J/A+A/533/A91ivo://CDS.VizieR/J/A+A/533/A91doi:10.26093/cds/vizier.35330091CDSGrossi M.Hwang N.Corbelli E.Giovanard C.Okamoto S.Arimoto N.2018-02-02T10:34:12Z2011-09-07T14:05:04ZCDS support team

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

cds-question@unistra.frgalaxiesphotometryccd-photometryWe present Subaru/Suprime-Cam deep V and I imaging of seven fields in the outer regions of M33. Our aim is to search for stellar structures corresponding to extended HI clouds found in a recent 21-cm survey of the galaxy. Three fields probe a large HI complex to the southeastern (SE) side of the galaxy. An additional three fields cover the northwestern (NW) side of the galaxy along the HI warp. A final target field was chosen further north, at a projected distance of approximately 25kpc, to study part of the large stellar plume recently discovered around M33. We analyse the stellar population at R>10kpc by means of V, I colour magnitude diagrams reaching the red clump. We constrain the age and metallicity of the different stellar populations, search for density enhancements that correspond to the HI features, and investigate the radial surface distribution of the stars. We find evolved stellar populations in all fields out to 120' (~30kpc), while a diffuse population of young stars (~200Myr) is detected out to a galactocentric radius of 15kpc. The mean metallicity in the southern fields remains approximately constant at [M/H]=-0.7 beyond the edge of the optical disc, from 40' out to 80'. Along the northern fields probing the outer HI disc, we also find a metallicity of [M/H]=-0.7 between 35' and 70' from the centre, which decreases to [M/H]=-1.0 at larger angular radii out to 120'. In the northernmost field, outside the disc extent, the stellar population of the large stellar plume possibly related to a M33-M31 interaction is on average more metal-poor ([M/H]=-1.3) and older (>6Gyr). An exponential disc with a large scale-length (~7kpc) fits well the average distribution of stars detected in both the SE and NW regions from a galactocentric distance of 11kpc out to 30kpc. The stellar disc extends beyond the HI disc. The stellar distribution at large radii is disturbed and, although there is no clear correlation between the stellar substructures and the location of the HI clouds, this gives evidence of tidal interaction or accretion events.2011A&A...533A..91Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/533/A91CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/110/2739 : H-alpha emitting regions in M33 (Calzetti+ 1995)J/A+A/366/498 : VI photometry of M33 star clusters (Chandar+, 2001)J/A+A/426/11 : XMM-Newton survey of M33 (Pietsch+, 2004)J/A+A/476/1161 : Spitzer photometry of M33 (Verley+, 2007)J/ApJ/664/850 : Spitzer observations of stars in M33 (McQuinn+, 2007)J/AJ/128/224 : VI photometry in M33 outer regions (Tiede+, 2004)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/533/A91https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/533/A91http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/533/A91https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/533/A91https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/533/A91http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/533/A91GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/533/A91/table1 (Central coordinates of the target fields observed with Subaru/Suprime-Cam)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/533/A91/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/533/A91/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/533/A91/table1?GETtext/xml+votable180.050000true24.06529.6750.005555555555555556Cone search capability for table J/A+A/533/A91/catalog (Positions and magnitudes of the stars observed in the 8 fields)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/533/A91/catalog?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/533/A91/catalog?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/533/A91/catalog?GETtext/xml+votable180.050000true28.26188530.434686940.0055555555555555565/538 560 6/2160 2244 22462.367228618189496e-19 3.852589004194616e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/533/A91?format=asciiOpticaldefaultJ/A+A/533/A91/table1Central coordinates of the target fields observed with Subaru/Suprime-CamrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFldField designationmeta.id;meta.maincharprimaryRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainr? Corresponding projected distance from M33 (for distance(M33) = 840 kpc)kpcpos.distancefloatnullableVseeSeeing in V imagearcsecinstr.obsty.seeingfloatIseeSeeing in I imagearcsecinstr.obsty.seeingfloatAVExtinction value adopted for the fieldmagphys.absorptionfloatFileNameName of the file with field photometrymeta.id;phot;meta.filecharJ/A+A/533/A91/catalogPositions and magnitudes of the stars observed in the 8 fieldse_ImagError on I magnitudemagstat.error;phot.mag;em.opt.IfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFldField nameobs.fieldcharVxposX coordinate on V framepixpos.cartesian.x;instr.detdoubleVyposY coordinate on V framepixpos.cartesian.y;instr.detdoubleIxposX coordinate on I framepixpos.cartesian.x;instr.detdoubleIyposY coordinate on I framepixpos.cartesian.y;instr.detdoubleRAJ2000Right ascension (J2000.0)degpos.eq.ra;meta.mainDEJ2000Declination (J2000.0)degpos.eq.dec;meta.mainVmagV magnitude (1)magphot.mag;em.opt.Vfloate_VmagError on V magnitudemagstat.error;phot.mag;em.opt.VfloatImagI magnitude (1)magphot.mag;em.opt.Ifloat