J/ApJ/959/60ivo://CDS.VizieR/J/ApJ/959/60doi:10.26093/cds/vizier/ba-xz-1wCDSPlacco V.M.Almeida-Fernandes F.Holmbeck E.M.Roederer I.U.,Mardini M.K.Hayes C.R.Venn K.Chiboucas K.Deibert E.Gamen R.,Heo J.-E.Jeong M.Kalari V.Martioli E.Xu S.Diaz R.,Gomez-Jimenez M.Henderson D.Prado P.Quiroz C.Ruiz-Carmona R.,Simpson C.Urrutia C.McConnachie A.W.Pazder J.Burley G.,Ireland M.Waller F.Berg T.A.M.Robertson J.G.Hartman Z.,Jones D.O.Labrie K.Perez G.Ridgway S.Thomas-Osip J.2026-03-02T20:03:10Z2026-02-24T07:42:49ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frvisible-astronomyspectroscopyline-intensitieschemically-peculiar-starschemical-abundanceshalo-starsWe 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 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. 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.2023ApJ...959...60Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/959/60CatalogResearchIsServedByTAP VizieR generic servicerelated-toII/358 : SkyMapper Southern Sky Survey. DR1.1 (Wolf+, 2018)I/350 : Gaia EDR3 (Gaia Collaboration, 2020)I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)I/357 : Gaia DR3 Part 3. Non-single stars (Gaia Collaboration, 2022)VII/233 : 2MASS All-Sky Extended Source Catalog (XSC) (IPAC/UMass, 2003-2006)J/ApJ/530/783 : The r-process enriched giant HD 115444 (Westin+, 2000)J/A+A/439/129 : HERES II. Spectroscopic analysis (Barklem+, 2005)J/ApJ/652/1585 : Bright metal-poor stars from HES survey (Frebel+, 2006)J/ApJ/645/613 : Abundances of HD 221170 (Ivans+, 2006)J/ApJ/724/341 : Nucleosynthesis of massive metal-free stars (Heger+, 2010)J/A+A/516/A46 : HE 2327-5642 abundance analysis (Mashonkina+, 2010)J/A+A/516/A46 : HE 2327-5642 abundance analysis (Mashonkina+, 2010)J/ApJ/724/975 : Heavy elements abund. of metal-poor stars (Roederer+, 2010)J/MNRAS/444/392 : Synthetic Stellar Photometry. I. (Casagrande+, 2014)J/A+A/569/A43 : HE 2252-4225 abundance analysis (Mashonkina+, 2014)J/A+A/569/A43 : HE 2252-4225 abundance analysis (Mashonkina+, 2014)J/ApJ/797/21 : Carbon-enhanced metal-poor stars (Placco+, 2014)J/AJ/147/136 : Stars of very low metal abundance. VI. (Roederer+, 2014)J/ApJ/812/109 : HST & Keck sp. of bright CEMP-s stars (Placco+, 2015)J/ApJ/824/L19 : CEMP star BD+44493 EWs (Roederer+, 2016)J/ApJ/838/44 : Abund. of the brightest member of Tuc III (Hansen+, 2017)J/A+A/607/A91 : CS 29497-004 abundances (Hill+, 2017)J/ApJ/844/18 : RAVE J203843.2-002333 high-res. spectroscopy (Placco+, 2017)J/ApJ/864/43 : Abund. of 3 bright extremely metal-poor giants (Cain+, 2018)J/ApJ/862/174 : Spectroscopy obs. of RAVE J094921.8-161722 (Gull+, 2018)J/ApJ/858/92 : RPA Southern Pilot Search of 107 Stars (Hansen+, 2018)J/AJ/155/256 : Sp. validation of RAVE metal-poor stars (Placco+, 2018)J/AJ/156/179 : r-process-enhanced field stars kinematics (Roederer+, 2018)J/ApJ/865/129 : Abundance analysis of HD 222925 (Roederer+, 2018)J/ApJ/868/110 : R-Process Alliance: 1st release in Gal. halo (Sakari+, 2018)J/MNRAS/489/5900 : Extremely metal-poor stars in SkyMapper DR1.1 (Da+, 2019)J/ApJ/870/122 : Spectroscopy of low-metallicity star cand. (Placco+, 2019)J/ApJ/874/148 : Metal-poor star RAVE J093730.5-062655 abund. (Sakari+, 2019)J/ApJ/898/40 : 2MASS J15213995-3538094 abundances from HRS (Cain+, 2020)J/ApJ/898/150 : High-res. MIKE obs. of metal-poor stars (Ezzeddine+, 2020)J/ApJS/249/30 : R-Process Alliance: metal-poor star sp. (Holmbeck+, 2020)J/ApJ/903/88 : Ions individual abund. in LAMOST J1109+0754 (Mardini+, 2020)J/ApJ/897/78 : RAVE J183013.5-455510 EW measurements (Placco+, 2020)J/ApJ/891/39 : LAMOST DR3 VMP stars of the Gal. halo (Yuan+, 2020)J/ApJ/908/79 : r-process Alliance; abundances in 519 stars (Gudin+, 2021)J/A+A/665/A57 : Substructure in the stellar halo. I. (Lovdal+, 2022)J/ApJS/262/8 : Sp. of low-metallicity S-PLUS stars (Placco+, 2022)J/ApJS/260/27 : R-Process Alliance: UV sp. of HD 222925 (Roederer+, 2022)J/ApJ/949/48 : High-res. sp. obs. of stars in TriAnd (Abuchaim+, 2023)J/ApJ/943/23 : R-Process Alliance (RPA). II. Halo RPE stars (Shank+, 2023)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/959/60https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/959/60http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/959/60https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/959/60https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/959/60http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/959/60GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/ApJ/959/60/table2Atomic data and derived abundancesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIonIon identifierphys.atmol.ionStagecharlambda[3694.19/8806.76] Wavelength; Angstroms0.1nmem.wlfloatExPot[0/4.4]? Excitation potentialeVphys.atmol.excitationfloatnullablelog(gf)[-3.34/0.81]? log oscillator strengthphys.atmol.oscStrengthfloatnullableEW[5.7/178]? Equivalent width; milli-Angstroms1e-13mspect.line.eqWidthfloatnullablef_EW[s] Indicates abundance is from spectral synthesismeta.codecharlogeps(x)[-1.75/4.87] log number abundancelog(Sun)phys.abundfloatRef[1/22] Reference code (1)meta.noteintNLTE[-0.37/1]? NLTE abundance correction (2)log(Sun)arith.factor;phys.abundfloatnullable