J/ApJ/883/128ivo://CDS.VizieR/J/ApJ/883/128doi:10.26093/cds/vizier.18830128CDSGilbert K.M.Kirby E.N.Escala I.Wojno J.Kalirai J.S.Guhathakurta P.2022-05-05T13:59:21Z2021-03-24T13:58:37ZCDS support team

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

cds-question@unistra.frchemical-abundancesvisible-astronomyspectroscopygiant-starsradial-velocitygalaxiesWe present the first measurements of [Fe/H] and [{alpha}/Fe] abundances, obtained using spectral synthesis modeling, for red giant branch stars in M31's giant stellar stream (GSS). The spectroscopic observations, obtained at a projected distance of 17kpc from M31's center, yielded 61 stars with [Fe/H] measurements, including 21 stars with [{alpha}/Fe] measurements, from 112 targets identified as M31 stars. The [Fe/H] measurements confirm the expectation from photometric metallicity estimates that stars in this region of M31's halo are relatively metal rich compared to stars in the Milky Way's inner halo: more than half the stars in the field, including those not associated with kinematically identified substructure, have [Fe/H] abundances >-1.0. The stars in this field are {alpha}-enhanced at lower metallicities, while [{alpha}/Fe] decreases with increasing [Fe/H] above metallicities of [Fe/H]>~-0.9. Three kinematical components have been previously identified in this field: the GSS, a second kinematically cold feature of unknown origin, and M31's kinematically hot halo. We compare probabilistic [Fe/H] and [{alpha}/Fe] distribution functions for each of the components. The GSS and the second kinematically cold feature have very similar abundance distributions, while the halo component is more metal poor. Although the current sample sizes are small, a comparison of the abundances of stars in the GSS field with abundances of M31 halo and dSph stars from the literature indicate that the progenitor of the stream was likely more massive, and experienced a higher efficiency of star formation, than M31's existing dSphs or the dEs NGC147 and NGC185.2019ApJ...883..128Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/883/128CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/183 : UBVRI Photometric Standards (Landolt 1992)J/MNRAS/327/918 : CaII in extragalactic red giants (Tolstoy+, 2001)J/A+A/416/1117 : Abundances in the early Galaxy (Cayrel+, 2004)J/AJ/128/1177 : Galactic stellar abundances (Venn+, 2004)J/A+A/439/129 : HERES II. Spectroscopic analysis (Barklem+, 2005)J/ApJ/663/960 : Radial velocities of Leo I stars (Sohn+, 2007)J/MNRAS/383/183 : CaII triplet of RGB from VLT/FLAMES obs. (Battaglia+, 2008)J/MNRAS/390/1437 : Stellar streams in Andromeda (M31) (Chapman+, 2008)J/ApJ/682/1217 : Abundances in red giants in 7 GCs (Kirby+, 2008)J/ApJ/681/1524 : Detailed abundances for 28 metal-poor stars (Lai+, 2008)J/A+A/480/379 : Abundances of 59 red giants in LMC (Pompeia+, 2008)J/ApJ/705/328 : Abundance measurements in Sculptor dSph (Kirby+, 2009)J/AJ/137/272 : Space velocities orbits in the MW halo (Roederer+ 2009)J/ApJ/719/931 : Chemical evolution of the UMi dSph (Cohen+, 2010)J/AN/331/474 : Abundances of metal-poor stars (Frebel, 2010)J/ApJS/191/352 : Abundances in stars of MW dwarf satellites (Kirby+, 2010)J/A+A/544/A73 : BVI photometry of Fornax dSph galaxy (de Boer+, 2012)J/ApJ/761/33 : Chemical data of 89 stars in the LMC disk (Lapenna+, 2012)J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012)J/ApJ/752/45 : SPLASH: Stellar sp. of M31 satellites (Tollerud+, 2012)J/ApJ/779/102 : Metallicities of RGB stars in dwarf galaxies (Kirby+, 2013)J/A+A/560/A44 : Abundances of LMC bar & disk stars (Van der Swaelmen+, 2013)J/ApJ/790/73 : Abundances of RGBs in M31 satellites (Vargas+, 2014)J/ApJ/789/147 : Star formation histories of LG dwarf galaxies (Weisz+, 2014)J/ApJ/798/77 : Metallicity of RGB stars in 6 M31 dwarf galaxies (Ho+, 2015)J/ApJ/801/125 : Carbon in red giants in GCs and dSph galaxies (Kirby+, 2015)J/MNRAS/455/199 : CaII triplet in red giant spectra (Da Costa, 2016)J/A+A/605/A46 : Sgr dSph nucleus stars chemical abund. (Mucciarelli+, 2017)J/ApJ/846/145 : PHAT. XIX. Formation history of M31 disk (Williams+, 2017)J/ApJ/868/55 : M31 halo. II. PAndAS (McConnachie+, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/883/128https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/883/128http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/883/128https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/883/128https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/883/128http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/883/128GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/883/128/table2 (Parameters of stars with abundance measurements)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/883/128/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/883/128/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/883/128/table2?GETtext/xml+votable180.050000true10.877583340.10955560.0055555555555555566/2620 2622https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/883/128?format=asciiOpticaldefaultJ/ApJ/883/128/table2Parameters of stars with abundance measurementsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintName[2070316/2075349] Object identifiermeta.id;meta.mainintRAJ2000[0] Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000[39/40] Degree of Declination (J2000)pos.eq.dec;meta.mainSN[5.6/21.5] Signal-to-Noise0.1nm**-1stat.snrfloatHRV[-597.1/-207.4] Heliocentric radial velocitykm/sspect.dopplerVeloc;pos.heliocentricfloatTeff[3774/4966] Effective temperatureKphys.temperature.effectiveinte_Teff[18/87] Uncertainty in TeffKstat.error;phys.temperature.effectiveintlog(g)[0.5/1.5] log surface gravitylog(cm.s**-2)phys.gravityfloat[Fe/H][-2.13/-0.03] Metallicity (1)log(Sun)phys.abund.Fefloate_[Fe/H][0.1/0.4] Uncertainty in [Fe/H]log(Sun)stat.error;phys.abund.Fefloat[a/Fe][0.09/0.8]? log {alpha} to Fe number abundance (1)log(Sun)phys.abundfloatnullablee_[a/Fe][0.18/0.4]? Uncertainty in [a/Fe]log(Sun)stat.error;phys.abundfloatnullableSimbadSimbad column added by the CDSmeta.ref.urlchar