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The Hamburg/ESO R-p...
The Hamburg/ESO R-process Enhanced Star survey (HERES). I. Project description, and discovery of two stars with strong enhancements of neutron-capture elements
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Christlieb, N. (author)
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Beers, T. C. (author)
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Barklem, P. S. (author)
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Bessell, M. (author)
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Hill, V. (author)
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Holmberg, J. (author)
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Korn, A. J. (author)
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Marsteller, B. (author)
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Mashonkina, L. (author)
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Qian, Y.-Z. (author)
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Rossi, S. (author)
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Wasserburg, G. J. (author)
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Zickgraf, F.-J. (author)
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Kratz, K.-L. (author)
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- Nordström, Birgitta (author)
- Lund University,Lunds universitet,Astronomi - Genomgår omorganisation,Institutionen för astronomi och teoretisk fysik - Genomgår omorganisation,Naturvetenskapliga fakulteten,Lund Observatory - Undergoing reorganization,Department of Astronomy and Theoretical Physics - Undergoing reorganization,Faculty of Science
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Pfeiffer, B. (author)
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Rhee, J. (author)
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Ryan, S. G. (author)
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(creator_code:org_t)
- 2004-12-07
- 2004
- English.
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In: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 428:3, s. 1027-1037
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Abstract
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- We report on a dedicated effort to identify and study metal-poor stars strongly enhanced in r-process elements ([r/Fe]>1 dex; hereafter r-IIstars), the Hamburg/ESO R-process Enhanced Star survey (HERES).Moderate-resolution (∼2 Å) follow-up spectroscopy has been obtained for metal-poor giant candidates selected from the Hamburg/ESO objective-prism survey (HES) as well as the HK survey to identify sharp-lined stars with [Fe/H]<-2.5 dex. For several hundred confirmed metal-poor giants brighter than B∼ 16.5 mag (most of them from theHES), ``snapshot'' spectra (R∼ 20 000; S/N ∼ 30 per pixel) are being obtained with VLT/UVES, with the main aim of finding the 2-3% r-II stars expected to be among them. These are studied in detail by means of higher resolution and higher S/N spectra. In this paper we describe a pilot study based on a set of 35 stars, including 23 from the HK survey,eight from the HES, and four comparison stars. We discovered two new r-II stars, CS 29497-004 ([Eu/Fe]=1.64± 0.22) and CS 29491-069([Eu/Fe]=1.08± 0.23). A first abundance analysis of CS 29497-004 yields that its abundances of Ba to Dy are on average enhanced by 1.5 dex with respect to iron and the Sun and match a scaled solar r-process pattern well, while Th is underabundant relative to that pattern by 0.3dex, which we attribute to radioactive decay. That is, CS 29497-004 seems not to belong to the class of r-process enhanced stars displaying an ``actinide boost'', like CS 31082-001 (Hill et al. 2002), or CS30306-132 (Honda et al. 2004b). The abundance pattern agrees well with predictions of the phenomenological model of Qian & Wasserburg.Based in large part on observations collected at the European Southern Observatory, Paranal, Chile (proposal number 68.B-0320).}
Subject headings
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Keyword
- surveys
- stars: abundances
- stars: population II
- Galaxy: abundances
- Galaxy: halo
Publication and Content Type
- art (subject category)
- ref (subject category)
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- By the author/editor
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Christlieb, N.
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Beers, T. C.
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Barklem, P. S.
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Bessell, M.
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Hill, V.
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Holmberg, J.
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show more...
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Korn, A. J.
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Marsteller, B.
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Mashonkina, L.
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Qian, Y.-Z.
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Rossi, S.
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Wasserburg, G. J ...
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Zickgraf, F.-J.
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Kratz, K.-L.
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Nordström, Birgi ...
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Pfeiffer, B.
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Rhee, J.
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Ryan, S. G.
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show less...
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- NATURAL SCIENCES
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Lund University