J/ApJ/959/60 The EMP star SPLUS J142445.34-254247.1 with GHOST (Placco+, 2023)
SPLUS J142445.34-254247.1: an r-process-enhanced, actinide-boost, extremely
metal-poor star observed with GHOST.
Placco 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.
<Astrophys. J., 959, 60 (2023)>
=2023ApJ...959...60P 2023ApJ...959...60P
ADC_Keywords: Spectra, optical; Equivalent widths; Stars, metal-deficient;
Abundances; Stars, halo
Keywords: High resolution spectroscopy ; Stellar atmospheres ;
Narrow band photometry ; Chemical abundances ; Metallicity
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 logε(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☉, and the heavy-element (Z≥38) abundance
pattern can be reproduced by the yields from a neutron star merger
(1.66M☉ and 1.27M☉) 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.
Description:
SPLUS J142445.34-254247.1 was observed as part of the Southern
Photometric Local Universe Survey (S-PLUS) second data release (DR2;
Almeida-Fernandes+ 2022MNRAS.511.4590A 2022MNRAS.511.4590A). S-PLUS has a unique 12 broad-
and narrowband filter set, consisting of four Sloan Digital Sky Survey
(SDSS; g, r, i, z), one modified SDSS u, and seven narrowband filters.
Medium-resolution (R∼1500) spectroscopy for SPLUS J1424-2542 was
gathered on 2021 June 18, with the 8.1m Gemini-South telescope and the
GMOS instrument, as part of the Poor Weather program GS-2021A-Q-419.
Further details on the observing setup and data reduction are given in
Placco+ (2022, J/ApJS/262/8).
SPLUS J1424-2542 was followed up in high resolution using the newly
commissioned Gemini High-resolution Optical SpecTrograph (GHOST) at
Gemini-South. Observations were conducted on 2023 May 10, as part of
the GHOST System Verification (SV; Program ID: GS-2023A-SV-101) and
the data are publicly available at the Gemini Observatory Archive.
The wavelength coverage is 3474-5438Å for the blue camera and
5209-10608Å for the red camera with a standard resolution (R∼50000).
Objects:
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RA (ICRS) DE Designation(s)
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14 24 45.33 -25 42 47.1 SPLUS J1424-2542 = 2MASS J14244532-2542471
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 47 308 Atomic data and derived abundances
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See also:
II/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)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Ion Ion identifier
6- 12 F7.2 0.1nm lambda [3694.19/8806.76] Wavelength; Angstroms
14- 17 F4.2 eV ExPot [0/4.4]? Excitation potential
19- 23 F5.2 [-] log(gf) [-3.34/0.81]? log oscillator strength
25- 30 F6.2 10-13m EW [5.7/178]? Equivalent width; milli-Angstroms
32- 32 A1 --- f_EW [s] Indicates abundance is from
spectral synthesis
34- 38 F5.2 [Sun] logeps(x) [-1.75/4.87] log number abundance
40- 41 I2 --- Ref [1/22] Reference code (1)
43- 47 F5.2 [Sun] NLTE [-0.37/1]? NLTE abundance correction (2)
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Note (1): Reference code as follows:
1 = Placco et al. 2021RNAAS...5...92P 2021RNAAS...5...92P and 2021ascl.soft04027P
2 = Kramida et al. (2013)
3 = Biemont et al. 2011MNRAS.414.3350B 2011MNRAS.414.3350B
4 = Ljung et al. 2006A&A...456.1181L 2006A&A...456.1181L
5 = Kramida et al. (2013), using HFS/IS from
McWilliam 1998AJ....115.1640M 1998AJ....115.1640M when available;
6 = Lawler et al. 2001ApJ...556..452L 2001ApJ...556..452L, using HFS from
Ivans+ 2006, J/ApJ/645/613 when available;
7 = Lawler et al. 2009, J/ApJS/182/51
8 = Li et al. 2007PhyS...76..577L 2007PhyS...76..577L, using HFS from
Sneden+ 2009, J/ApJS/182/80
9 = Den Hartog et al. 2003ApJS..148..543D 2003ApJS..148..543D, using HFS/IS from
Roederer et al. 2008ApJ...675..723R 2008ApJ...675..723R when available;
10 = Lawler et al. 2006, J/ApJS/162/227, using HFS/IS from
Roederer et al. 2008ApJ...675..723R 2008ApJ...675..723R when available;
11 = Lawler et al. 2001ApJ...556..452L 2001ApJ...556..452L, using HFS/IS from
Ivans+ 2006, J/ApJ/645/613
12 = Den Hartog et al. 2006, J/ApJS/167/292
13 = Lawler et al. 2001ApJS..137..351L 2001ApJS..137..351L, using HFS from
Lawler et al. 2001ApJS..137..351L 2001ApJS..137..351L
14 = Wickliffe et al. 2000JQSRT..66..363W 2000JQSRT..66..363W
15 = Lawler et al. 2004ApJ...604..850L 2004ApJ...604..850L, using HFS from
Sneden+ 2009, J/ApJS/182/80
16 = Lawler et al. 2008ApJS..178...71L 2008ApJS..178...71L
17 = Wickliffe & Lawler 1997JOSAB..14..737W 1997JOSAB..14..737W, using HFS from
Sneden+ 2009, J/ApJS/182/80
18 = Sneden+ 2009, J/ApJS/182/80 for log(gf) value and HFS/IS;
19 = Lawler et al. 2007, J/ApJS/169/120
20 = Quinet et al. 2006A&A...448.1207Q 2006A&A...448.1207Q
21 = Xu et al. 2007JQSRT.104...52X 2007JQSRT.104...52X, using HFS/IS from
Cowan et al. 2005ApJ...627..238C 2005ApJ...627..238C
22 = Nilsson et al. 2002A&A...382..368N 2002A&A...382..368N
Note (2): Corrections from:
Na I = Lind et al. 2011A&A...528A.103L 2011A&A...528A.103L
Mg I = Bergemann et al. 2015ApJ...804..113B 2015ApJ...804..113B
Al I = Nordlander & Lind 2017A&A...607A..75N 2017A&A...607A..75N
Si I = Bergemann et al. 2013ApJ...764..115B 2013ApJ...764..115B
Ca I = Mashonkina et al. 2007A&A...461..261M 2007A&A...461..261M
Ti I = Bergemann 2011MNRAS.413.2184B 2011MNRAS.413.2184B
Ti II = Bergemann 2011MNRAS.413.2184B 2011MNRAS.413.2184B
Cr I = Bergemann & Cescutti 2010A&A...522A...9B 2010A&A...522A...9B
Mn I = Bergemann et al. 2019, J/A+A/631/A80
Fe I = Bergemann et al. 2012MNRAS.427...27B 2012MNRAS.427...27B
Co I = Bergemann et al. 2010MNRAS.401.1334B 2010MNRAS.401.1334B
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 28-Jan-2026