J/ApJ/817/41ivo://CDS.VizieR/J/ApJ/817/41doi:10.26093/cds/vizier.18170041CDSJi A.P.Frebel A.Simon J.D.Geha M.2017-12-22T05:32:47Z2016-04-26T15:42:57ZCDS support team

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

cds-question@unistra.frchemical-abundancesline-intensitiesgiant-starsgalaxiesvisible-astronomyWe present high-resolution Magellan/MIKE spectra of the four brightest confirmed red giant stars in the ultra-faint dwarf galaxy Bootes II (Boo II). These stars all inhabit the metal-poor tail of the BooII metallicity distribution function. The chemical abundance pattern of all detectable elements in these stars is consistent with that of the Galactic halo. However, all four stars have undetectable amounts of neutron-capture elements Sr and Ba, with upper limits comparable to the lowest ever detected in the halo or in other dwarf galaxies. One star exhibits significant radial velocity variations over time, suggesting it to be in a binary system. Its variable velocity has likely increased past determinations of the Boo II velocity dispersion. Our four stars span a limited metallicity range, but their enhanced {alpha}-abundances and low neutron-capture abundances are consistent with the interpretation that Boo II has been enriched by very few generations of stars. The chemical abundance pattern in Boo II confirms the emerging trend that the faintest dwarf galaxies have neutron-capture abundances distinct from the halo, suggesting the dominant source of neutron-capture elements in halo stars may be different than in ultra-faint dwarfs.2016ApJ...817...41Jhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/817/41CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toV/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)J/ApJS/216/10 : DUSTiNGS. I. The Good Source Catalog (Boyer+, 2015)J/MNRAS/440/2665 : SDSS J021933.13+200830.2 spectroscopy (Roederer+, 2014)J/A+A/562/A146 : Chemical abundances of 8 metal-poor stars (Ishigaki+, 2014)J/ApJ/779/102 : Metallicities of RGB stars in dwarf galaxies (Kirby+, 2013)J/ApJ/769/57 : Equivalent widths of metal-poor stars (Frebel+, 2013)J/ApJ/767/134 : Abundances of red giant stars in UFD galaxies (Vargas+, 2013)J/ApJ/763/61 : Abundances of 7 red giant members of BootesI (Gilmore+, 2013)J/ApJ/762/26 : Most metal-poor stars. II. Galactic halo stars (Yong+, 2013)J/AJ/144/4 : Dwarf galaxy data in the Local Group (McConnachie+, 2012)J/ApJ/711/350 : Metal-poor giant Boo-1137 abundances (Norris+, 2010)J/ApJ/655/492 : Equivalent widths of 26 metal-poor stars (Aoki+, 2007)http://www.sdss.org/ : SDSS home pagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/817/41https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/817/41http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/817/41https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/817/41https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/817/41http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/817/41GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/817/41/stars (Observing details and stellar parameters of the red giant stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/817/41/stars?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/817/41/stars?