J/ApJ/948/38ivo://CDS.VizieR/J/ApJ/948/38doi:10.26093/cds/vizier.19480038CDSJeong M.Lee Y.S.Beers T.C.Placco V.M.Kim Y.K.Koo J.-R.,Lee H.-G.Yang S.-C.2025-08-11T20:15:11Z2025-06-30T15:23:38ZCDS support team

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

cds-question@unistra.frchemical-abundancesvisible-astronomyspectroscopychemically-peculiar-starseffective-temperatureWe present stellar parameters and abundances of 13 elements for 18 very metal-poor (VMP; [Fe/H]{<}-2.0) stars, selected as extremely metal-poor (EMP; [Fe/H]{<}-3.0) candidates from the Sloan Digital Sky Survey (SDSS) and Large sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) survey. High-resolution spectroscopic observations were performed using GEMINI-N/GRACES. We find 10 EMP stars among our candidates, and we newly identify three carbon-enhanced metal-poor stars with [Ba/Fe]<0. Although chemical abundances of our VMP/EMP stars generally follow the overall trend of other Galactic halo stars, there are a few exceptions. One Na-rich star ([Na/Fe]=+1.14) with low [Mg/Fe] suggests a possible chemical connection with second-generation stars in a globular cluster. The progenitor of an extremely Na-poor star ([Na/Fe]=-1.02) with high K- and Ni-abundance ratios may have undergone a distinct nucleosynthesis episode, associated with core-collapse supernovae (SNe) having a high explosion energy. We have also found a Mg-rich star ([Mg/Fe]=+0.73) with slightly enhanced Na and extremely low [Ba/Fe], indicating that its origin is not associated with neutron-capture events. On the other hand, the origin of the lowest Mg abundance ([Mg/Fe]=-0.61) star could be explained by accretion from a dwarf galaxy, or formation in a gas cloud largely polluted by SNe Ia. We have also explored the progenitor masses of our EMP stars by comparing their chemical-abundance patterns with those predicted by Population III SNe models, and find a mass range of 10-26M_{sun}_, suggesting that such stars were primarily responsible for the chemical enrichment of the early Milky Way.2023ApJ...948...38Jhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/948/38CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)V/156 : LAMOST DR7 catalogs (Luo+, 2019)V/154 : Sloan Digital Sky Surveys (SDSS), Release 16 (DR16) (Ahumada+, 2020)I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)J/AJ/90/2089 : Stars of very low metal abundance. I (Beers+, 1985)J/AJ/103/1987 : Stars of very low metal abundance (Beers+ 1992)J/AJ/107/1577 : Halo red giants reddening (Anthony-Twarog+, 1994)J/AJ/119/2866 : Proper motions of metal-poor stars (Beers+, 2000)J/A+A/416/1117 : Abundances in the early Galaxy (Cayrel+, 2004)J/AJ/128/1177 : Galactic stellar abundances (Venn+, 2004)J/ApJ/652/1585 : Bright metal-poor stars from HES survey (Frebel+, 2006)J/ApJ/655/492 : Equivalent widths of 26 metal-poor stars (Aoki+, 2007)J/ApJ/658/367 : Abundances of carbon stars in Galactic halo (Komiya+, 2007)J/AJ/136/2070 : SEGUE stellar parameter pipeline. III. (Allende Prieto+, 2008)J/A+A/484/721 : HES survey. IV. Candidate metal-poor stars (Christlieb+, 2008)J/AJ/136/2050 : SEGUE stellar parameter pipeline. II. (Lee+, 2008)J/A+A/497/497 : Physical parameters from JHK flux (Gonzalez-Hernandez+, 2009)J/A+A/503/545 : Equivalent widths of Li, Na, Fe, Ca in NGC 6397 (Lind+, 2009)J/AJ/137/4377 : List of SEGUE plate pairs (Yanny+, 2009)J/A+A/512/A54 : Teff and Fbol from Infrared Flux Method (Casagrande+, 2010)J/ApJ/724/341 : Nucleosynthesis of massive metal-free stars (Heger+, 2010)J/A+A/509/A93 : Carbon-enhanced metal-poor stars (Masseron+, 2010)J/A+A/522/A26 : Fe Abundances in metal-poor stars (Sbordone+ 2010)J/AJ/141/90 : SEGUE stellar parameter pipeline. V. (Lee+, 2011)J/A+A/534/A136 : Halo red giants from the SEGUE survey (Martell+, 2011)J/AJ/141/89 : SEGUE stellar parameter pipeline. IV. (Smolinski+, 2011)J/AJ/141/175 : Abundances in M15 RGB/RHB stars (Sobeck+, 2011)J/ApJ/760/86 : Equivalent widths for 13 NGC2419 RGB stars (Cohen+, 2012)J/AJ/145/13 : Metal-poor stars from SDSS/SEGUE. I. Abundances (Aoki+, 2013)J/ApJ/769/57 : Equivalent widths of metal-poor stars (Frebel+, 2013)J/ApJ/773/33 : Analysis of the metal-poor subgiant BD+44 493 (Ito+, 2013)J/ApJ/762/26 : Most metal-poor stars. II. Galactic halo stars (Yong+, 2013)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/A+A/571/A40 : Abundances in 2 extremely metal-poor stars (Spite+, 2014)J/ApJ/807/171 : SkyMapper Survey metal-poor star spec. (Jacobson+, 2015)J/AJ/150/187 : Abundances and stellar parameters of LAMOST stars (Lee+, 2015)J/ApJ/812/109 : HST & Keck spectroscopy of bright CEMP-s stars (Placco+, 2015)J/A+A/586/A158 : Binary properties of CH and CEMP stars (Jorissen+, 2016)J/ApJS/222/19 : KPNO spectroscopy of G & K dwarfs HIP stars (Kim+, 2016)J/ApJ/833/20 : Carbon-enhanced metal-poor (CEMP) star abund. (Yoon+, 2016)J/AJ/154/52 : Metal-poor stars from SDSS/SEGUE. I. (Matsuno+, 2017)J/A+A/601/A112 : GES iDR4 Mg-Al anticorrelation in GCs (Pancino+, 2017)J/A+A/608/A46 : Constraining cosmic scatter (Reggiani+, 2017)J/A+A/618/A133 : Non standard s-process in massive rot. stars (Choplin+, 2018)J/ApJ/857/46 : Modelled vs observed abundances of EMP stars (Ishigaki+, 2018)J/ApJ/897/78 : RAVE J183013.5-455510 equivalent-widths (Placco+, 2020)J/ApJ/905/20 : Metal-poor stars observed with SALT/HRS (Rasmussen+, 2020)J/A+A/654/A170 : Abundances of metal-poor stars (Matas Pinto+, 2021)J/MNRAS/507/43 : Study of the Spite plateau with GALAH DR3 (Simpson+, 2021)J/ApJ/931/147 : Very metal-poor stars with LAMOST & Subaru. II. (Li+, 2022)J/ApJS/262/8 : Sp. follow-up of low-metallicity S-PLUS stars (Placco+, 2022)J/ApJS/259/60 : SEGUE-2 updated stellar parameter pipeline (Rockosi+, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/948/38https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/948/38http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/948/38https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/948/38https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/948/38http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/948/38GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/948/38/table1 (Observation details of our program stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/948/38/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/948/38/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/948/38/table1?GETtext/xml+votable180.050000true119.6017543.61205560.0055555555555555566/337 1210 2426 2437 4974 5150 5809 6412 6558 7020 9072 10009 11927 13386 13411 18354 19486 20358 26202 31571https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/948/38?format=asciiOpticaldefaultJ/ApJ/948/38/table1Observation details of our program starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintProgIDGemini program identifiermeta.id;obscharNameStar namemeta.id;meta.maincharIDAbbreviated identifiermeta.idcharprimaryf_ID[c] c = reference star (1)meta.codecharDateDate of observation (UT)'Y:M:D'time.epochnullableRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of declination (J2000)pos.eq.dec;meta.maingmag[9.1/16.5] g-band magnitudemagphot.mag;em.opt.Bfloatn_gmag[a] a = V magnitudemeta.note;phot.mag;em.optcharExpExposure timestime.duration;obs.exposurecharf_Exp[b] Flag on exposure time (1)meta.codecharS/N[31/93] Signal-to-noise ratio; average value around 5500{AA}pixel**-1stat.snrintHRV[-379/145] Heliocentric radial velocitykm/sspect.dopplerVeloc;pos.heliocentricfloatAbDisplay the abundance measurements for this star (link to Table 8)meta.ref.urlcharSimbadNameSimbad column added by the CDSmeta.idcharnullableJ/ApJ/948/38/table6Line listsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSpecies[11.0/56.1] Species code identifier (1)meta.id;phys.atmol.ionStagefloatlambda[4702.99/7698.96] Wavelength; Angstroms0.1nmem.wlfloatExPot[0/4.55] Excitation potentialeVphys.atmol.excitationfloatlog(gf)[-5.46/0.65] log oscillator strengthphys.atmol.oscStrengthfloatJ/ApJ/948/38/table8*Detailed chemical abundances for each objectIDShort object identifier; see Table 1meta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSpeciesSpecies identifiermeta.id;phys.atmol.ionStagecharN[1/121]? Number of linesmeta.numberintnullablel_loge(X)Upper limit flag on loge(X)meta.code.errorcharloge(X)[-2.9/5.9]? Log abundance of Speciesphys.abundfloatnullablel_[X/Fe]Upper limit flag on [X/Fe]meta.code.error;phys.abundchar[X/Fe][-2.1/4.3]? Log Species number abundance relative to Felog(Sun)phys.abundfloatnullableSE[0.02/0.8]? Standard error in the mean of [X/Fe]log(Sun)stat.error;phys.abundfloatnullableDelTeff[0/0.2]? Uncertainty in [X/Fe] due to +/-100 in T_eff_log(Sun)stat.error;phys.abundfloatnullableDellogg[0/0.1]? Uncertainty in [X/Fe] due to +/-0.2dex in log (g)log(Sun)stat.error;phys.abundfloatnullableDelVt[0/0.1]? Uncertainty in [X/Fe] due to +/-0.2km/s in V_turb_log(Sun)stat.error;phys.abundfloatnullableTE[0.02/0.4]? Total error in [X/Fe] (1)log(Sun)stat.error;phys.abundfloatnullable