J/ApJ/895/78ivo://CDS.VizieR/J/ApJ/895/78doi:10.26093/cds/vizier.18950078CDSWojno J.Gilbert K.M.Kirby E.N.Escala I.Beaton R.L.Tollerud E.J.,Majewski S.R.Guhathakurta P.2022-03-15T06:34:41Z2021-10-06T12:14:35ZCDS support team

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

cds-question@unistra.frgiant-starsgalaxiesmetallicityvisible-astronomyspectroscopyWe present chemical abundances of red giant branch (RGB) stars in the dwarf spheroidal (dSph) satellite system of Andromeda (M31), using spectral synthesis of medium-resolution (R~6000) spectra obtained with the KeckII telescope and Deep Imaging Multi-Object Spectrometer spectrograph via the Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo survey. We coadd stars according to their similarity in photometric metallicity or effective temperature to obtain a signal-to-noise ratio (S/N) high enough to measure average [Fe/H] and [{alpha}/Fe] abundances. We validate our method using high S/N spectra of RGB stars in Milky Way globular clusters, as well as deep observations for a subset of the M31 dSphs in our sample. For this set of validation coadds, we compare the weighted average abundance of the individual stars with the abundance determined from the coadd. We present individual and coadded measurements of [Fe/H] and [{alpha}/Fe] for stars in 10 M31 dSphs, including the first [{alpha}/Fe] measurements for And IX, XIV, XV, and XVIII. These fainter, less massive dSphs show declining [{alpha}/Fe] relative to [Fe/H], implying an extended star formation history (SFH). In addition, these dSphs also follow the same mass-metallicity relation found in other Local Group satellites. The conclusions we infer from coadded spectra agree with those from previous measurements in brighter M31 dSphs with individual abundance measurements, as well as conclusions from photometric studies. These abundances greatly increase the number of spectroscopic measurements of the chemical composition of M31's less massive dwarf satellites, which are crucial to understanding their SFH and interaction with the M31 system.2020ApJ...895...78Whttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/895/78CatalogResearchIsServedByTAP VizieR generic servicerelated-toII/267 : The SDSS Photometric Catalog, Release 4 (Adelman-McCarthy+, 2006)I/345 : Gaia DR2 (Gaia Collaboration, 2018)J/A+A/364/102 : Abundances of field BHB star candidates (Kinman+, 2000)J/AJ/125/1352 : Ursa Minor dSph M,T2, DDO51 photometry (Palma+, 2003)J/ApJ/663/960 : Radial velocities of Leo I stars (Sohn+, 2007)J/ApJ/682/1217 : Abundances in red giants in 7 globular clusters (Kirby+, 2008)J/ApJ/705/328 : Abundance measurements in Sculptor dSph (Kirby+, 2009)J/ApJS/191/352 : Abundances in stars Milky Way dwarf satellites (Kirby+, 2010)J/A+A/523/A17 : Individual stars in Fornax dSph center (Letarte+, 2010)J/ApJ/753/64 : Detailed abundances for 97 metal-poor stars (Ishigaki+, 2012)J/AJ/144/4 : Properties dwarf galaxies in Local Group (McConnachie+, 2012)J/ApJ/752/45 : SPLASH: Stellar spectroscopy M31 satellites (Tollerud+, 2012)J/ApJ/768/172 : Kinematic analysis of red giant in M31 dSphs (Collins+, 2013)J/ApJ/779/102 : Metallicities of RGB stars in dwarf galaxies (Kirby+, 2013)J/AJ/146/86 : Cosmicflows-2 catalog (Tully+, 2013)J/ApJ/767/134 : Abundances of red giant stars in UFD galaxies (Vargas+, 2013)J/ApJ/790/73 : Fe & alpha abundance of RGBs in M31 satellites (Vargas+, 2014)J/ApJ/819/135 : Lithium-rich giants in globular clusters (Kirby+, 2016)J/ApJ/883/128 : alpha & Fe abundances in giant stellar stream (Gilbert+, 2019)J/ApJ/889/177 : RGB abundances in disk, stream & halo of M31 (Escala+, 2020)J/AJ/159/46 : Elemental abund. of 416 stars in 5 dSphs of M31 (Kirby+,2020)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/895/78https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/895/78http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/895/78https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/895/78https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/895/78http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/895/78GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/ApJ/895/78/table5Excerpt of measured [Fe/H] and [{alpha}/Fe] from our coadded spectrarecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBinBin type; [Fe/H] or Teffphys.abund.FecharCoaddCoadd type; science or validationmeta.codecharMaskMask namemeta.notecharSlitSlit listmeta.notechar[Fe/H][-4.4/-0.92] Metallicitylog(Sun)phys.abund.Zfloate_[Fe/H][0.1/0.35] Uncertainty in [Fe/H]log(Sun)stat.error;phys.abund.Fefloat[a/H][-0.78/1.2] log {alpha}/Fe abundance ratiolog(Sun)phys.abund;arith.ratiofloate_[a/H][0.09/0.9] Uncertainty in [a/H]log(Sun)stat.error;phys.abundfloat