EVIDENCE OF HEAVY ELEMENT NUCLEOSYNTHESIS EARLY IN THE HISTORY OF THEGALAXY - THE ULTRA-METAL-POOR STAR CS-22892-052

We analyze the neutron-capture element (Z > 30) abundance distribution of the ultra-metal-poor (but neutron-capture element rich) halo star CS 22892-052. The observed stellar elemental distribution is compared with those produced by the slow and rapid neutron capture processes (i .e., the s- and r-process) in solar system material. This comparison i ndicates that the elemental abundances, from barium to erbium, in this Galactic halo star, have the same relative proportions as the solar s ystem r-process distribution. Within the uncertainties of the abundanc e determinations, the elements strontium and zirconium, but not yttriu m, also fall on the same scaled solar r-process curve. The main compon ent of the s-process cannot reproduce the observed neutron-capture abu ndances in this star. The weak component of the s-process, expected to occur during core helium burning in massive stars, can fit the relati ve abundance distribution of Sr and Y, but not Zr, suggesting that for the currently observed abundances in CS 22892-052, an admixture of th e weak s- and the r-process might be required for production of the el ements Sr to Zr. These results give evidence of the occurrence of heav y element nucleosynthesis, particularly the r-process, early in the hi story of the Galaxy, and further suggest a generation of massive stars (the astrophysical site for the r-process), preceding the formation o f this very metal poor halo star, that was responsible for producing t he observed heavy elements.