Measurement of the Europium Isotope Ratio for the Extremely Metal poor,r‐Process–enhanced Star CS 31082‐001
- 20 March 2003
- journal article
- Published by American Astronomical Society in The Astrophysical Journal
- Vol. 586 (1) , 506-511
- https://doi.org/10.1086/367540
Abstract
We report the first measurement of the isotope fraction of europium (151Eu and 153Eu) for the extremely metal-poor, r-process-enhanced star CS31082-001, based on high-resolution spectra obtained with the Subaru Telescope High Dispersion Spectrograph. We have also obtained new measurements of this ratio for two similar stars with previous europium isotope measurements, CS22892-052 and HD115444. The measurements were made using observations of the Eu lines in these spectra that are most significantly affected by isotope shifts and hyperfine splitting. The fractions of 151Eu derived for CS31082-001, CS22892-052, and HD115444 are 0.44, 0.51, and 0.46, respectively, with uncertainties of about +/-0.1. CS31082-001, the first star with a meaningful measurement of U outside of the solar system, is known to exhibit peculiar abundance ratios between the actinide and rare-earth elements (e.g., Th/Eu), ratios that are significantly different from those for other stars with large excesses of r-process elements, such as our two comparison objects. Nevertheless, our analysis indicates that the Eu isotope ratio of CS31082-001 agrees, within the errors, with those of other r-process-enhanced objects, and with that of solar-system material.Comment: 16 pages, 4 figures, Apj, in presKeywords
All Related Versions
This publication has 20 references indexed in Scilit:
- High Dispersion Spectrograph (HDS) for the Subaru TelescopePublications of the Astronomical Society of Japan, 2002
- Chemical Composition of Carbon-Rich, Very Metal-Poor Subgiant LP 625-44 Observed with the Subaru/HDSPublications of the Astronomical Society of Japan, 2002
- First stars. I. The extremer-element rich, iron-poor halo giant CS 31082-001Astronomy & Astrophysics, 2002
- Improved Laboratory Transition Parameters for Euiiand Application to the Solar Europium Elemental and Isotopic CompositionThe Astrophysical Journal, 2001
- The Incidence of Binaries among Very Metal-poor Carbon StarsThe Astronomical Journal, 2001
- Measurement of stellar age from uranium decayNature, 2001
- General Relativistic Effects on Neutrino‐driven Winds from Young, Hot Neutron Stars andr‐Process NucleosynthesisThe Astrophysical Journal, 2000
- Neutron Capture in Low‐Mass Asymptotic Giant Branch Stars: Cross Sections and Abundance SignaturesThe Astrophysical Journal, 1999
- Nucleosynthesis in Neutrino‐driven Winds. II. Implications for Heavy Element SynthesisThe Astrophysical Journal, 1997
- Abundances of the elements: Meteoritic and solarGeochimica et Cosmochimica Acta, 1989