Improved Laboratory Transition Probabilities for Sm<scp>ii</scp>and Application to the Samarium Abundances of the Sun and Three<i>r</i>‐Process–rich, Metal‐poor Stars

Lawler, J. E.; Hartog, E. A. Den; Sneden, Christopher; Cowan, J. J.

doi:10.1086/498213

Cited by 121 publications

(100 citation statements)

References 97 publications

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“…We show the same comparisons in Figure 2, but now with recent new experimental data (improved laboratory transition probabilities) for Nd [4], Sm [5], Gd [6] and Ho [7]. It is seen that the scatter has been significantly reduced and that the abundances are consistent from starto-star and with the solar system r-process only values.…”

Section: Abundances and Atomic Datasupporting

confidence: 67%

Abundance Signatures in Halo Stars: Clues to Nucleosynthesis in the First Stars

Cowan¹,

Sneden²,

Lawler³

et al. 2008

AIP Conference Proceedings

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Abstract.We are using both space-based (Hubble Space Telescope, HST) and ground-based telescopes to make extensive studies of Galactic halo stars. These stars contain the nucleosynthesis products (from the rapid neutron capture process, i.e., the rprocess) from the earliest generations of stars -the progenitors of the halo stars. The observed stellar abundance distributions -from the lightest neutron-capture elements, such as Ge, along with some of the heaviest, including Pt -are providing new clues about the earliest Galactic r-process nucleosynthesis. These in turn will help to identify the characteristics and nature of the first stars in the Galaxy.

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Section: Abundances and Atomic Datasupporting

confidence: 67%

Abundance Signatures in Halo Stars: Clues to Nucleosynthesis in the First Stars

Cowan¹,

Sneden²,

Lawler³

et al. 2008

AIP Conference Proceedings

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“…For the analysis of the samarium lines we applied the values from Lawler et al (2006). Europium lines were detected in all stars, and abundances were determined with the help of spectrum synthesis and line profile fitting, taking into account the HFS.…”

Section: Neutron-capture Elementsmentioning

confidence: 99%

Three carbon-enhanced metal-poor dwarf stars from the SDSS

Behara

Bonifacio

Ludwig

et al. 2010

A&A

135

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Context. The origin of carbon-enhanced metal-poor stars enriched with both s and r elements is highly debated. Detailed abundances of these types of stars are crucial to understand the nature of their progenitors. Aims. The aim of this investigation is to study in detail the abundances of SDSS J1349-0229, SDSS J0912+0216 and SDSS J1036+1212, three dwarf CEMP stars, selected from the Sloan Digital Sky Survey. Methods. Using high resolution VLT/UVES spectra (R ∼ 30 000) we determine abundances for Li, C, N, O, Na, Mg, Al, Ca, Sc, Ti, Cr, Mn, Fe, Co, Ni and 21 neutron-capture elements. We made use of CO 5 BOLD 3D hydrodynamical model atmospheres in the analysis of the carbon, nitrogen and oxygen abundances. NLTE corrections for Ci and Oi lines were computed using the Kiel code. Results. We classify SDSS J1349-0229 and SDSS J0912+0216 as CEMP-r+s stars. SDSS J1036+1212 belongs to the class CEMPno/s, with enhanced Ba, but deficient Sr, of which it is the third member discovered to date. Radial-velocity variations have been observed in SDSS J1349-0229, providing evidence that it is a member of a binary system. Conclusions. The chemical composition of the three stars is generally compatible with mass transfer from an AGB companion. However, many details remain difficult to explain. Most notably of those are the abundance of Li at the level of the Spite plateau in SDSS J1036+1212 and the large over-abundance of the pure r-process element Eu in all three stars.

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“…Recent transition probabilities and line positions for Nd, Sm, Er and Hf lines were also included. The data was taken from Den Hartog et al (2003) and Lawler et al (2006Lawler et al ( , 2007Lawler et al ( , 2008.…”

Section: Line Datamentioning

confidence: 99%

The Hamburg/ESO R-process enhanced star survey (HERES)

Hayek

Wiesendahl

Christlieb

et al. 2009

A&A

109

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AstrophysicsThe Hamburg/ESO R-process enhanced star survey (HERES) The analysis is based on high-quality VLT/UVES spectra and MARCS model atmospheres. We detect lines of 15 heavy elements in the spectrum of CS 29491−069, and 18 in HE 1219−0312; in both cases including the Th II 4019 Å line. The heavy-element abundance patterns of these two stars are mostly well-matched to scaled solar residual abundances not formed by the s-process. We also compare the observed pattern with recent high-entropy wind (HEW) calculations, which assume core-collapse supernovae of massive stars as the astrophysical environment for the r-process, and find good agreement for most lanthanides. The abundance ratios of the lighter elements strontium, yttrium, and zirconium, which are presumably not formed by the main r-process, are reproduced well by the model. Radioactive dating for CS 29491−069 with the observed thorium and rare-earth element abundance pairs results in an average age of 9.5 Gyr, when based on solar r-process residuals, and 17.6 Gyr, when using HEW model predictions. Chronometry seems to fail in the case of HE 1219−0312, resulting in a negative age due to its high thorium abundance. HE 1219−0312 could therefore exhibit an overabundance of the heaviest elements, which is sometimes called an "actinide boost".IV

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Improved Laboratory Transition Probabilities for Smiiand Application to the Samarium Abundances of the Sun and Threer‐Process–rich, Metal‐poor Stars

Cited by 121 publications

References 97 publications

Abundance Signatures in Halo Stars: Clues to Nucleosynthesis in the First Stars

Abundance Signatures in Halo Stars: Clues to Nucleosynthesis in the First Stars

Three carbon-enhanced metal-poor dwarf stars from the SDSS

The Hamburg/ESO R-process enhanced star survey (HERES)

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