J/A+A/618/A156ivo://CDS.VizieR/J/A+A/618/A156doi:10.26093/cds/vizier.36180156CDSSaglia R.Opitsch M.Fabricius M.H.Bender R.Blana M.Gerhard O.2022-11-22T15:28:22Z2018-10-30T06:40:21ZCDS support team

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

cds-question@unistra.frgalaxiesstellar-populationsspectroscopyWe continue the analysis of the data set of our spectroscopic observation campaign of M31, whose ultimate goal is to provide an understanding of the three-dimensional structure of the bulge, its formation history, and composition in terms of a classical bulge, boxy-peanut bulge, and bar contributions. We derive simple stellar population (SSP) properties, such as age metallicity and alpha-element overabundance, from the measurement of Lick/IDS absorption line indices. We describe their two-dimensional maps taking into account the dust distribution in M31. We found 80% of the values of our age measurements are larger than 10Gyr. The central 100-arcsec of M31 are dominated by the stars of the classical bulge of M31. These stars are old (11-13Gyr), metal-rich (as high as [Z/H]~0.35dex) at the center with a negative gradient outward and enhanced in alpha-elements ([alpha/Fe]~0.28+/-0.01dex). The bar stands out in the metallicity map, where an almost solar value of [Z/H] (~0.02+/-0.01dex) with no gradient is observed along the bar position angle (55.7{deg}) out to 600 arcsec from the center. In contrast, no signature of the bar is seen in the age and [alpha/Fe] maps, which are approximately axisymmetric, delivering a mean age and overabundance for the bar and boxy-peanut bulge of 10-13Gyr and 0.25-0.27dex, respectively. The boxy-peanut bulge has almost solar metallicity (-0.04+/-0.01dex). The mass-to-light ratio of the three components is approximately constant at M/LV~4.4-4.7M_{sun}_/L_{sun}_. The disk component at larger distances is made of a mixture of stars, as young as 3-4Gyr, with solar metallicity and smaller M/LV (~3+/-0.1M_{sun}_/L_{sun}_). We propose a two-phase formation scenario for the inner region of M31, where most of the stars of the classical bulge come into place together with a proto-disk, where a bar develops and quickly transforms it into a boxy-peanut bulge. Star formation continues in the bulge region, producing stars younger than 10Gyr, in particular along the bar, thereby enhancing its metallicity. The disk component appears to build up on longer timescales.2018A&A...618A.156Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/618/A156CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/MNRAS/459/2262 : Maps of dust distribution in M31 bulge (Dong+, 2016)J/MNRAS/473/4130 : M31 center emission-line point-like sources (Martin+, 2018)J/A+A/611/A38 : Hints for a bar in M31 kinematics and morphologyhttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/618/A156https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/618/A156http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/618/A156https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/618/A156https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/618/A156http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/618/A156GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/618/A156/table5 (Coordinates of the Voronoi bins)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/618/A156/table5?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/618/A156/table5?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/618/A156/table5?GETtext/xml+votable180.050000true10.684291741.270550.0055555555555555566/2623 2708-2709https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/618/A156?format=asciidefaultJ/A+A/618/A156/table6Lick indicespapIDisplay the Stellar and nebular data from Paper I (Opitsch et al., 2016, cat. J/A+A/611/A38)meta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBin[0/6472] Number of the Voronoi binmeta.id;meta.mainintHbLick index H{beta}0.1nmspect.indexfloate_HbError on H{beta}0.1nmstat.errorfloatMgbLick index Mgb0.1nmmeta.code;spect.indexfloate_MgbError on Mgb0.1nmstat.errorfloatFe5015Lick index Fe50150.1nmmeta.code;spect.indexfloate_Fe5015Error on Fe50150.1nmstat.errorfloatFe5270Lick index Fe52700.1nmmeta.code;spect.indexfloate_Fe5270Error on Fe52700.1nmstat.errorfloatFe5335Lick index Fe53350.1nmmeta.code;spect.indexfloate_Fe5335Error on Fe53350.1nmstat.errorfloatFe5406Lick index Fe54060.1nmmeta.code;spect.indexfloate_Fe5406Error on Fe54060.1nmstat.errorfloatJ/A+A/618/A156/table7SSP parametersAgeSSP ageGyrtime.agefloatML/V80SSP M/L_V_ at Age80%solMass/solLumphys.composition.massLightRatiofloatpapIDisplay the Stellar and nebular data from Paper I (Opitsch et al., 2016, cat. J/A+A/611/A38)meta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBin[0/6472] Number of the Voronoi binmeta.id;meta.mainintb_AgeSSP minimum AgeGyrtime.age;stat.minfloatB_AgeSSP maximum AgeGyrtime.age;stat.maxfloatAge80SSP Age80%Gyrtime.agefloat[Z/H]SSP [Z/H]log(Sun)phys.abund.Zfloatb_[Z/H]SSP minimum [Z/H]log(Sun)src.redshift;stat.minfloatB_[Z/H]SSP maximum [Z/H]log(Sun)src.redshift;stat.maxfloat[alpha/Fe]SSP [alpha/Fe]log(Sun)phys.abundfloatb_[alpha/Fe]SSP minimum [alpha/Fe]log(Sun)phys.abund;stat.minfloatB_[alpha/Fe]SSP maximum [alpha/Fe]log(Sun)phys.abund;stat.maxfloatM/LVSSP M/L_V_solMass/solLumphys.composition.massLightRatiofloatb_M/LVSSP minimum M/L_V_solMass/solLumphys.composition.massLightRatio;stat.minfloatB_M/LVSSP maximum M/L_V_solMass/solLumphys.composition.massLightRatio;stat.maxfloatJ/A+A/618/A156/table5Coordinates of the Voronoi binsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBin[0/6472] Number of the Voronoi binmeta.id;meta.mainintxposCoordinate, centered on nucleus, +x points Westarcsecpos.cartesian.x;instr.detdoubleyposCoordinate, centered on nucleus, +y points Northarcsecpos.cartesian.y;instr.detdouble_RAPosition from J/A+A/611/A38 (right ascension part)degpos.eq.ra;meta.mainindexed_DEPosition from J/A+A/611/A38 (declination part)degpos.eq.dec;meta.mainindexed