The Hamburg/ESO R-process Enhanced Star Survey (HERES) - XI. the highly r-process-enhanced star CS 29497-004
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...
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| Main Authors: | , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
2017
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| In: |
Astronomy and astrophysics
Year: 2017, Volume: 607 |
| ISSN: | 1432-0746 |
| DOI: | 10.1051/0004-6361/201629092 |
| Online Access: | Verlag, kostenfrei, Volltext: http://dx.doi.org/10.1051/0004-6361/201629092 Verlag, kostenfrei, Volltext: https://www.aanda.org/articles/aa/abs/2017/11/aa29092-16/aa29092-16.html 
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| Author Notes: | V. Hill, N. Christlieb, T.C. Beers, P.S. Barklem, K.-L. Kratz, B. Nordström, B. Pfeiffer, and K. Farouqi |
| Summary: | 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 ~ 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 ~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 ϵ (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 waiting-point 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. |
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| Item Description: | Published online: 21 November 2017 Gesehen am 21.06.2018 |
| Physical Description: | Online Resource |
| ISSN: | 1432-0746 |
| DOI: | 10.1051/0004-6361/201629092 |