Origin of LAMOST J1010+2358 Revisited

Abstract

Signature from Pop III massive stars of $140$--$260\,{\rm M_\odot}$ that end their lives as pair-instability supernovae (PISNe) are expected to be seen in very metal-poor (VMP) stars of ${\rm [Fe/H]}\leq -2$. Although thousands of VMP stars have been discovered, the identification of a VMP star with a PISN signature has been elusive. Recently, the VMP star LAMOST J1010+2358 was claimed to be the first star with a clear PISN signature. A subsequent study showed that ejecta from low-mass core-collapse supernovae (CCSNe) can also fit the abundance pattern equally well and additional elements such as C and Al are required to differentiate the two sources. Follow-up observations of LAMOST J1010+2358 by two independent groups were able to detect both C and Al. Additionally, key odd elements such as Na and Sc were also detected whose abundances were found to be higher than the upper limits found in the original detection. We perform a detailed analysis of the newly observed abundance patterns by exploring various possible formation channels for VMP stars. We find that purely low-mass CCSN ejecta as well as the combination of CCSN and Type 1a SN ejecta can provide an excellent fit to the newly observed abundance pattern. Our results confirm earlier analysis that the newly observed abundance pattern is peculiar but has no signatures of PISN.