J/A+A/487/131ivo://CDS.VizieR/J/A+A/487/131doi:10.26093/cds/vizier.34870131CDSCioni M.-R.L.Irwin M.Ferguson A.M.N.McConnachie A.Conn B.C.,Huxor A.Ibata R.Lewis G.Tanvir N.2019-07-26T16:16:08Z2008-09-21T08:33:43ZCDS support team

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

cds-question@unistra.frgalaxiesvariable-starsinfrared-photometryWide-field JHKs near-infrared observations covering an area of 1.8x1.8deg^2^ centred on M33 were obtained using WFCAM at UKIRT. These data show a large population of intermediate-age asymptotic giant branch stars (AGB). We have used both C-type and M-type AGB stars to determine spatial variations in metallicity and mean age across the galaxy. We distinguished between C-type and M-type AGB stars from their location in the colour-magnitude diagram (J-Ks, Ks). The distribution of these stars is supported by a cross-identification between our sample and a catalogue of optically confirmed, long-period variable stars, as well as with the list of sources detected by Spitzer in the mid-infrared. We calculated the C/M ratio and the orientation of the galaxy in the sky, and compared the Ks magnitude distribution with theoretical distributions spanning a range of metallicities and star formation rates (SFRs). The C/M ratio surface map confirms a metallicity gradient in the galaxy corresponding to a spread in [Fe/H]=0.6dex with substructures in the inner and outer galaxy. Magnitude and colour variations suggest orientation and extinction effects on the galaxy disc. Maps showing the distribution of mean age and metallicity obtained from the Ks method suggest that: the outer galaxy disc/halo is metal poorer than the nuclear region and metal-rich clumps in the inner galaxy change location with time. The average outer ring and nuclear stellar population is ~6Gyr old while central regions are a few Gyr younger.2008A&A...487..131Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/487/131CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/121/870 : BVI photometry of variables in M33 (Macri+, 2001)J/AJ/132/1361 : RR Lyrae variables in M33 (Sarajedini+, 2006)J/MNRAS/371/1405 : Variables in M33 (Hartman+, 2006)J/ApJ/664/850 : Spitzer M33 variables (McQuinn+, 2007)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/487/131https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/487/131http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/487/131https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/487/131https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/487/131http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/487/131GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/487/131/table1 (Near-IR magnitudes for Long-Period Variables (LPVs))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/487/131/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/487/131/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/487/131/table1?GETtext/xml+votable180.050000true23.9141119431.014138890.005555555555555556Cone search capability for table J/A+A/487/131/table2 (Near-IR magnitudes for stars observed by Spitzer)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/487/131/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/487/131/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/487/131/table2?GETtext/xml+votable180.050000true23.0078630.434171940.0055555555555555566/2154-2155 2240-22412.381800341673347e-19 2.821731604724377e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/487/131?format=asciiInfrareddefaultJ/A+A/487/131/table1Near-IR magnitudes for Long-Period Variables (LPVs)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right ascension in decimal degrees (J2000.0)degpos.eq.ra;meta.mainDEJ2000Declination in decimal degrees (J2000.0)degpos.eq.dec;meta.maini'magSDSS i' magnitudemagphot.mag;em.opt.Ifloatr'-i'SDSS r'-i' colour indexmagphot.color;em.opt.R;em.opt.IfloatJmagDereddened Johnson J magnitude (G1)magphot.mag;em.IR.JfloatHmagDereddened Johnson H magnitude (G1)magphot.mag;em.IR.HfloatKsmagDereddened Johnson Ks magnitude (G1)magphot.mag;em.IR.KfloatHBS2006Data from Hartman, Bersier, Stanek et al. 2006, Cat. J/MNRAS/371/1405meta.ref.urlcharJ/A+A/487/131/table2Near-IR magnitudes for stars observed by SpitzerrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSSTM3307Spitzer-ID (JHHMMSS.SS+DDMMSS.s)meta.id;meta.maincharRAJ2000Right ascension in decimal degrees (J2000.0)degpos.eq.ra;meta.mainDEJ2000Declination (J2000.0)degpos.eq.dec;meta.mainJmagDereddened Johnson J magnitude (G1)magphot.mag;em.IR.JfloatHmagDereddened Johnson H magnitude (G1)magphot.mag;em.IR.HfloatKsmagDereddened Johnson Ks magnitude (G1)magphot.mag;em.IR.Kfloat