J/ApJ/897/183ivo://CDS.VizieR/J/ApJ/897/183doi:10.26093/cds/vizier.18970183CDSHansen T.T.Marshall J.L.Simon J.D.Li T.S.Bernstein R.A.Pace A.B.,Ferguson P.Nagasawa D.Q.Kuehn K.Carollo D.Geha M.James D.,Walker A.Diehl H.T.Aguena M.Allam S.Avila S.Bertin E.Brooks D.,Buckley-Geer E.Burke D.L.Rosell A.C.Kind M.C.Carretero J.,Costanzi M.Da Costa L.N.Desai S.De Vicente J.Doel P.Eckert K.,Eifler T.F.Everett S.Ferrero I.Frieman J.Garcia-Bellido J.,Gaztanaga E.Gerdes D.W.Gruen D.Gruendl R.A.Gschwend J.,Gutierrez G.Hinton S.R.Hollowood D.L.Honscheid K.Kuropatkin N.,Maia M.A.G.March M.Miquel R.Palmese A.Paz-Chinchon F.Plazas A.A.,Sanchez E.Santiago B.Scarpine V.Serrano S.Smith M.Soares-Santos M.Suchyta E.Swanson M.E.C.Tarle G.Varga T.N.Wilkinson R.2022-03-15T04:18:06Z2021-10-15T07:12:17ZCDS support team

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

cds-question@unistra.frgalaxiespeculiar-variable-starschemical-abundancesvisible-astronomyWe present a detailed abundance analysis of the three brightest member stars at the top of the giant branch of the ultrafaint dwarf (UFD) galaxy GrusII. All stars exhibit a higher than expected [Mg/Ca] ratio compared to metal-poor stars in other UFD galaxies and in the Milky Way (MW) halo. Nucleosynthesis in high-mass (>=20M{sun}) core-collapse supernovae has been shown to create this signature. The abundances of this small sample (three) stars suggests the chemical enrichment of GrusII could have occurred through substantial high-mass stellar evolution, and is consistent with the framework of a top-heavy initial mass function. However, with only three stars it cannot be ruled out that the abundance pattern is the result of a stochastic chemical enrichment at early times in the galaxy. The most metal-rich of the three stars also possesses a small enhancement in rapid neutron-capture (r-process) elements. The abundance pattern of the r-process elements in this star matches the scaled r-process pattern of the solar system and r-process enhanced stars in other dwarf galaxies and in the MW halo, hinting at a common origin for these elements across a range of environments. All current proposed astrophysical sites of r-process element production are associated with high- mass stars, thus the possible top-heavy initial mass function of GrusII would increase the likelihood of any of these events occurring. The time delay between the {alpha} and r-process element enrichment of the galaxy favors a neutron star merger as the origin of the r-process elements in GrusII.2020ApJ...897..183Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/897/183CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/357 : The Dark Energy Survey (DES): Data Release 1 (Abbott+, 2018)J/A+A/439/129 : HERES II. Spectroscopic analysis (Barklem+, 2005)J/ApJ/655/492 : Equivalent widths of 26 metal-poor stars (Aoki+, 2007)J/A+A/512/A54 : Teff and Fbol from Infrared Flux Method (Casagrande+, 2010)J/ApJ/708/560 : Spectroscopy of UMa II and Coma Ber (Frebel+, 2010)J/ApJ/724/341 : Nucleosynthesis of massive metal-free stars (Heger+, 2010)J/ApJ/723/1632 : Abundance spreads in Bootes I and Segue 1 (Norris+, 2010)J/AJ/141/175 : Abundances in M15 RGB/RHB stars (Sobeck+, 2011)J/ApJ/769/57 : Equivalent widths of metal-poor stars (Frebel+, 2013)J/ApJ/763/61 : Abundances of 7 red giant members of BootesI (Gilmore+, 2013)J/ApJ/778/149 : Abundances for 3 stars in Sgr dSph (McWilliam+, 2013)J/ApJ/786/74 : EW measurements of 6 Segue 1 red giants (Frebel+, 2014)J/A+A/562/A146 : Chemical abundances of 8 metal-poor stars (Ishigaki+, 2014)J/ApJ/797/21 : Carbon-enhanced metal-poor stars (Placco+, 2014)J/MNRAS/440/2665 : SDSS J021933.13+200830.2 spectroscopy (Roederer+, 2014)J/AJ/147/136 : Stars low metal