vmc – the vista survey of the magellanic system filethe vista survey of the magellanic system m....
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VMC–theVISTAsurveyoftheMagellanicSystem
Metallicityofstellarpopula<onsMo<onofstellarpopula<ons
DrMaria‐RosaCioni
ESO spectroscopic survey workshop ESO-Garching, Germany, 9-10 March 2009
(Gal-Exgal survey)
TheVISTAsurveyoftheMagellanicSystem
M.Cioni,K.Bekki,G.Clemen<ni,W.deBlok,J.Emerson,C.Evans,R.deGrijs,B.Gibson,L.Girardi,M.Groenewegen,V.Ivanov,M.Marconi,C.Mastropietro,B.Moore,R.Napiwotzki,T.Naylor,J.Oliveira,V.Ripepi,J.vanLoon,M.Wilkinson,P.Wood
UnitedKingdom,Italy,Belgium,Chile,France,Switzerland,SouthAfrica,Australia http://star.herts.ac.uk/~mcioni/vmc/
Theteam
Themostsensi<venear‐IRsurveyacrosstheLMC,SMC,BridgeandpartoftheStream
ESO Public Survey 2009-2014
1.5 deg2
FOV
4m Telescope
≈180deg23filters‐YJKs15epochs(12inKSand3inYJ;oncesimultaneouscolours)S/N=10at:Y=21.9,J=21.4,Ks=20.3(Ks≈19singleepoch)Seeing0.8arcsec–averageSpa<alresolu<on0.34pix/arcsec(0.51arcsecinstrumentPSF)Servicemodeobserving1840hours/240nights
http://star.herts.ac.uk/~mcioni/vmc/
0.ObservetheMagellanicSystem
I.Derivethespa<allyresolvedSFH
Synthe<cdiagramofatypicalLMCstellarfieldasexpectedfromVMCdata.
Thisfieldcovers1VISTAdetector!
Accuracy:metallicity0.1dexandage20%in0.1deg2
Kerberetal2009
http://star.herts.ac.uk/~mcioni/vmc/
S/N=10
RRLyraestarsareexcellentdistanceindicatorsinthenear‐IR
Firstapplica<ontotheLMCbartoderivetheLMCdistance(Szewczyketal2008)–0.2kpcaccuracy
ThestructureoftheMagellanicSystemwillbemeasuredusingCepheidvariables,theredclumpluminosity,the<poftheredgiantbrach,etc.
II.Tracethe3Dstructureasafunc<onof<me
http://star.herts.ac.uk/~mcioni/vmc/
The LMC is a few kpc thick and the SMC up to 20 kpc
III.IV.V.VI.VII.VIII....
Stellar Clusters and other sub-structures Planetary Nebula and other emission line objects Obscured massive stars and pre-MS stars of a few MSun The differential proper motion The distance of the Large Magellanic Cloud Simulations of the Magellanic System Etc.
A unique counterpart for existing and planned (e.g. VST) optical surveys & mid-infrared Spitzer observations
Complementary to a survey of the outer region (8-20 kpc); the VISTA-VHS will cover this area (Ks≈18)
PNedetec<on The sample of PNe across the Magellanic Clouds is very incomplete
Current samples are biased to bright (young and asymmetric) PNe
Reid & Parker (2006) have doubled the number of PNe in the central 25 deg2
VMC will detect PNe from their colours; VMC spatial resolution - good
Ks includes Brγ with very little contamination by He
Brγ traces nebulae as Hα
Spectroscopic follow-up is required for confirmation
Themetallicity(iron+)asatracerofhistoryandstructure
Primordial gas is metal-poor. Enrichment is due to subsequent star formation, accretion or merging. The distribution of gas is influenced by the structure and dynamics of the host galaxy.
What is the chemical history of the Magellanic System? How and when the Bridge and Stream formed? What is the depth of the Magellanic Clouds? Are they disc galaxies with a spheroidal halo? How and when these structures formed? Etc…
Themetallicitydecreaseslinearly;aflatoutergradient? RRLyraestars,metalpoorRGBstarsandoldstellarclusterstracethesamegradientasAGBstars(outerdisc/halo?) YoungRGBstarsandyoungstellarclustersshownogradient(bareffect?)
MetallicitygradientacrosstheLMC(Cioni2009,tbs)
MetallicitygradientacrosstheSMC(Cioni2009,tbs)
Stellarclusters(youngandold),AGBstarsandRGBstarsdonotshowasignificantgradient.Bareffect? ThemetallicityisconsistentwiththatintheBridge ThemetallicityoftheSMCisthesameasthatoftheLMCat4kpc(innerdisc/outerdiscorhalotransi<on?)
AnSMCmetal‐richring?
via optical colour-magnitude diagrams Harris & Zaritsky 2004
10.6 Gy 8.7 Gy 6.3 Gy 3.9 Gy 2 Gy via magnitude distributions of AGB stars Cioni et al 2006
Propagation of star formation? Accretion of satellite? Star forming episode induced by LMC interaction? Effect of bar? α elements or oxygen enhancement?
Aviablepicture(agreement/disagreement/largeerrors/models?):
TheMagellanicCloudsexperiencedtwomajorepisodesofstarforma<on:onemanyGyragoandone2‐4Gyrago
TheoldepisodeformedtheLMCouterdisc/haloandtheSMCbar.TherecentepisodeformedtheinnerLMCdisc,theLMCbarandinducedstarforma<onintheSMCring.
TheMagellanicStreamformedoutofLMCgasintherecentepisode:[Fe/H]=‐0.6dex(Niedeveretal2008).TheMagellanicBridgeformedoutofSMCgas.
TheSMCmayhaveabulge(Subramanian&Subramaniam2009).
TheMo<onofstellarpopula<ons Theageandchemistryofgroupsofstarsarenot
sufficienttodescribetheforma<onandevolu<onofthehostgalaxy
Thedynamicalstateisneededtorecognizesub‐structuresthatshapedtheMagellanicSystem(bulge,halo,clustersvsfieldstars)
Thespacemo<onrequiresboththeradialvelocityandthetangen<alvelocity
Radialvelocityobserva<onsexistonlyforsubsetsofstarslimitedintypeorloca<on
Differen<alPropermo<on
Piatek et al 2008
PMindifferentfields(HST2yr)indicatesrota<onintheLMCandradialexpansionintheSMC
WhatisthePMinspaceand<me?ΔPM=0.8‐1mas/yramongdifferentfieldsVMCcanreachPMaccuracyof0.05mas/yrcomparablewithHSTfrommanystarsandreferenceobjectsperresolu<onelement(TBD)
SMC LMC
ExtractfromshoppinglistVMCwillnaturallyleadtospectroscopicfollow‐upstudies
MCsaretheclosestexampleofinterac<nggalaxiesMCsarealaboratoryforstellarevolu<on
VMCsurvey(2009‐2014)
totalmetallicity‐error<0.1dex age‐error20%in0.1deg2 depth‐error0.2kpc propermo<onofdifferentpopula<ons‐error0.05mas/yr
Spectroscopicsurvey
[Fe/H]withsmallerrors Measureαandotherelementsabundances Confirm/selecttargets MeasureradialvelocityGAIA(2011‐)Metallicity,radialvelocityandpropermo<onofbrightgiants
Short‐term:low‐res/molecules;high‐res/limitedFoV/samples Long‐term:wide‐field/faintpopula<ons
Photometry&Spectra:
structurevs<me chemistryvs<meandstructure globalevolu<on/simula<onofthesystem