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The Hamburg/ESO R-p...
The Hamburg/ESO R-process Enhanced Star survey (HERES)
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- Hill, V. (författare)
- Univ Cote Azur, Observ Cote Azur, CNRS, Lab Lagrange, Bd Observ,CS 34229, F-06304 Nice 4, France.
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- Christlieb, N. (författare)
- Heidelberg Univ, Zentrum Astron, Konigstuhl 12, D-69117 Heidelberg, Germany.
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- Beers, T. C. (författare)
- Univ Notre Dame, Dept Phys, Notre Dame, IN 46556 USA.;Univ Notre Dame, JINA Ctr Evolut Elements, Notre Dame, IN 46556 USA.
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- Barklem, Paul S. (författare)
- Uppsala universitet,Teoretisk astrofysik
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Kratz, K. -L (författare)
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- Nordstrom, B. (författare)
- Univ Copenhagen, Niels Bohr Inst, Dark Cosmol Ctr, Juliane Maries Vej 30, DK-2100 Copenhagen, Denmark.;Aarhus Univ, Dept Phys & Astron, Stellar Astrophys Ctr, Ny Munkegade 120, DK-8000 Aarhus C, Denmark.
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- Pfeiffer, B. (författare)
- Johannes Gutenberg Univ Mainz, Fachbereich Chem Pharm & Geowissensch, D-55128 Mainz, Germany.
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- Farouqi, K. (författare)
- Max Planck Inst Chem, Otto Hahn Inst, D-55128 Mainz, Germany.;Johannes Gutenberg Univ Mainz, Fachbereich Chem Pharm & Geowissensch, D-55128 Mainz, Germany.
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Univ Cote Azur, Observ Cote Azur, CNRS, Lab Lagrange, Bd Observ,CS 34229, F-06304 Nice 4, France Heidelberg Univ, Zentrum Astron, Konigstuhl 12, D-69117 Heidelberg, Germany. (creator_code:org_t)
- 2017-11-21
- 2017
- Engelska.
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Ingår i: Astronomy and Astrophysics. - : EDP SCIENCES S A. - 0004-6361 .- 1432-0746. ; 607
- Relaterad länk:
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https://www.aanda.or...
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- We report an abundance analysis for the highly r-process-enhanced (r-II) star CS 29497-004, a very metal-poor giant with solar system T-eff = 5013 K and [Fe/H] = -2 : 85, whose nature was initially discovered in the course of the HERES project. Our analysis is based on high signal-to-noise ratio, high-resolution (R similar to 75 000) VLT/UVES spectra and MARCS model atmospheres under the assumption of local thermodynamic equilibrium, and obtains abundance measurements for a total of 46 elements, 31 of which are neutron-capture elements. As is the case for the other similar to 25 r-II stars currently known, the heavy-element abundance pattern of CS 29497-004 well-matches a scaled solar system second peak r-process-element abundance pattern. We confirm our previous detection of Th, and demonstrate that this star does not exhibit an "actinide boost". Uranium is also detected (log is an element of (U) = -2 : 20 +/- 0 : 30), albeit with a large measurement error that hampers its use as a precision cosmo-chronometer. Combining the various elemental chronometer pairs that are available for this star, we derive a mean age of 12 : 2 +/- 3 : 7 Gyr using the theoretical production ratios from published waitingpoint approximation models. We further explore the high-entropy wind model (Farouqi et al. 2010, ApJ, 712, 1359) production ratios arising from different neutron richness of the ejecta (Y-e), and derive an age of 13 : 7 +/- 4 : 4 Gyr for a best-fitting Y-e = 0 : 447. The U/Th nuclei-chronometer is confirmed to be the most resilient to theoretical production ratios and yields an age of 16 : 5 +/- 6 : 6 Gyr. Lead (Pb) is also tentatively detected in CS 29497-004, at a level compatible with a scaled solar r-process, or with the theoretical expectations for a pure r-process in this star.
Ämnesord
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Nyckelord
- stars: abundances
- stars: individual: CS 29497-004
- stars: Population II
- stars: chemically peculiar
- Galaxy: halo
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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