2002/11/28 by Wako Aoki, W. Aoki, Satoshi Honda +4 · 44 citations
Chemistry · Physics and Astronomy · #Analytical Chemistry (journal) #Astro and Planetary Science #Astronomy #Astrophysics #Chemistry #Europium #Hyperfine structure #Ion #Isotope #Metal #Nuclear physics #Nuclear physics research studies #Nucleosynthesis #Physics #Spectral line #Spectrograph #Stars #Stellar, planetary, and galactic studies #astro-ph #r-process #s-process
paper · pdf · doi:10.1086/367540
published in The Astrophysical Journal 586(1), 506-511 (IOP Publishing) · 16 pages, 4 figures, Apj, in press
arxiv created 2002/11/28 · openalex publication_date 2003/03/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
We report the first measurement of the isotope fraction of europium ( 151 Eu and 153 Eu) for the extremely metal poor, r -process-enhanced star CS 31082-001, 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, CS 22892-052 and HD 115444. 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 151 Eu derived for CS 31082-001, CS 22892-052, and HD 115444 are 0.44, 0.51, and 0.46, respectively, with uncertainties of about ±0.1. CS 31082-001, 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 CS 31082-001 agrees, within the errors, with those of other r -process-enhanced objects and with that of solar system material.