J/ApJ/836/137ivo://CDS.VizieR/J/ApJ/836/137doi:10.26093/cds/vizier.18360137CDSRhode K.L.Crnojevic D.Sand D.J.Janowiecki S.Young M.D.Spekkens K.2017-12-13T18:41:48Z2017-10-25T13:21:53ZCDS support team

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

cds-question@unistra.frgalaxiesphotometryvisible-astronomysloan-photometryWe present results from WIYN pODI imaging of Lacerta I (And XXXI), a satellite dwarf galaxy discovered in the outskirts of the Andromeda galaxy (M31) in Pan-STARRS1 survey data. Our deep, wide-field g,i photometry reaches ~3mag fainter than the photometry in the Pan-STARRS1 discovery paper and allows us to trace the stellar population of Lac I beyond two half-light radii from the galaxy center. We measure a Tip of the Red Giant Branch distance for Lac I of (m-M)_0_=24.44+/-0.11mag (773+/-40kpc, or 264+/-6kpc from M31), which is consistent with the Pan-STARRS1 distance. We use a maximum-likelihood technique to derive structural properties for the galaxy, and find a half-light radius (r_h_) of 3.24+/-0.21' (728+/-47pc), ellipticity ({epsilon}) of 0.44+/-0.03, total magnitude M_V_=-11.4+/-0.3, and central surface brightness {mu}_V,0_=24.8+/-0.3mag/arcsec^2^. We find no H I emission in archival data and set a limit on Lac I's neutral gas mass-to-light ratio of M_HI_/L_V_<0.06M_{sun}_/L_{sun}_, confirming Lac I as a gas-poor dwarf spheroidal galaxy. Photometric metallicities derived from Red Giant Branch stars within 2 r_h_ yield a median [Fe/H] of -1.68+/-0.03, which is more metal-rich than the spectroscopically derived value from Martin+ (2014ApJ...793L..14M). Combining our measured magnitude with this higher metallicity estimate places Lac I closer to its expected position on the luminosity-metallicity relation for dwarf galaxies.2017ApJ...836..137Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/836/137CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toV/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012)J/ApJ/756/79 : Optical photom. in 3 Local Group dwarf galaxies (Sand+, 2012)J/ApJ/768/77 : Ultra-compact high velocity clouds from ALFALFA (Adams+, 2013)J/ApJ/779/102 : Metallicities of RGB stars in dwarf galaxies (Kirby+, 2013)J/MNRAS/435/1928 : Dwarf galaxy planes in Local Group (Pawlowski+, 2013)J/A+A/585/A41 : EBHIS spectra and HI column density maps (Winkel+, 2016)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/836/137https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/836/137http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/836/137https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/836/137https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/836/137http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/836/137GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/836/137/table1 (Photometry of resolved stars in the WIYN pODI images of Lac I (And XXXI))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/836/137/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/836/137/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/836/137/table1?GETtext/xml+votable180.050000true344.372541.45803810.0055555555555555566/13720https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/836/137?format=asciiOpticaldefaultJ/ApJ/836/137/table1Photometry of resolved stars in the WIYN pODI images of Lac I (And XXXI)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeqSequential running numbermeta.id;meta.mainintRAJ2000Right Ascension in decimal degrees (J2000)degpos.eq.ra;meta.mainindexedDEJ2000Declination in decimal degrees (J2000)degpos.eq.dec;meta.mainindexedg0mag[13/27] Calibrated, dereddened WIYN/pODI g band magnitude in SDSS systemmagphot.mag;em.opt.Bfloate_g0mag[0/0.4] Uncertainty (instrumental) in g0magmagstat.error;phot.magfloatAg[0.3/0.6] Calculated Galactic extinction, g magmagphys.absorption.gal;meta.modelledfloati0mag[13/26.2] Calibrated, dereddened WIYN/pODI i band magnitude in SDSS systemmagphot.mag;em.opt.Ifloate_i0mag[0/0.4] Uncertainty (instrumental) in i0magmagstat.error;phot.magfloatAi[0.1/0.3] Calculated Galactic extinction, i magmagphys.absorption.gal;meta.modelledfloat