGB stars from CH and CEMP stars
• How plausible are the proposed formation scenarios of CEMP-r/s stars?
• Convective H-He Interactions in Massive Population III Stellar Evolution Models
• The intermediate neutron capture process. III. The i-process in AGB stars of different masses and metallicities without overshoot
• The occurrence of nitrogen-enhanced metal-poor stars: implications for the initial mass function in the early Galactic halo
• Post-AGB stars in the Magellanic Clouds and neutron-capture processes in AGB stars
• Deep underground laboratory measurement of ${}^{13}$C($\alpha$,$n$)${}^{16}$O in the Gamow windows of the $s$- and $i$-processes
• Magnetic-buoyancy-induced mixing in AGB Stars: fluorine nucleosynthesis at different metallicities
• Spectroscopic study of CEMP-(s & r/s) stars- Revisiting classification criteria and formation scenarios, highlighting i-process nucleosynthesis
• [O/Fe] Estimates for Carbon-Enhanced Metal-Poor Stars from Near-IR Spectroscopy
• The intermediate neutron capture process II.Nuclear uncertainties
• S-process in low-mass extremely metal-poor stars
• Chemical Evolution of R-process Elements in Stars (CERES). I. Stellar parameters and chemical abundances from Na to Zr
• The impact of (n,$\gamma$) reaction rate uncertainties of unstable isotopes on the i-process nucleosynthesis of the elements from Ba to W
• Barium stars as tracers of s-process nucleosynthesis in AGB stars II. Using machine learning techniques on 169 stars
• Fates of the oldest intermediate-mass stars - Primordial to Extremely Metal-Poor AGB and Super-AGB Stars: White Dwarf or Supernova progenitors
• Synthesis of thorium and uranium in asymptotic giant branch stars
• Modelling the nucleosynthetic properties of carbon-enhanced metal-poor RR Lyrae stars
• Nucleosynthetic yields of Z=$10^{-5}$ intermediate-mass stars
• The peculiar abundances of HE 1005-1439. A carbon-enhanced extremely metal-poor star contaminated with products of both s-and i-process nucleosynthesis
• Barium stars as tracers of s-process nucleosynthesis in AGB stars III. Systematic deviations from the AGB models
• Nucleosynthetic yields of intermediate-mass primordial to extremely metal-poor stars
• Nuclear Level Density and $\gamma$-ray Strength Function of ${}^{67}\mathrm{Ni}$ and the impact on the i-process
• Spectroscopic study of Ba and CEMP-s stars: Mass distribution of AGB progenitors
• Optical and NIR spectroscopy of cool CEMP stars to probe the nucleosynthesis in low mass AGB binary system
• Statistical framework for nuclear parameter uncertainties in nucleosynthesis modeling of r- and i-process
• Gas and dust from extremely metal-poor AGB stars
• A comparative study on three modes of s-process nucleosynthesis in extremely metal-poor AGB stars
• CEMP-s and CEMP-s/r stars: last update