Determination of Nucleosynthetic Yields of Supernovae and Very Massive Stars from Abundances in Metal‐Poor Stars

(Abridged) We determine the yields of Na to Ni for Type II supernovae (SNeII) and the yield patterns of the same elements for Type Ia supernovae (SNe Ia)and very massive (>100 M_sun) stars (VMS) using a phenomenological model ofstellar nucleosynthesis and the data on a number of stars with -4<[Fe/H]<-3, asingle star with [Fe/H]=-2.04, and the sun. We consider that there are twodistinct kinds of SNe II: the high-frequency SNe II(H) and the low-frequencySNe II(L). We also consider that VMS were the dominant first-generation starsformed from big bang debris. The yield patterns of Na to Ni for SNe II(H),II(L), and Ia and VMS appear to be well defined. It is found that SNe II(H)produce almost none of these elements, that SNe II(L) can account for theentire solar inventory of Na, Mg, Si, Ca, Ti, and V, and that compared with SNeII(L), VMS underproduce Na, Al, V, Cr, and Mn, overproduce Co, but otherwisehave an almost identical yield pattern. A comparison is made between the yieldpatterns determined here from the observational data and those from ab initiomodels of nucleosynthesis in SNe II and VMS. The evolution of the otherelements relative to Fe is shown to involve three distinct stages, the earliestof which is directly related to the problems of early aggregation anddispersion of baryonic matter. It is argued that the VMS contributions shouldrepresent the typical composition of dispersed baryonic matter in the universe.Comment: 33 pages, 14 postscript figures, to appear in Ap