Bochum 1998 – scientific programme
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HK: Hadronen und Kerne
HK 53: Nuclear Astrophysics IV
HK 53.3: Talk
Wednesday, March 18, 1998, 14:45–15:00, G
R-Process Abundances and Cosmochronometers in Old Metal-Poor Halo Stars ∗ — •B. Pfeiffer1, K.-L. Kratz1, F.-K. Thielemann2, and J.J. Cowan3 — 1Inst. für Kernchemie, Universität Mainz, Germany — 2Inst. für Theoretische Physik, Universität Basel, Switzerland — 3Department of Physics and Astronomy, University of Oklahoma, USA
Recently, stellar abundances of neutron-capture elements (beyond iron) have been determined over a wide z-range in 4 very metal-poor Galactic halo stars using the GHR Spectrograph of the Hubble Telescope [1]. After adjustment to solar metallicity, the values for these first-generation stars are consistent with the global solar-system r-process abundances as well as with our recent ETFSI-Q predictions [2,3]. This agreement not only indicates a unique r-process scenario (at least beyond Z≃50), but also allows to make reliable extrapolations of the long-lived actinide cosmochronometers. With the measured Th and U abundances in the halo stars and our calculated values, lower limits for the decay age of the Galaxy can be derived independent of chemical-evolution models.
[1] C. Sneden et al., Ap.J. 467, 819 (1996), and Ap.J. in press
[2] B. Pfeiffer et al., Z. Phys. A357, 235 (1997)
[3] K.-L. Kratz et al., Proc. NN’97, Nucl. Phys. A, in press ∗ work supported by BMBF (06MZ465)