abundance. VI. Abundances (Roederer+, 2014)J/ApJ/826/110 : Boo-127 and Boo-980 high-resolution spectra (Frebel+, 2016)J/ApJ/830/93 : Abundances of Ret II brightest red giant members (Ji+, 2016)J/ApJ/817/41 : Abundances of 4 metal-poor red giants in BooII (Ji+, 2016)J/AJ/151/82 : 4 brightest red giants in UFD galaxy Ret 2 (Roederer+, 2016)J/ApJ/838/44 : Abundances of the brightest member of Tuc III (Hansen+, 2017)J/ApJ/857/74 : Abundances of 7 new member stars in Tucana II (Chiti+, 2018)J/ApJ/858/92 : RPA Southern Pilot Search of 107 Stars (Hansen+, 2018)J/ApJ/866/22 : Spectroscopic analysis of Tuc III stream (Li+, 2018)J/ApJ/852/99 : Abundances of 3 metal-poor stars Horologium I (Nagasawa+,2018)J/ApJ/882/40 : Lanthanide fraction distrib. of metal-poor stars (Ji+, 2019)J/ApJ/870/83 : Abundances in ultra-faint dwarf gal. GruI & TriII (Ji+, 2019)J/ApJ/882/177 : Abundances of 4 member stars of Tucana III (Marshall+, 2019)J/ApJ/875/77 : Proper motions of MW satellites with Gaia & DES (Pace+, 2019)J/ApJ/889/27 : Abundances of 11 stars in Carina II and III (Ji+, 2020)J/ApJ/892/137 : Spectroscopy of Grus II, Tuc IV and Tuc V (Simon+, 2020)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/897/183https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/897/183http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/897/183https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/897/183https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/897/183http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/897/183GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/897/183/table1 (Observing Log)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/897/183/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/897/183/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/897/183/table1?GETtext/xml+votable180.050000true331.0995833-46.61735560.0055555555555555566/46621https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/897/183?format=asciiOpticaldefaultJ/ApJ/897/183/table1Observing LogS/N4100[3/12] Signal-to-noise ration at 4100{AA}stat.snrintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar identifiermeta.id;meta.maincharNobsNumber of data observed for this starmeta.numberintnullableRAJ2000[22] Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000[46] Degree of declination (J2000)pos.eq.dec;meta.maingmag[17.5/19.4] g-band magnitudemagphot.mag;em.opt.Vfloatrmag[16.7/18.9]? r-band magnitudemagphot.mag;em.opt.Rfloatnullableimag[16.4/18.7]? i-band magnitudemagphot.mag;em.opt.Ifloatnullablezmag[16.2/18.6]? z-band magnitudemagphot.mag;em.opt.IfloatnullableMJD[57605/58433] Modified Juliand Date of observation; MJD-2400000.5dtime.epochintTexpExposure time for each observationstime.duration;obs.exposurecharf_S/N4100[a] Flag means S/N of the combined spectrum per pixelmeta.codecharS/N5500[5/32] Signal-to-noise ration at 5500{AA}stat.snrintf_S/N5500[a] Flag means S/N of the combined spectrum per pixelmeta.codecharRVel[-107/77] Heliocentric radial velocitykm/sspect.dopplerVeloc;pos.heliocentricfloate_RVel[0.6/1.1] Error on RVelkm/sstat.error;spect.dopplerVelocfloatMembMember? Yes or Nometa.code.membercharIDIdentifier used in this workmeta.idcharprimaryAbundInteractive Plotmeta.ref.urlcharSimbadSimbad column added by the CDSmeta.ref.urlcharJ/ApJ/897/183/abundEW and atomic datarecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDStellar IDmeta.id;meta.maincharSpeciesSpeciesmeta.notecharlambdaWavelength0.1nmem.wlfloatExPotExcitation potentialeVphys.atmol.excitationfloatloggfLog of the oscillator strengthphys.atmol.oscStrengthfloatEWEquivalent width of species line1e-13mspect.line.eqWidthfloate_EWUncertainty in EW1e-13mstat.error;spect.line.eqWidthfloat[Abd]Abundance, logphys.abundfloat