出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：We report on new abundance determinations for the neutron-capture elements Cd I (Z=48), Lu II (Z = 71) and Os II (Z = 76) in the r-process enriched star BD + 17 3248. These abundances are derived from an ultraviolet spectrum obtained with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. These are the first detections of these elements in metal-poor r-process enriched halo stars. In addition to the HST observations we have obtained new abundance measurements of the elements Mo I, Ru I and Rh I, based upon High Resolution Echelle Spectrograph observations with Keck. Combining these and previous observations, we have now detected 32 n-capture elements in BD +17 3248 - this is the most of any metal-poor halo star to date. The lighter n-capture elements (38 ≤ Z ≤ 48) appear to show a pronounced odd-even effect. New Hf I abundances from transitions in the UV were also derived and they were lower than previous values based upon optical transitions. The new Hf abundance agrees better with the scaled Solar system r-process distribution. We also derive an age for this star based upon the Th II/Os II chronometer, which is in better agreement with the age derived from other chronometers than the age derived using Th II/Os I.
