Accurate Wavelengths, Oscillator Strengths and Hyperfine Structure in Selected Praseodymium Lines of Astrophysical Interest

Ivarsson, Stefan; Litzén, Ulf; Wahlgren, G. M.

doi:10.1238/physica.regular.064a00455

Cited by 57 publications

(49 citation statements)

References 26 publications

(41 reference statements)

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“…For the cerium abundance analysis we adopted the line list from Lawler et al (2009). The praseodymium abundance was derived using line lists from Li et al (2007) and Ivarsson et al (2001). Since the lines are relatively weak, we ignored any 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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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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“…Fortunately, most neutron-capture element species considered here have been subjected to extensive laboratory investigations within the past two decades (Biémont et al 1998;Den Hartog et al 2003, 2006Ivarsson et al 2001Ivarsson et al , 2003Lawler et al 2001aLawler et al ,b,c, 2004Lawler et al , 2006Lawler et al , 2007Lawler et al , 2008Lawler et al , 2009Ljung et al 2006;Nilsson et al 2002;Wickliffe et al 2000;Xu et al 2006). We employed g f −values determined by these laboratory efforts.…”

Section: Line Selection and Atomic Datamentioning

confidence: 99%

The Hamburg/ESOR-process enhanced star survey (HERES)

Mashonkina

Christlieb

Barklem

et al. 2010

A&A

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AstrophysicsThe Hamburg/ESO R-process enhanced star survey (HERES) V ABSTRACTAims. We present a detailed abundance analysis of a strongly r-process enhanced giant star discovered in the HERES project, HE 2327−5642, for which [Fe/H] = −2.78, [r/Fe] = +0.99. Methods. We determined the stellar parameters and element abundances by analyzing the high-quality VLT/UVES spectra. The surface gravity was calculated from the non-local thermodynamic equilibrium (NLTE) ionization balance between Fe i and Fe ii, and Ca i and Ca ii.Results. Accurate abundances for a total of 40 elements and for 23 neutron-capture elements beyond Sr and up to Th were determined in HE 2327−5642. For every chemical species, the dispersion in the single line measurements around the mean does not exceed 0.11 dex. The heavy element abundance pattern of HE 2327−5642 is in excellent agreement with those previously derived for other strongly r-process enhanced stars, such as CS 22892-052, CS 31082-001, and HE 1219-0312. Elements in the range from Ba to Hf match the scaled Solar r-process pattern very well. No firm conclusion can be drawn about the relationship between the fisrt neutroncapture peak elements, Sr to Pd, in HE 2327−5642 and the Solar r-process, due to the uncertainty in the Solar r-process. A clear distinction in Sr/Eu abundance ratios was found between the halo stars of different europium enhancement. The strongly r-process enhanced stars contain a low Sr/Eu abundance ratio at [Sr/Eu] = −0.92 ± 0.13, while the stars with 0 < [Eu/Fe] < 1 and [Eu/Fe] < 0 have 0.36 dex and 0.93 dex higher Sr/Eu values, respectively. Radioactive dating for HE 2327−5642 with the observed thorium and rare-earth element abundance pairs results in an average age of 13.3 Gyr, when based on the high-entropy wind calculations, and 5.9 Gyr, when using the Solar r-residuals. We propose that HE 2327−5642 is a radial-velocity variable based on our high-resolution spectra covering ∼4.3 years.

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“…Further constants were taken from Holt et al (1999) for Mn II (g f -values from Martinson et al 1977), Rutten (1978) compiled data for Ba, Lawler et al (2001a) give measurements for La, Ivarsson et al (2001) for Pr, and Lawler et al (2001bLawler et al ( , 2004 for Eu and Ho. Molecular line data for four different species (CH, NH, OH and CN) were assembled for the abundance measurements of the CNO elements.…”

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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Accurate Wavelengths, Oscillator Strengths and Hyperfine Structure in Selected Praseodymium Lines of Astrophysical Interest

Cited by 57 publications

References 26 publications

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

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

The Hamburg/ESOR-process enhanced star survey (HERES)

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

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