2004A&A...428L...9P -
Astronomy and Astrophysics, volume 428, L9-12 (2004/12-2)
Lead abundance in the uranium star CS31082-001.
PLEZ B., HILL V., CAYREL R., SPITE M., BARBUY B., BEERS T.C., BONIFACIO P., PRIMAS F. and NORDSTROEM B.
Abstract (from CDS):
In a previous paper we were able to measure the abundance of uranium and thorium in the very-metal poor halo giant BPS
CS31082-001, but only obtained an upper limit for the abundance of lead (Pb). We have got from ESO 17 h of additional exposure on this star in order to secure a detection of the minimum amount of lead expected to be present in
CS31082-001, the amount arising from the decay of the original content of Th and U in the star. We report here this successful detection. We find an LTE abundance log(Pb/H)+12=-0.55±0.15dex, one dex below the upper limits given by other authors for the similar stars
CS22892-052 and
BD+17°3248, also enhanced in r-process elements. From the observed present abundances of Th and U in the star, the expected amount of Pb produced by the decay of
232Th, and
238U alone, over 12-15Gyr is -0.73±0.17dex. The decay of
235U is more difficult to estimate, but is probably slightly below the contribution of
238U, making the contribution of the 3 actinides only slightly below, or even equal to, the measured abundance. The contribution from the decay of
234U has was not included, for lack of published data. In this sense our determination is a lower limit to the contribution of actinides to lead production. We comment this result, and we note that if a NLTE analysis, not yet possible, doubles our observed abundance, the decay of the 3 actinides will still represent 50 per cent of the total lead, a proportion higher than the values considered so far in the literature.
Abstract Copyright:
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Journal keyword(s):
stars: abundances - physical data and processes: nuclear reactions, nucleosynthesis, abundances - atomic data
Simbad objects:
4
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