J/AJ/162/229ivo://CDS.VizieR/J/AJ/162/229doi:10.26093/cds/vizier.51620229CDSReggiani H.Schlaufman K.C.Casey A.R.Simon J.D.Ji A.P.2022-03-14T06:26:46Z2022-03-04T06:55:04ZCDS support team

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

cds-question@unistra.frmagellanic-cloudschemical-abundanceschemically-peculiar-starsvisible-astronomyspectroscopyThe chemical abundances of a galaxy's metal-poor stellar population can be used to investigate the earliest stages of its formation and chemical evolution. The Magellanic Clouds are the most massive of the Milky Way's satellite galaxies and are thought to have evolved in isolation until their recent accretion by the Milky Way. Unlike the Milky Way's less massive satellites, little is known about the Magellanic Clouds' metal-poor stars. We have used the mid-infrared metal-poor star selection of Schlaufman & Casey and archival data to target nine LMC and four SMC giants for high-resolution Magellan/MIKE spectroscopy. These nine LMC giants with -2.4<~[Fe/H]<~-1.5 and four SMC giants with -2.6<~[Fe/H]<~-2.0 are the most metal-poor stars in the Magellanic Clouds yet subject to a comprehensive abundance analysis. While we find that at constant metallicity these stars are similar to Milky Way stars in their {alpha}, light, and iron-peak elemental abundances, both the LMC and SMC are enhanced relative to the Milky Way in the r-process element europium. These abundance offsets are highly significant, equivalent to 3.9{sigma} for the LMC, 2.7{sigma} for the SMC, and 5.0{sigma} for the complete Magellanic Cloud sample. We propose that the r-process enhancement of the Magellanic Clouds' metal-poor stellar population is a result of the Magellanic Clouds' isolated chemical evolution and long history of accretion from the cosmic web combined with r-process nucleosynthesis on a timescale longer than the core-collapse supernova timescale but shorter than or comparable to the thermonuclear (i.e., Type Ia) supernova timescale.2021AJ....162..229Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/162/229CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)I/337 : Gaia DR1 (Gaia Collaboration, 2016)III/284 : APOGEE-2 data from DR16 (Johnsson+, 2020)V/154 : Sloan Digital Sky Surveys (SDSS), Release 16 (DR16) (Ahumada+, 2020)J/ApJ/743/156 : NEOWISE observations NEOs: preliminary results (Mainzer+, 2011)J/A+A/560/A44 : Abundances of LMC bar and disk stars (Van der Swaelmen+, 2013)J/AJ/145/107 : Zr, Ba, La, & Eu abundances 19 open clusters (Jacobson+, 2013)J/ApJ/767/134 : Abundances of red giant stars in UFD galaxies (Vargas+, 2013)J/AJ/147/136 : Stars very low metal abundance. VI. Abundances (Roederer+, 2014)J/ApJ/769/57 : Equivalent widths of metal-poor stars (Frebel+, 2013)J/ApJ/780/59 : Araucaria project: eclipsing binaries in SMC (Graczyk+, 2014)J/ApJ/789/147 : Star formation histories of LG dwarf galaxies (Weisz+, 2014)J/ApJ/797/13 : Abundances of bright metal-poor stars (Schlaufman+, 2014)J/MNRAS/442/1680 : Red giants in SMC. Abundances (Dobbie+, 2014)J/ApJ/807/171 : SkyMapper Survey metal-poor star spectroscopy (Jacobson+, 2015)J/A+A/586/A120 : Grid of 1D models for Mg line formation (Osorio+, 2016)J/AJ/151/82 : 4 brightest red giants in the UFD galaxy Ret 2 (Roederer+, 2016)J/AJ/151/144 : ASPCAP weights for 15 APOGEE chemical elements (Garcia+, 2016)J/ApJ/816/49 : Spitzer/IRAC observations of SMC Cepheids (Scowcroft+, 2016)J/ApJ/830/93 : Abundances of the Ret II brightest red giant members (Ji+, 2016)J/A+A/608/A46 : Constraining cosmic scatter (Reggiani+, 2017)J/AcA/67/297 : OGLE