Discovery of three lead-rich stars

  title={Discovery of three lead-rich stars},
  author={Sophie Van Eck and Stephane Goriely and Alain Jorissen and Bertrand Plez},
About half of the stable nuclei heavier than iron are believed to be synthesized during the late stages of evolution of stars with masses in the range 0.8–8 solar masses. These elements are then expelled into the interstellar medium through stellar winds after being ‘dredged up’ towards the surface of the stars. These processes occur when the star is in the ‘asymptotic giant branch’ (AGB) phase of its life. Nuclei (mainly iron) deep inside the star slowly capture neutrons and progressively… 
Nucleosynthesis of s-elements in zero-metal AGB stars
Contrary to previous expectations, recent evolutionary models of zero-metallicity stars show that the development of mixing episodes at the beginning of the AGB phase allows low- and
The s process in AGB stars as constrained by a large sample of barium stars
Context. Barium (Ba) stars are dwarf and giant stars enriched in elements heavier than iron produced by the slow neutron-capture process (s process). These stars belong to binary systems in which the
Stellar Sources for Heavy r-Process Nuclei
The stellar sites and the complete mechanism of r-process nucleosynthesis are still unresolved issues. From consideration of the observed abundances in metal-poor stars, it is proposed that the
Observational nuclear astrophysics: neutron-capture element abundances in old, metal-poor stars
The chemical abundances of metal-poor stars provide a great deal of information regarding the individual nucleosynthetic processes that created the observed elements and the overall process of
The Dawes Review 2: Nucleosynthesis and Stellar Yields of Low- and Intermediate-Mass Single Stars
Abstract The chemical evolution of the Universe is governed by the chemical yields from stars, which in turn are determined primarily by the initial stellar mass. Even stars as low as 0.9 M⊙ can, at
Binary Blue Metal-poor Stars: Evidence for Asymptotic Giant Branch Mass Transfer
We present new abundance analyses of six blue metal-poor (BMP) stars with very low iron abundances ([Fe/H] < -2), based on new high-resolution echelle spectra. Three are spectroscopic binaries, and
The origin of the lead-rich stars in the Galactic halo: investigation of model parameters for the s-process
Several stars at the low-metallicity extreme of the Galactic halo show large spreads of lead and associated 'heavy' s-process elements ([Pb/hs]). Theoretically, an s-process pattern should be
More lead stars
The standard model for the operation of the s-process in asymptotic giant branch (AGB) stars predicts that low-metallicity ([Fe/H] ≲ -1) AGB stars should exhibit large overabundances of Pb and Bi as
We examine the Pb and Th abundances in 27 metal-poor stars (−3.1< [Fe/H] <−1.4) whose very heavy metal (Z > 56) enrichment was produced only by the rapid (r-) nucleosynthesis process. New abundances
Mass Fraction of 13 C-Pocket in Metal-Poor AGB Stars and the Primary Nature of Neutron Source
Chemical abundances of very metal-poor s-rich stars contain excellent information to set new constraints on models of neutron-capture processes at low metallicity. Using the parametric approach based


The Origin of Extremely Metal-poor Carbon Stars and the Search for Population III
It is shown that low-mass, extremely metal-poor stars evolve into carbon stars along paths that are quite different from those followed by more metal-rich stars of younger populations, allowing us, in principle, to distinguish the brightest survivors of the first generations of stars formed in the universe (Population III carbon stars) from stars belonging to younger populations.
We present a new analysis of neutron capture occurring in low-mass asymptotic giant branch (AGB) stars suffering recurrent thermal pulses. We use dedicated evolutionary models for stars of initial
Galactic Chemical Evolution of Heavy Elements: From Barium to Europium
We follow the chemical evolution of the Galaxy for elements from Ba to Eu, using an evolutionary model suitable for reproducing a large set of Galactic (local and nonlocal) and extragalactic
Evidence of Multiple r-Process Sites in the Early Galaxy: New Observations of CS 22892–052
The concordance of scaled solar r-process and CS 22892-052 abundances breaks down for the lighter neutron-capture elements, supporting previous suggestions that different r- process production sites are responsible for lighter and heavier neutron- capture elements.
Hubble Space Telescope Observations of Neutron-Capture Elements in Very Metal Poor Stars
Using the Goddard High-Resolution Spectrograph (GHRS) of the Hubble Space Telescope (HST) we have detected the neutron-capture elements osmium, platinum, and lead in the very metal poor ([Fe/H] ≃
Detection of Lead in the Carbon-rich, Very Metal-poor Star LP 625-44: A Strong Constraint on s-Process Nucleosynthesis at Low Metallicity.
The detection of Pb makes it possible, for the first time, to compare model predictions of s-process nucleosynthesis in AGB stars with observations of elements between Sr and Pb, and the Pb abundance is significantly lower than the prediction of recent models.
The Binary Nature of the Barium and CH Stars. III. Orbital Parameters
Results are presented from a 10-year program to monitor the velocity variations of Ba II and CH stars, showing that all Ba II and CH stars are binaries. Radial-velocity observations for Ba II and CH
The CH Stars. III. Heavy Element Abundances
The s-process abundances in seven CH giants have been derived. Large enhancement of s-process elements relative to solar values are found, [s/Fe]=+1.0 to +2.0. In addition, the heavy s-process peak
Neutron-capture nucleosynthesis in AGB stars
Recent AGB models including diffusive overshoot or rotational effects suggest the partial mixing (PM) of protons from the H-rich envelope into the C-rich layers during the third dredge-up. In order
Mixing and nucleosynthesis in rotating TP-AGB stars
We present the first evolutionary models of interme- diate mass stars up to their thermal pulses which include effects of rotation on the stellar structure as well as rotationally in- duced mixing of