A Model for Abundances in Metal‐poor Stars

It is argued that the abundances of r-process related elements in stars with-3<[Fe/H]<-1 can be explained by the contributions of three sources. Thesources are: the first generations of very massive (>100 solar masses) starsthat are formed from Big Bang debris and are distinct from SNII, and two typesof SNII, the H and L events, which can occur only at [Fe/H]>-3. The H eventsare of high frequency and produce dominantly heavy (A>130) r-elements but no Fe(presumably leaving behind black holes). The L events are of low frequency andproduce Fe and dominantly light (A<130) r-elements (essentially none above Ba).By using the observed abundances in two ultra-metal-poor stars and the solarr-abundances, the initial or prompt inventory of elements produced by the firstgenerations of very massive stars and the yields of H and L events can bedetermined. The abundances of a large number of elements in a star can then becalculated from the model by using only the observed Eu and Fe abundances. Tomatch the model results and the observational data for stars with -3<[Fe/H]<-1requires that the solar r-abundances for Sr, Y, Zr, and Ba must besignificantly increased from the standard values. Whether the solarr-components of these elements used here to obtain a fit to the stellar datacan be reconciled with those obtained from solar abundances by subtracting thes-components calculated from models is not clear.Comment: 47 pages, 19 figures, to appear in Ap