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First stars IV. CS 29497-030: Evidence for operation of the s-process at very low metallicity

Sivarani, T.; Bonifacio, P.; Molaro, P.; Cayrel, R.; Spite, M.; Spite, F.; Plez, B.; Andersen, J.; Barbuy, B. and Beers, T. C., et al. (2004) In Astronomy & Astrophysics 413(3). p.65-1073
Abstract
We present an abundance analysis of the very metal-poor, carbon-enhancedstar CS 29497-030. Our results indicate that this unusually hot turnoffstar (T<SUB>eff</SUB> = 6650 K, log g = 3.5) has a metallicity [Fe/H] =-2.8, and exhibits large overabundances of carbon ([C/Fe] = +2.38),nitrogen ([N/Fe] = +1.88), and oxygen ([O/Fe] = +1.67). This star alsoexhibits a large enhancement in its neutron-capture elements; thepattern follows that expected to arise from the s-process. Inparticular, the Pb abundance is found to be very high with respect toiron ([Pb/Fe] = +3.5), and also with respect to the second peaks-process elements (e.g., Ba, La, Ce, Nd), which fits into the newlyintroduced classification of lead (Pb) stars. The known... (More)
We present an abundance analysis of the very metal-poor, carbon-enhancedstar CS 29497-030. Our results indicate that this unusually hot turnoffstar (T<SUB>eff</SUB> = 6650 K, log g = 3.5) has a metallicity [Fe/H] =-2.8, and exhibits large overabundances of carbon ([C/Fe] = +2.38),nitrogen ([N/Fe] = +1.88), and oxygen ([O/Fe] = +1.67). This star alsoexhibits a large enhancement in its neutron-capture elements; thepattern follows that expected to arise from the s-process. Inparticular, the Pb abundance is found to be very high with respect toiron ([Pb/Fe] = +3.5), and also with respect to the second peaks-process elements (e.g., Ba, La, Ce, Nd), which fits into the newlyintroduced classification of lead (Pb) stars. The known spectroscopicbinary status of this star, along with the observed s-process abundancepattern, suggest that it has accreted matter from a companion, whichformerly was an Asymptotic Giant-Branch (AGB) star. In a preliminaryanalysis, we have also identified broad absorption lines of metallicspecies that suggest a large axial rotational velocity for this star,which may be the result of spin-up associated with the accretion ofmaterial from its previous AGB companion. In addition, this star isclearly depleted in the light element Li. When considered along with itsrather high inferred temperature, these observations are consistent withthe expected properties of a very low metallicity halo blue straggler.Based on observations made with the ESO Very Large Telescope at ParanalObservatory, Chile (program ID 165.N-0276(A)).Table

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keywords
nuclear reactions, nucleosynthesis, abundances, stars: abundances, stars: binary: spectroscopic, stars: individual: CS29497-030, Galaxy: halo, Galaxy: abundances
in
Astronomy & Astrophysics
volume
413
issue
3
pages
65 - 1073
publisher
EDP Sciences
external identifiers
  • wos:000187887900031
  • scopus:10744222770
ISSN
0004-6361
DOI
10.1051/0004-6361:20031590
language
English
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yes
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9e5ca5b5-f8cf-457b-8e4a-e1d1325d3bdf (old id 134197)
date added to LUP
2007-07-20 12:52:41
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2017-12-10 04:34:03
@article{9e5ca5b5-f8cf-457b-8e4a-e1d1325d3bdf,
  abstract     = {We present an abundance analysis of the very metal-poor, carbon-enhancedstar CS 29497-030. Our results indicate that this unusually hot turnoffstar (T&lt;SUB&gt;eff&lt;/SUB&gt; = 6650 K, log g = 3.5) has a metallicity [Fe/H] =-2.8, and exhibits large overabundances of carbon ([C/Fe] = +2.38),nitrogen ([N/Fe] = +1.88), and oxygen ([O/Fe] = +1.67). This star alsoexhibits a large enhancement in its neutron-capture elements; thepattern follows that expected to arise from the s-process. Inparticular, the Pb abundance is found to be very high with respect toiron ([Pb/Fe] = +3.5), and also with respect to the second peaks-process elements (e.g., Ba, La, Ce, Nd), which fits into the newlyintroduced classification of lead (Pb) stars. The known spectroscopicbinary status of this star, along with the observed s-process abundancepattern, suggest that it has accreted matter from a companion, whichformerly was an Asymptotic Giant-Branch (AGB) star. In a preliminaryanalysis, we have also identified broad absorption lines of metallicspecies that suggest a large axial rotational velocity for this star,which may be the result of spin-up associated with the accretion ofmaterial from its previous AGB companion. In addition, this star isclearly depleted in the light element Li. When considered along with itsrather high inferred temperature, these observations are consistent withthe expected properties of a very low metallicity halo blue straggler.Based on observations made with the ESO Very Large Telescope at ParanalObservatory, Chile (program ID 165.N-0276(A)).Table <br/><br>
ef{tab6} is only available in electronic form athttp://www.edpsciences.org},
  author       = {Sivarani, T. and Bonifacio, P. and Molaro, P. and Cayrel, R. and Spite, M. and Spite, F. and Plez, B. and Andersen, J. and Barbuy, B. and Beers, T. C. and Depagne, E. and Hill, V. and François, P. and Nordström, Birgitta and Primas, F.},
  issn         = {0004-6361},
  keyword      = {nuclear reactions,nucleosynthesis,abundances,stars: abundances,stars: binary: spectroscopic,stars: individual: CS29497-030,Galaxy: halo,Galaxy: abundances},
  language     = {eng},
  number       = {3},
  pages        = {65--1073},
  publisher    = {EDP Sciences},
  series       = {Astronomy & Astrophysics},
  title        = {First stars IV. CS 29497-030: Evidence for operation of the s-process at very low metallicity},
  url          = {http://dx.doi.org/10.1051/0004-6361:20031590},
  volume       = {413},
  year         = {2004},
}