J/ApJ/830/93ivo://CDS.VizieR/J/ApJ/830/93doi:10.26093/cds/vizier.18300093CDSJi A.P.Frebel A.Simon J.D.Chiti A.2017-12-22T05:32:14Z2017-02-20T08:39:53ZCDS support team

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

cds-question@unistra.frgalaxiesspectroscopygiant-starschemical-abundancesradial-velocityline-intensitiesWe present chemical abundances derived from high-resolution Magellan/Magellan Inamori Kyocera Echelle spectra of the nine brightest known red giant members of the ultra-faint dwarf galaxy Reticulum II (Ret II). These stars span the full metallicity range of Ret II (-3.5<[Fe/H]< -2). Seven of the nine stars have extremely high levels of r-process material ([Eu/Fe]~1.7), in contrast to the extremely low neutron-capture element abundances found in every other ultra-faint dwarf galaxy studied to date. The other two stars are the most metal-poor stars in the system ([Fe/H]< -3), and they have neutron-capture element abundance limits similar to those in other ultra-faint dwarf galaxies. We confirm that the relative abundances of Sr, Y, and Zr in these stars are similar to those found in r-process halo stars, but they are ~0.5dex lower than the solar r-process pattern. If the universal r-process pattern extends to those elements, the stars in Ret II display the least contaminated known r-process pattern. The abundances of lighter elements up to the iron peak are otherwise similar to abundances of stars in the halo and in other ultra-faint dwarf galaxies. However, the scatter in abundance ratios is large enough to suggest that inhomogeneous metal mixing is required to explain the chemical evolution of this galaxy. The presence of low amounts of neutron-capture elements in other ultra-faint dwarf galaxies may imply the existence of additional r-process sites besides the source of r-process elements in Ret II. Galaxies like Ret II may be the original birth sites of r-process enhanced stars now found in the halo.2016ApJ...830...93Jhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/830/93CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJ/808/108 : M2FS stellar spectroscopy of Reticulum 2 (Walker+, 2015)J/ApJ/808/95 : Spectroscopy of Reticulum II (Simon+, 2015)J/ApJ/807/171 : SkyMapper Survey metal-poor star spectrosc. (Jacobson+, 2015)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/779/102 : Metallicities of RGB stars in dwarf galaxies (Kirby+, 2013)J/ApJ/767/134 : Abundances of red giant stars in UFD galaxies (Vargas+, 2013)J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012)J/ApJS/182/80 : Rare earth abundances (Sneden+, 2009)J/ApJS/162/227 : Transition probabilities for SmII (Lawler+, 2006)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/830/93https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/830/93http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/830/93https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/830/93https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/830/93http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/830/93GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/830/93/table1 (*Observed stars and stellar parameters)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/830/93/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/830/93/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/830/93/table1?GETtext/xml+votable180.050000true53.84938-54.068750.0055555555555555566/33626 33627https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/830/93?format=asciiOpticaldefaultJ/ApJ/830/93/table1*Observed stars and stellar parametersSimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDESStar identifier (JHHMMSS+DDMMSS)meta.id;meta.maincharExp[58/220] Exposure timemintime.duration;obs.exposureintVmag[16/18.7] V-band magnitude (1)magphot.mag;em.opt.VfloatS/N4[7/22] Signal to noise ratio per pixel at 4250{AA}stat.snrintS/N6[13/47] Signal to noise ratio