Sign on

SAO/NASA ADS Astronomy Abstract Service


· Find Similar Abstracts (with default settings below)
· Electronic Refereed Journal Article (HTML)
· Full Refereed Journal Article (PDF/Postscript)
· arXiv e-print (arXiv:0904.3105)
· On-line Data
· References in the article
· Citations to the Article (59) (Citation History)
· Refereed Citations to the Article
· SIMBAD Objects (57)
· Also-Read Articles (Reads History)
·
· Translate This Page
Title:
The End of Nucleosynthesis: Production of Lead and Thorium in the Early Galaxy
Authors:
Roederer, Ian U.; Kratz, Karl-Ludwig; Frebel, Anna; Christlieb, Norbert; Pfeiffer, Bernd; Cowan, John J.; Sneden, Christopher
Affiliation:
AA(Department of Astronomy, University of Texas at Austin, 1 University Station, C1400, Austin, TX 78712-0259, USA ), AB(Max-Planck-Institut für Chemie, Otto-Hahn-Institut, J.-J.-Becherweg 27, D-55128 Mainz, Germany ), AC(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-20, Cambridge, MA 02138, USA ), AD(Zentrum für Astronomie der Universität Heidelberg, Landessternwarte, Königstuhl 12, D-69117 Heidelberg, Germany ), AE(Max-Planck-Institut für Chemie, Otto-Hahn-Institut, J.-J.-Becherweg 27, D-55128 Mainz, Germany ), AF(Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019, USA ), AG(Department of Astronomy, University of Texas at Austin, 1 University Station, C1400, Austin, TX 78712-0259, USA )
Publication:
The Astrophysical Journal, Volume 698, Issue 2, pp. 1963-1980 (2009). (ApJ Homepage)
Publication Date:
06/2009
Origin:
IOP
Astronomy Keywords:
Galaxy: halo, nuclear reactions, nucleosynthesis, abundances, stars: abundances, stars: Population II
DOI:
10.1088/0004-637X/698/2/1963
Bibliographic Code:
2009ApJ...698.1963R

Abstract

We examine the Pb and Th abundances in 27 metal-poor stars (-3.1< [Fe/H] <-1.4) whose very heavy metal (Z > 56) enrichment was produced only by the rapid (r-) nucleosynthesis process. New abundances are derived from Hubble Space Telescope/Space Telescope Imaging Spectrograph, Keck/High Resolution Echelle Spectrograph, and Very Large Telescope/UV-Visual Echelle Spectrograph spectra and combined with other measurements from the literature to form a more complete picture of nucleosynthesis of the heaviest elements produced in the r-process. In all cases, the abundance ratios among the rare earth elements and the third r-process peak elements considered (La, Eu, Er, Hf, and Ir) are constant and equivalent to the scaled solar system r-process abundance distribution. We compare the stellar observations with r-process calculations within the classical "waiting-point" approximation. In these computations a superposition of 15 weighted neutron-density components in the range 23 <=log nn <= 30 is fit to the r-process abundance peaks to successfully reproduce both the stable solar system isotopic distribution and the stable heavy element abundance pattern between Ba and U in low-metallicity stars. Under these astrophysical conditions, which are typical of the "main" r-process, we find very good agreement between the stellar Pb r-process abundances and those predicted by our model. For stars with anomalously high Th/Eu ratios (the so-called actinide boost), our observations demonstrate that any nucleosynthetic deviations from the main r-process affect—at most—only the elements beyond the third r-process peak, namely Pb, Th, and U. Our theoretical calculations also indicate that possible r-process abundance "losses" by nuclear fission are negligible for isotopes along the r-process path between Pb and the long-lived radioactive isotopes of Th and U.
Bibtex entry for this abstract   Preferred format for this abstract (see Preferences)


Find Similar Abstracts:

Use: Authors
Title
Keywords (in text query field)
Abstract Text
Return: Query Results Return    items starting with number
Query Form
Database: Astronomy
Physics
arXiv e-prints