Galactic center Cepheids and RR Lyrae (Soszynski+, 2017)J/ApJ/838/44 : Abundances of the brightest member of Tuc III (Hansen+, 2017)J/ApJ/850/179 : 2MASSJ15111324-2130030 metal-poor star abund. (Casey+, 2017)J/A+A/616/A12 : Gaia DR2 sources in GC and dSph (Gaia Collaboration+, 2018)J/AcA/68/89 : VI light curves of MC type II Cepheids (Soszynski+, 2018)J/AJ/156/18 : APOGEE DR14:Binary companions evolved stars (Price-Whelan+, 2018)J/ApJ/858/92 : RPA Southern Pilot Search of 107 Stars (Hansen+, 2018)J/ApJ/863/89 : Gaia DR2 PMs of stars in ultra-faint MW satellites (Simon, 2018)J/ApJ/868/110 : R-Process Alliance 1st release in Galactic halo (Sakari+, 2018)J/A+A/627/A177 : Non-LTE analysis of K I in late-type stars (Reggiani+, 2019)J/ApJ/882/177 : Abundances of 4 member stars of Tucana III (Marshall+, 2019)J/AJ/160/173 : Abundances of metal-poor stars in Inner Bulge (Reggiani+, 2020)J/AJ/160/181 : Chemical abundances in red giants with Magellan (Ji+, 2020)J/ApJ/889/177 : RGB abundances in disk, stream & halo of M31 (Escala+, 2020)J/ApJ/895/78 : [Fe/H] and [{alpha}/Fe] in M31 dwarf galaxies (Wojno+, 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 spectro. (Holmbeck+, 2020)J/ApJS/252/23 : E(V-I) reddening map MCs from OGLE-IV RC stars (Skowron+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/162/229https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/162/229http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/162/229https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/162/229https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/162/229http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/162/229GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/162/229/table1 (Log of Magellan/MIKE observations)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/162/229/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/162/229/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/162/229/table1?GETtext/xml+votable180.050000true6.3269583-71.668750.0055555555555555566/33054 33096 33103 33137 33323 33825 37423https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/162/229?format=asciiOpticaldefaultJ/AJ/162/229/table1Log of Magellan/MIKE observationsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint2MASS2MASS identifiermeta.id;meta.maincharprimaryGalGalaxy identifier; Small/Large Magellanic Cloudmeta.notecharRAJ2000[0/6] Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of declinationpos.eq.dec;meta.mainObs[2016/2020] Year of observationstime.epochSlit[0.7/1] Slit widtharcsecstat.snrfloatTexp[3584/25200] Exposure timestime.duration;obs.exposureintRVel[100/357] Radial velocitykm/sphys.veloc;pos.heliocentricfloate_RVel[0.9/4] Error on RVelkm/sstat.error;spect.dopplerVelocfloatS/N4500[14/30] Signal to noise ratio at 4500{AA}stat.snrintS/N6500[31/76] Signal to noise ratio at 6500{AA}stat.snrintNobsNumber of observations for this star (table2)meta.numberintnullableSimbadSimbad column added by the CDSstat.snrcharJ/AJ/162/229/table2Atomic data, equivalent-width, & individual-line abundance inferencesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint2MASS2MASS designationmeta.id;meta.maincharGalGalaxy identifier; Small/Large Magellanic Cloudmeta.notecharWave[3999/7789] Wavelength; Angstroms0.1nmem.wldoubleSpeciesSpecies identifiermeta.idcharExPot[0/5.09] Excitation potentialeVphys.atmol.excitationfloatloggf[-5.63/0.55] log oscillator strengthphys.atmol.oscStrengthfloatEW[1.9/3149]? Equivalent width; milli-Angstroms1e-13mspect.line.eqWidthfloatnullableloge[-1.47/7.04] log Abundancephys.abundfloat