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Lead abundance in the uranium star CS 31082-001

Plez, B.; Hill, V.; Cayrel, R.; Spite, M.; Barbuy, B.; Beers, T. C.; Bonifacio, P.; Primas, F. and Nordström, Birgitta LU (2004) In Astronomy & Astrophysics 428(1). p.9-12
Abstract
In a previous paper we were able to measure the abundance of uranium andthorium in the very-metal poor halo giant BPS <ASTROBJ>CS31082-001</ASTROBJ>, but only obtained an upper limit for the abundanceof lead (Pb). We have got from ESO 17 h of additional exposure on thisstar in order to secure a detection of the minimum amount of leadexpected to be present in <ASTROBJ>CS 31082-001</ASTROBJ>, the amountarising from the decay of the original content of Th and U in the star.We report here this successful detection. We find an LTE abundancelog(Pb/H)+12=-0.55 ± 0.15 dex, one dex below the upper limitsgiven by other authors for the similar stars <ASTROBJ>CS22892-052</ASTROBJ> and <ASTROBJ>BD... (More)
In a previous paper we were able to measure the abundance of uranium andthorium in the very-metal poor halo giant BPS <ASTROBJ>CS31082-001</ASTROBJ>, but only obtained an upper limit for the abundanceof lead (Pb). We have got from ESO 17 h of additional exposure on thisstar in order to secure a detection of the minimum amount of leadexpected to be present in <ASTROBJ>CS 31082-001</ASTROBJ>, the amountarising from the decay of the original content of Th and U in the star.We report here this successful detection. We find an LTE abundancelog(Pb/H)+12=-0.55 ± 0.15 dex, one dex below the upper limitsgiven by other authors for the similar stars <ASTROBJ>CS22892-052</ASTROBJ> and <ASTROBJ>BD +17°3248</ASTROBJ>, alsoenhanced in r-process elements. From the observed present abundances ofTh and U in the star, the expected amount of Pb produced by the decay of<SUP>232</SUP>Th, and <SUP>238</SUP>U alone, over 12-15 Gyr is-0.73± 0.17 dex. The decay of <SUP>235</SUP>U is more difficultto estimate, but is probably slightly below the contribution of<SUP>238</SUP>U, making the contribution of the 3 actinides onlyslightly below, or even equal to, the measured abundance. Thecontribution from the decay of <SUP>234</SUP>U has was not included, forlack of published data. In this sense our determination is a lower limitto the contribution of actinides to lead production. We comment thisresult, and we note that if a NLTE analysis, not yet possible, doublesour observed abundance, the decay of the 3 actinides will stillrepresent 50 per cent of the total lead, a proportion higher than thevalues considered so far in the literature.Based on observations obtained with the Very Large Telescope of theEuropean Southern Observatory at Paranal, Chile. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
atomic data, abundances, nucleosynthesis, stars: abundances, physical data and processes: nuclear reactions
in
Astronomy & Astrophysics
volume
428
issue
1
pages
9 - 12
publisher
EDP Sciences
external identifiers
  • wos:000225334900003
  • scopus:10044267935
ISSN
0004-6361
DOI
10.1051/0004-6361:200400094
language
English
LU publication?
yes
id
cd636aef-4a22-4891-b528-7093e17f0c9d (old id 134128)
date added to LUP
2007-07-13 15:02:03
date last changed
2017-12-10 04:35:35
@article{cd636aef-4a22-4891-b528-7093e17f0c9d,
  abstract     = {In a previous paper we were able to measure the abundance of uranium andthorium in the very-metal poor halo giant BPS &lt;ASTROBJ&gt;CS31082-001&lt;/ASTROBJ&gt;, but only obtained an upper limit for the abundanceof lead (Pb). We have got from ESO 17 h of additional exposure on thisstar in order to secure a detection of the minimum amount of leadexpected to be present in &lt;ASTROBJ&gt;CS 31082-001&lt;/ASTROBJ&gt;, the amountarising from the decay of the original content of Th and U in the star.We report here this successful detection. We find an LTE abundancelog(Pb/H)+12=-0.55 ± 0.15 dex, one dex below the upper limitsgiven by other authors for the similar stars &lt;ASTROBJ&gt;CS22892-052&lt;/ASTROBJ&gt; and &lt;ASTROBJ&gt;BD +17°3248&lt;/ASTROBJ&gt;, alsoenhanced in r-process elements. From the observed present abundances ofTh and U in the star, the expected amount of Pb produced by the decay of&lt;SUP&gt;232&lt;/SUP&gt;Th, and &lt;SUP&gt;238&lt;/SUP&gt;U alone, over 12-15 Gyr is-0.73± 0.17 dex. The decay of &lt;SUP&gt;235&lt;/SUP&gt;U is more difficultto estimate, but is probably slightly below the contribution of&lt;SUP&gt;238&lt;/SUP&gt;U, making the contribution of the 3 actinides onlyslightly below, or even equal to, the measured abundance. Thecontribution from the decay of &lt;SUP&gt;234&lt;/SUP&gt;U has was not included, forlack of published data. In this sense our determination is a lower limitto the contribution of actinides to lead production. We comment thisresult, and we note that if a NLTE analysis, not yet possible, doublesour observed abundance, the decay of the 3 actinides will stillrepresent 50 per cent of the total lead, a proportion higher than thevalues considered so far in the literature.Based on observations obtained with the Very Large Telescope of theEuropean Southern Observatory at Paranal, Chile.},
  author       = {Plez, B. and Hill, V. and Cayrel, R. and Spite, M. and Barbuy, B. and Beers, T. C. and Bonifacio, P. and Primas, F. and Nordström, Birgitta},
  issn         = {0004-6361},
  keyword      = {atomic data,abundances,nucleosynthesis,stars: abundances,physical data and processes: nuclear reactions},
  language     = {eng},
  number       = {1},
  pages        = {9--12},
  publisher    = {EDP Sciences},
  series       = {Astronomy & Astrophysics},
  title        = {Lead abundance in the uranium star CS 31082-001},
  url          = {http://dx.doi.org/10.1051/0004-6361:200400094},
  volume       = {428},
  year         = {2004},
}