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ABSTRACT Low-metallicity very massive stars with an initial mass of ∼140–$$260\, \mathrm{M}_\odot$$ are expected to end their lives as pair-instability supernovae (PISNe). The abundance pattern resulting from a PISN differs drastically from regular core-collapse supernova (CCSN) models and is expected to be seen in very metal-poor (VMP) stars of [Fe/H] ≲ −2. Despite the routine discovery of many VMP stars, the unique abundance pattern expected from PISNe has not been unambiguously detected. The recently discovered VMP star LAMOST J1010 + 2358, however, shows a peculiar abundance pattern that is remarkably well fit by a PISN, indicating the potential first discovery of a bonafide star born from gas polluted by a PISN. In this paper, we study the detailed nucleosynthesis in a large set of models of CCSN of Pop III and Pop II star of metallicity [Fe/H] = −3 with masses ranging from 12 to $$30\, \mathrm{M}_\odot$$. We find that the observed abundance pattern in LAMOST J1010 + 2358 can be fit at least equally well by CCSN models of ∼12–$$14\, \mathrm{M}_\odot$$ that undergo negligible fallback following the explosion. The best-fitting CCSN models provide a fit that is even marginally better than the best-fitting PISN model. We conclude the measured abundance pattern in LAMOST J1010 + 2358 could have originated from a CCSN and therefore cannot be unambiguously identified with a PISN given the set of elements measured in it to date. We identify key elements that need to be measured in future detections in stars like LAMOST J1010 + 2358 that can differentiate between CCSN and PISN origin. 

ABSTRACT Very metal-poor stars that have [Fe/H] < −2 and that are enhanced in C relative to Fe ([C/Fe] > +0.7) but have no enhancement of heavy elements ([Ba/Fe] < 0) are known as carbon-enhanced metal-poor (CEMP-no) stars. These stars are thought to be produced from a gas that was polluted by the supernova (SN) ejecta of the very first generation (Population III) massive stars. The very high enrichment of C (A(C) ≳ 6) observed in many of the CEMP-no stars is difficult to explain by current models of SN explosions from massive Population III stars when a reasonable dilution of the SN ejecta, which is consistent with detailed simulation of metal mixing in minihaloes, is adopted. We explore rapidly rotating Population III stars that undergo efficient mixing and reach a quasi-chemically homogeneous (QCH) state. We find that QCH stars can eject large amounts of C in the wind and that the resulting dilution of the wind ejecta in the interstellar medium can lead to a C enrichment of A(C) ≲ 7.75. The core of QCH stars can produce up to an order of magnitude of more C than non-rotating progenitors of similar mass and the resulting SN can lead to a C enrichment of A(C) ≲ 7. Our rapidly rotating massive Population III stars cover almost the entire range of A(C) observed in CEMP-no stars and are a promising site for explaining the high C enhancement in the early Galaxy. Our work indicates that a substantial fraction of Population III stars were likely rapid rotators.