Nucleosynthesis in Type II supernovae and the abundances in metal-poor stars

Takayoshi Nakamura, Hideyuki Umeda, Ken'ichi Nomoto, Friedrich Karl Thielemann, Adam S. Burrows

Research output: Contribution to journalArticlepeer-review

99 Scopus citations


We explore the effects on nucleosynthesis in Type II supernovae of various parameters (mass cut, neutron excess, explosion energy, progenitor mass) in order to explain the observed trends of the iron-peak element abundance ratios ([Cr/Fe], [Mn/Fe], [Co/Fe], and [Ni/Fe]) in halo stars as a function of metallicity for the range -4 ≤ [Fe/H] ≤ -2.5. [Cr/Fe] and [Mn/Fe] decrease with decreasing [Fe/H], whereas [Co/Fe] increases. We show that such behavior can be explained by a variation of mass cuts in Type II supernovae as a function of progenitor mass, which provides a changing mix of nucleosynthesis from an alpha-rich freeze-out of Si burning and incomplete Si burning. This explanation is consistent with the amount of ejected 56Ni determined from modeling the early light curves of individual supernovae. We also suggest that the ratio [H/Fe] of halo stars is mainly determined by the mass of interstellar hydrogen mixed with the ejecta of a single supernova, which is larger for larger explosion energy and the larger Strömgren radius of the progenitor.

Original languageEnglish (US)
Pages (from-to)193-208
Number of pages16
JournalAstrophysical Journal
Issue number1 PART 1
StatePublished - May 20 1999

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Galaxy: halo
  • Stars: abundances
  • Supernovae: general


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