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SPLUS J142445.34–254247.1: An r-process–enhanced, Actinide-boost, Extremely Metal-poor Star Observed with GHOST
- Source :
- The Astrophysical Journal, Vol 959, Iss 1, p 60 (2023)
- Publication Year :
- 2023
- Publisher :
- IOP Publishing, 2023.
-
Abstract
- We report on a chemo-dynamical analysis of SPLUS J142445.34−254247.1 (SPLUS J1424−2542), an extremely metal-poor halo star enhanced in elements formed by the rapid neutron-capture process ( r -process). 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 $\mathrm{log}\epsilon (\mathrm{Th}/\mathrm{Eu})$ 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 11.3–13.4 M _⊙ , and the heavy-element ( Z ≥ 38) abundance pattern can be reproduced by the yields from a neutron star merger (1.66 M _⊙ and 1.27 M _⊙ ) event. A kinematical analysis also reveals that SPLUS J1424−2542 is a low-mass, old halo star with a likely in situ origin, not associated with any known early merger events in the Milky Way.
Details
- Language :
- English
- ISSN :
- 15384357
- Volume :
- 959
- Issue :
- 1
- Database :
- Directory of Open Access Journals
- Journal :
- The Astrophysical Journal
- Publication Type :
- Academic Journal
- Accession number :
- edsdoj.253f5ad355e48d783e9c8f4b24f320a
- Document Type :
- article
- Full Text :
- https://doi.org/10.3847/1538-4357/ad077e