J/ApJ/898/40ivo://CDS.VizieR/J/ApJ/898/40doi:10.26093/cds/vizier.18980040CDSCain M.Frebel A.Ji A.P.Placco V.M.Ezzeddine R.Roederer I.U.,Hattori K.Beers T.C.Melendez J.Hansen T.T.Sakari C.M.2022-09-30T20:58:23Z2021-12-08T11:00:57ZCDS support team

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

cds-question@unistra.frchemical-abundancesline-intensitieschemically-peculiar-starsvisible-astronomyspectroscopyWe report the discovery of J1521-3538, a bright (V=12.2), very metal-poor ([Fe/H]=-2.8) strongly r-process-enhanced field horizontal branch star, based on a high-resolution, high signal-to-noise Magellan/MIKE spectrum. J1521-3538 shows the largest r-process element overabundance in any known r-process-enhanced star, with [Eu/Fe]=+2.2, and its chemical abundances of 22 neutron-capture elements closely match the scaled solar r-process pattern. J1521-3538 is also one of few known carbon-enhanced metal-poor stars with r-process enhancement (CEMP-r stars), as found after correcting the measured C abundance for the star's evolutionary status. We propose to extend the existing classification of moderately enhanced (+0.3<=[Eu/Fe]<=+1.0) r-I and strongly r-process enhanced ([Eu/Fe]>+1.0) r-II stars to include an r-III class, for r-process stars such as J1521-3538, with [Eu/Fe]>+2.0 and [Ba/Eu]{<}-0.5, or >=100 times the solar ratio of europium to iron. Using cosmochronometry, we estimate J1521-3538 to be 12.5+/-5Gyr and 8.9+/-5Gyr, using two different sets of initial production ratios. These ages are based on measurements of the Th line at 4019{AA} and other r-process element abundances. This is broadly consistent with the old age of a low-mass, metal-poor field red horizontal branch star. J1521-3538 likely originated in a low-mass dwarf galaxy that was later accreted by the Milky Way, as evidenced by its highly eccentric orbit.2020ApJ...898...40Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/898/40CatalogResearchIsServedByTAP VizieR generic servicerelated-toIII/279 : RAVE 5th data release (Kunder+, 2017)I/350 : Gaia EDR3 (Gaia Collaboration, 2020)J/A+A/416/1117 : Abundances in the early Galaxy (Cayrel+, 2004)J/A+A/439/129 : HERES II. Spectroscopic analysis (Barklem+, 2005)J/AJ/132/137 : Abundances of extremely metal-poor carbon stars (Cohen+, 2006)J/ApJ/645/613 : Abundances of HD 221170 (Ivans+, 2006)J/AJ/132/85 : Equivalent width of 33 metal-poor RHB (Preston+, 2006)J/ApJ/655/492 : Equivalent widths of 26 metal-poor stars (Aoki+, 2007)J/ApJ/681/1524 : Detailed abundances for 28 metal-poor stars (Lai+, 2008)J/ApJ/679/1549 : Spec. of metal-poor star CS 17435-00532 (Roederer+, 2008)J/ApJS/182/80 : Rare earth abundances (Sneden+, 2009)J/ApJ/711/573 : Detailed abundances in a halo stellar stream (Roederer+, 2010)J/AJ/141/175 : Abundances in M15 RGB/RHB stars (Sobeck+, 2011)J/A+A/548/A42 : Average spectrum of HD140283 (Siqueira Mello+ 2012)J/ApJ/769/57 : Equivalent widths of metal-poor stars (Frebel+, 2013)J/ApJ/779/102 : Metallicities of RGB stars in dwarf galaxies (Kirby+, 2013)J/ApJ/762/26 : Most metal-poor stars. II. Galactic halo stars (Yong+, 2013)J/ApJ/794/58 : Metal-poor stars in the Galaxy thick disk (Beers+, 2014)J/ApJS/215/23 : FeI radiative lifetimes (Den Hartog+, 2014)J/A+A/569/A43 : HE 2252-4225 abundance analysis (Mashonkina+, 2014)J/A+A/571/A47 : Extensive linelist of CH in stellar atm. (Masseron+, 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/MNRAS/441/3127 : FeI oscillator strengths for Gaia-ESO (Ruffoni+, 2014)J/ApJS/214/26 : Line lists for CN isotopes transitions (Sneden+, 2014)J/A+A/571/A40 : Abundances in 2 extremely metal-poor stars (Spite+, 2014)J/ApJ/814/121 : CASH project. III. The CEMP star HE0414-0343 (Hollek+, 2015)J/ApJ/807/171 : SkyMapper Survey metal-poor star spec. (Jacobson+, 2015)J/ApJ/798/110 : Equivalent widths of LAMOST metal-poor stars (Li+, 2015)J/ApJ/812/109 : HST & Keck spectroscopy of bright CEMP-s stars (Placco+, 2015)J/A+A/574/A129 : The First CEMP star in the Sculptor dSph (Skuladottir+, 2015)J/ApJ/830/93 : Abundances of Ret II brightest red giant members (Ji+, 2016)J/ApJ/817/53 : Fe-group elemental abundances in HD84937 (Sneden+, 2016)J/ApJ/819/53 : Magellan/M2FS spec. of Tucana 2 & Grus 1 (Walker+, 2016)J/ApJ/835/81 : Bright metal-poor stars from HES Survey. II. (Beers+, 2017)J/ApJ/850/179 : 2MASS J15111324-2130030 metal-poor star abund. (Casey+, 2017)J/ApJ/847/142 : Ultra-metal-poor stars LTE & NLTE abund. (Ezzeddine+, 2017)J/A+A/607/A91 : CS 29497-004 abundances (Hill+, 2017)J/ApJ/844/18 : RAVE J203843.2-002333 high-resolution spec. (Placco+, 2017)J/A+A/612/A90 : Inelastic Fe+H collision data (Barklem, 2018)J/ApJ/864/43 : Abund. of 3 bright extremely metal-poor giants (Cain+, 2018)J/A+A/618/A141 : H-atom collisions NLTE corrections (Ezzeddine+, 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 : Spec. validation of RAVE metal-poor stars (Placco+, 2018)J/AJ/156/179 : Highly r-process-enhanced stars kinematics (Roederer+, 2018)J/ApJ/865/129 : Abundance analysis of HD 222925 (Roederer+, 2018)J/ApJ/874/148 : Metal-poor star RAVE J093730.5-062655 abund. (Sakari+, 2019)J/ApJ/891/39 : LAMOST DR3 very metal-poor stars of Gal. halo (Yuan+, 2020)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/898/40https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/898/40http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/898/40https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/898/40https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/898/40http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/898/40GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/ApJ/898/40/table2Line list and derived abundances for 2MASS J15213995-3538094recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIonElement identifierphys.atmol.ionStagecharlambda[3398.94/8688.62] Wavelength; Angstroms0.1nmem.wlfloatExPot[-0.6/4.47]? Excitation potentialeVphys.atmol.excitationfloatnullablelog(gf)[-3.9/2.94]? log oscillator strengthphys.atmol.oscStrengthfloatnullableEW[2.4/133]? Equivalent width; milli-Angstroms1e-13mspect.line.eqWidthfloatnullablef_EW[s] Indicates a synthesis linemeta.codecharl_logAbdLimit flag on logAbdmeta.code.errorcharlogAbd[-0.83/6.2] log derived abundancephys.abundfloat