A new high resolution very high signal to noise spectrum has been obtained for the metal-poor giant star HD 115444, first examined in detail by Griffin et al. (1982, MNRAS, 198, 637). Our new spectrum was gathered with the High-Resolution Echelle Spectrometer of the McDonald Observatory 2.7m Telescope. We have performed a model atmosphere analysis and line identification, emphasizing the neutron-capture elements; 20 elements with Z>30 have been identified in the HD 115444 spectrum. The overall metallicity was found to be [Fe/H] = --3.0. The abundances of the light and iron-peak elements show the same pattern as other very metal-poor stars (e.g. overdeficiencies of Mn and Cr, overabundances of Co). The initial synthetic spectrum analyses reveal substantial overabundances of all neutron-capture elements with Z>=56 (Ba and beyond). Moreover, the abundance pattern is clearly consistent with production dominated by r-process nucleosynthesis (with little contribution from the s-process), just like that also found in the metal-poor giant star CS 22892-052 (Sneden et al., 1996, ApJ, 467, 819). To illustrate this, in HD 115444 we find [Ba/Eu] = --0.73, while in CS 22892-052, this ratio is --0.79. Thus HD 115444 becomes the second clear example of a very metal-poor yet r-process-rich halo giant. With (for example) [Eu/Fe] =~ +0.9, HD 115444 is a moderate version of CS 22892-052 (which has [Eu/Fe] =~ +1.7).
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 1998