J/ApJ/850/179ivo://CDS.VizieR/J/ApJ/850/179doi:10.26093/cds/vizier.18500179CDSCasey A.R.Schlaufman K.C.2018-09-28T14:10:02Z2018-08-17T15:57:44ZCDS support team

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

cds-question@unistra.frchemical-abundancesline-intensitieschemically-peculiar-starsvisible-astronomyspectroscopyThe rapid neutron-capture or r-process is thought to produce the majority of the heavy elements (Z>30) in extremely metal-poor stars. The same process is also responsible for a significant fraction of the heavy elements in the Sun. This universality of the r-process is one of its characteristic features, as well as one of the most important clues to its astrophysical origin. We report the discovery of an extremely metal-poor field giant with [Sr,Ba/H]~-6.0 and [Sr,Ba/Fe]~-3.0, the lowest abundances of strontium and barium relative to iron ever observed. Despite its low abundances, the star 2MASS J151113.24-213003.0 has [Sr/Ba]=-0.11+/-0.14, therefore its neutron-capture abundances are consistent with the main solar r-process pattern that has [Sr/Ba]=-0.25. It has been suggested that extremely low neutron-capture abundances are a characteristic of dwarf galaxies, and we find that this star is on a highly eccentric orbit with an apocenter >~100kpc that lies in the disk of satellites in the halo of the Milky Way. We show that other extremely metal-poor stars with low [Sr,Ba/H] and [Sr,Ba/Fe] plus solar [Sr/Ba] tend to have orbits with large apocenters, consistent with a dwarf galaxy origin for this class of object. The nucleosynthesis event that produced the neutron-capture elements in 2MASS J151113.24-213003.0 must produce both strontium and barium together in the solar ratio. We exclude contributions from the s-process in intermediate-mass asymptotic giant branch or fast-rotating massive metal-poor stars, pair-instability supernovae, the weak r-process, and neutron-star mergers. We argue that the event was a Pop III or extreme Pop II core-collapse supernova explosion.2017ApJ...850..179Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/850/179CatalogResearchIsServedByTAP VizieR generic servicerelated-toII/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)I/317 : The PPMXL Catalog (Roeser+ 2010)I/320 : SPM 4.0 Catalog (Girard+, 2011)I/339 : Hot Stuff for One Year (HSOY) (Altmann+, 2017)J/A+A/416/1117 : Abundances in the early Galaxy (Cayrel+, 2004)J/ApJ/681/1524 : Detailed abundances for 28 metal-poor stars (Lai+, 2008)J/A+A/501/519 : Extremely metal-poor turnoff stars (Bonifacio+, 2009)J/ApJS/182/80 : Rare earth abundances (Sneden+, 2009)J/ApJ/724/341 : Nucleosynthesis of massive metal-free stars (Heger+, 2010)J/ApJ/711/573 : Abundances in a halo stellar stream (Roederer+, 2010)J/ApJ/749/77 : MW halo. III. Statistical abundances (Schlaufman+, 2012)J/ApJ/778/56 : Hamburg/ESO Survey extremely metal-poor stars (Cohen+, 2013)J/ApJ/769/57 : Equivalent widths of metal-poor stars (Frebel+, 2013)J/ApJ/771/67 : Abundances for 97 metal-poor stars. II. (Ishigaki+, 2013)J/ApJ/762/26 : Most metal-poor stars. II. Galactic halo stars (Yong+, 2013)J/A+A/562/A146 : Chemical abundances of 8 metal-poor stars (Ishigaki+, 2014)J/A+A/571/A47 : Linelist of CH in stellar atmospheres (Masseron+, 2014)J/AJ/147/136 : Stars of very low metal abundance. VI. (Roederer+, 2014)J/ApJ/797/13 : Abundances of bright metal-poor stars (Schlaufman+, 2014)J/ApJ/835/81 : Bright metal-poor stars from HES Survey. II. (Beers+, 2017)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/850/179https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/850/179http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/850/179https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/850/179https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/850/179http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/850/179GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/ApJ/850/179/table3Individual line abundances of 2MASS J151113.24-213003.0SpeciesSpecies identifierphys.atmol.ionStagecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambda[3566.3/7800.3] Wavelength in Angstroms0.1nmem.wlfloatExPot[0/9.2]? Lower excitation potentialeVphys.atmol.excitation;stat.minfloatnullableFlag[s] s: Abundance derived by spectral synthesismeta.code.errorcharlog(gf)[-5.7/0.7]? Log oscillator strengthphys.atmol.oscStrengthfloatnullableEW[4/203.7]? Equivalent width of Species (1)1e-13mspect.line.eqWidthfloatnullableE_EW[0.6/8.3]? Upper limit uncertainty in EW (1)1e-13mstat.error;stat.maxfloatnullablee_EW[0.8/6.1]? Lower limit uncertainty in EW (1)1e-13mstat.error;spect.line.eqWidthfloatnullablel_log(X)Limit flag on log(X)meta.code.errorcharlog(X)[-3.7/7] Log abundancelog(Sun)phys.abundfloat