per pixel at 6000{AA}stat.snrintHRV[60.9/71.6] Heliocentric velocitykm/sspect.dopplerVeloc;pos.heliocentricfloate_HRV[0.1/0.3] HRV uncertainty (2)km/sstat.errorfloatTeff[4608/5395] Effective temperatureKphys.temperature.effectiveinte_Teff[157/258] Teff uncertainty (3)Kstat.error;phys.temperature.effectiveintlogg[1/3.1] Log of surface gravitylog(cm.s**-2)phys.gravityfloate_logg[0.3/0.4] logg uncertainty (3)log(cm.s**-2)stat.errorfloatVt[1.3/2.4] Microturbulence velocitykm/sphys.veloc.microTurbfloate_Vt[0.2/0.5] Vt uncertainty (3)km/sstat.errorfloat[Fe/H][-3.6/-2] Metallicitylog(Sun)phys.abund.ZfloatIDLetter used as identifier in table 2; column added by CDSmeta.idcharEWsDisplay the equivalent width measurements for this starmeta.ref.urlchar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainJ/ApJ/830/93/table2Equivalent widthsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIonMolecule or Ion identifierphys.atmol.ionStagecharlambda[3743.3/6678] Wavelength in Angstroms0.1nmem.wlfloatExPot[0/4.4]? Excitation potentialeVphys.atmol.excitationfloatnullablelog(gf)[-5.7/0.7]? Log oscillator strengthphys.atmol.oscStrengthfloatnullableEW-A[17/179]? DES J033523-540407 equivalent width in milli-Angstroms1e-13mspect.line.widthfloatnullablef_EW-As=abundance determined with spectrum synthesismeta.codecharloge-A[-1.1/6.1]? DES J033523-540407 log abundancephys.abundfloatnullableEW-B[14/188]? DES J033607-540235 equivalent width in milli-Angstroms1e-13mspect.line.widthfloatnullablef_EW-Bs=abundance determined with spectrum synthesismeta.codecharloge-B[-0.9/5.9]? DES J033607-540235 log abundancephys.abundfloatnullableEW-C[19/236]? DES J033447-540525 equivalent width in milli-Angstroms1e-13mspect.line.widthfloatnullablef_EW-Cs=abundance determined with spectrum synthesismeta.codecharloge-C[-0.8/5.8]? DES J033447-540525 log abundancephys.abundfloatnullableEW-D[17/200]? DES J033531-540148 equivalent width in milli-Angstroms1e-13mspect.line.widthfloatnullablef_EW-Ds=abundance determined with spectrum synthesismeta.codecharl_loge-DLimit flag on loge-Dmeta.code.errorcharloge-D[-2/5.4]? DES J033531-540148 log abundancephys.abundfloatnullablel_EW-ELimit flag on EW-Emeta.code.error;spect.line.eqWidthcharEW-E[20/218]? DES J033548-540349 equivalent width in milli-Angstroms1e-13mspect.line.widthfloatnullablef_EW-Es=abundance determined with spectrum synthesismeta.codecharl_loge-ELimit flag on loge-Emeta.code.errorcharloge-E[-0.9/6.8]? DES J033548-540349 log abundancephys.abundfloatnullablel_EW-FLimit flag on EW-Fmeta.code.error;spect.line.eqWidthcharEW-F[36/193]? DES J033537-540401 equivalent width in milli-Angstroms1e-13mspect.line.widthfloatnullablef_EW-Fs=abundance determined with spectrum synthesismeta.codecharl_loge-FLimit flag on loge-Fmeta.code.errorcharloge-F[-0.6/6]? DES J033537-540401 log abundancephys.abundfloatnullablel_EW-GLimit flag on EW-Gmeta.code.error;spect.line.eqWidthcharEW-G[16/187]? DES J033556-540316 equivalent width in milli-Angstroms1e-13mspect.line.widthfloatnullablef_EW-Gs=abundance determined with spectrum synthesismeta.codecharl_loge-GLimit flag on loge-Gmeta.code.errorcharloge-G[-1.3/6.1]? DES J033556-540316 log abundancephys.abundfloatnullablel_EW-HLimit flag on EW-Hmeta.code.error;spect.line.eqWidthcharEW-H[32/194]? DES J033457-540531 equivalent width in milli-Angstroms1e-13mspect.line.widthfloatnullablef_EW-Hs=abundance determined with spectrum synthesismeta.codecharl_loge-HLimit flag on loge-Hmeta.code.errorcharloge-H[-0.06/6.7]? DES J033457-540531 log abundancephys.abundfloatnullablel_EW-ILimit flag on EW-Imeta.code.error;spect.line.eqWidthcharEW-I[40/203]? DES J033454-540558 equivalent width in milli-Angstroms1e-13mspect.line.widthfloatnullablef_EW-Is=abundance determined with spectrum synthesismeta.codecharl_loge-ILimit flag on loge-Imeta.code.errorcharloge-I[-0.2/7.3]? DES J033454-540558 log abundancephys.abundfloatnullable