The EMP star SPLUS J142445.34-254247.1 with GHOST

This star was first selected as a metal-poor candidate from its narrowband S-PLUS photometry and followed up spectroscopically in medium resolution with Gemini-South/GMOS, which confirmed its low-metallicity status. High-resolution spectroscopy was gathered with GHOST at Gemini-South, allowing for the determination of the chemical abundances for 36 elements, from carbon to thorium.

At [Fe/H]=-3.39, SPLUS J1424-2542 is one of the lowest-metallicity stars with measured Th and has the highest log{epsilon}(Th/Eu) observed to date, making it part of the "actinide-boost" category of r-process-enhanced stars. The analysis presented here suggests that the gas cloud from which SPLUS_J1424-2542 formed must have been enriched by at least two progenitor populations. The light-element (Z<=30) abundance pattern is consistent with the yields from a supernova explosion of metal-free stars with 11.3-13.4M_{sun}_, and the heavy-element (Z>=38) abundance pattern can be reproduced by the yields from a neutron star merger (1.66M_{sun}_ and 1.27M_{sun}_) event.