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/817/41/stars?GETtext/xml+votable180.050000true209.46333312.8602780.0055555555555555566/26487https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/817/41?format=asciiOpticaldefaultJ/ApJ/817/41/starsObserving details and stellar parameters of the red giant starsSimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameSDSS truncated name (JHHMMSS.s+DDMMSS.s)meta.id;meta.maincharRAJ2000[13] Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000[12] Degree of declination (J2000)pos.eq.dec;meta.mainDateObservation date(s)time.epoch;obscharSlit[0.7/1] Slit width (1)arcsecspect.line.widthfloatExp[5.8/12.2] Exposure timehtime.duration;obs.exposurefloatgmag[19.2/19.6] g-band magnitudemagphot.mag;em.opt.BfloatVmag[18.8/19.2] V-band magnitude (2)magphot.mag;em.opt.VfloatS/N[11/17] Signal to noise ratio at 5300{AA} (3)stat.snrintS/N6[21/29] Signal to noise ratio at 6000{AA} (3)stat.snrintTeff[4936/5192] Effective temperatureKphys.temperature.effectiveintlogg[1.8/2.6] Lof of surface gravitylog(cm.s**-2)phys.gravityfloatxi[1.6/2.1] Microturbulent velocitykm/sphys.velocfloat[Fe/H][-3/-2.6] Metallicity [Fe/H]log(Sun)phys.abund.ZfloatTphot[5005/5217] Photometric temperature (4)Kphys.temperatureintB15Display data from Boyer+, 2015 within 0.6"meta.ref.urlintnullableNabNumber of chemical abundances for this starmeta.numberintnullableEWsDisplay the equivalent width measurements for this starmeta.ref.urlcharSloanDisplay the online SDSS data for the nearest objectmeta.ref.urlcharJ/ApJ/817/41/table2Equivalent Widthsl_EW4Limit flag on EW4meta.code.errorcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIonElement/Ion/Molecule designationphys.atmol.ionStagecharlambda[3783.5/6678]? Wavelength; Angstroms0.1nmem.wlfloatnullableExPot[0/4.4]? Excitation potentialeVphys.atmol.excitationfloatnullablelog(gf)[-5.7/0.7]? Log oscillator strengthphys.atmol.oscStrengthfloatnullablel_EW1Limit flag on EW1meta.code.errorcharEW1[15/197.2]? SDSS J135751.2+125137.0 equivalent width (in milli-Angstroms)1e-13mspect.line.eqWidthfloatnullablef_EW1[s] Flag on EW1 (1)meta.codecharl_loge1Limit flag on loge1meta.code.errorcharloge1[-2.2/6]? SDSS J135751.2+125137.0 log abundancephys.abundfloatnullableEW2[26/253]? SDSS J135759.7+125426.4 equivalent width (in milli-Angstroms)1e-13mspect.line.eqWidthfloatnullablef_EW2[s] Flag on EW2 (1)meta.codecharl_loge2Limit flag on loge2meta.code.errorcharloge2[-2.2/6.2]? SDSS J135759.7+125426.4 log abundancephys.abundfloatnullableEW3[19.5/194]? SDSS J135756.2+125207.7 equivalent width (in milli-Angstroms)1e-13mspect.line.eqWidthfloatnullablef_EW3[s] Flag on EW3 (1)meta.codecharl_loge3Limit flag on loge3meta.code.errorcharloge3[-2.2/6]? SDSS J135756.2+125207.7 log abundancephys.abundfloatnullableEW4[21.6/160]? SDSS J135801.4+125105.2 equivalent width (in milli-Angstroms)1e-13mspect.line.eqWidthfloatnullablef_EW4[s] Flag on EW4 (1)meta.codecharl_loge4Limit flag on loge4meta.code.errorcharloge4[-2/6.1]? SDSS J135801.4+125105.2 log abundancephys.abundfloatnullableJ/ApJ/817/41/table4Magellan/MIKE chemical abundances of Boo II starsl_[X/Fe]Limit flag on [X/Fe]meta.code.error;phys.abundcharu_[X/Fe][:] Uncertainty flag on [X/Fe]; see textmeta.code.error;phys.abundchar[X/Fe][-2.4/1.7] Log abundance relative to ironphys.abundfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeqStellar identifier code (1)meta.idintIonElement/Ion/Molecule designationphys.atmol.ionStagecharN[1/109] Number of lines used in analysismeta.numberintl_logeLimit flag on logemeta.code.errorcharloge[-2.3/6.2] Log number abundancephys.abundfloatu_loge[:] Uncertainty flag on loge; see textmeta.code.errorchare_loge[0.1/0.5]? The 1{sigma} uncertainty in logestat.errorfloatnullablel_[X/H]Limit flag on [X/H]meta.code.error;phys.abundchar[X/H][-5.1/-1.1] Log abundance relative to hydrogenphys.abund;arith.zpfloatu_[X/H][:] Uncertainty flag on [X/H]; see textmeta.code.error;phys.abundchar