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Dirk Froebrich Do we know all the Milky Way Globular Clusters? Dirk Froebrich JENAM Conference, 15.09.2008 People 1) Candidates from the FSR Cluster Sample A. Scholz H. Meusinger C.J. Davis C.L. Raftery 2) Candidates from the GPS and Mercer list A. Longmore R. Kurtev T. Macarone P.W. Lucas V.D. Ivanov D. Minniti J. Borissova R. de Grijs JENAM Conference, 15.09.2008 Known Galactic Globular Clusters 158 kown (pre FSR catalogue or 2007) Harris (1996, 2003) lists 150, + Glimpse-C01 (Kobulnicky et al. 2005), GC Whiting1 (Carraro et al. 2005), SDSS J1049+5103 SDSS J1257+3419 (Willman et al. 2005), AL3 (Ortolani et al. 2006), GC SEGUE1 (Belokurov et al. 2007), Koposov1 Koposov2 (Koposov et al. 2007) JENAM Conference, 15.09.2008 Whybother? apparent difference in numbers of MW Globular Clusters compared to e.g. the Andromeda galaxy true or selection effect? study the formation and evolution of the Galaxy some GlCls are from captured dwarf galaxies probe the structure of the Galaxy JENAM Conference, 15.09.2008 The FSR Cluster Sample JENAM Conference, 15.09.2008 The FSR Cluster Sample Zone of Avoidance High extinction and star density Æ low density contrast between cluster and background distant clusters are obscured by dust 10±3 GlCl are ‘missing’ within 3kpc from the Galactic Center and near the Galactic Plane (Z<0.5kpc) (Ivanov et al. 2005) Froebrich et al. (2007) JENAM Conference, 15.09.2008 The FSR Cluster Sample JHK star density maps 14400square degrees each 3.5‘ resolution 20“pixels Æ 0.5GigaPixel images 120hours computing time on 16node double processor Beowulf-type cluster Froebrich et al. (2007) JENAM Conference, 15.09.2008 The FSR Cluster Sample Search for local enhancements in JHK star density maps use SExtractor (Bertin & Arnouts 1996) 4σ above local (10°x5°) noise and >11square arcmin + manual search cloud edges and spikes of bright stars rejected fainter objects with cluster like appearance added every cluster must be detected in H and (J or K) 2iterations between two people for validation! Froebrich et al. (2007) JENAM Conference, 15.09.2008 The FSR Cluster Sample 1788 cluster candidates detected 782 automatically, 1006 manually ratio of auto/manu constant along Galactic Plane SIMBAD cross referencing: 86 known GlCl (out of 93 with d<17kpc in this area) 681 known OpCl 1021 new cluster candidates ~500 real new clusters JENAM Conference, 15.09.2008 Classification King (1962) radial density profile Automatic fit at local completeness limit, excluding regions with source confusion (dense cluster centers) Manual verification of validity via majority decision Froebrich et al. (2007) JENAM Conference, 15.09.2008 Classification Op/Gl Op/Gl Op Gl Pplot = N / (N + N ) i for each plot and cluster /(681/86) Froebrich et al. (2007) JENAM Conference, 15.09.2008 Classification new GlCl (85%) OpCl (95%) Froebrich et al. (2007) JENAM Conference, 15.09.2008 Classification of Star Clusters C1716 Glimpse C01 Log(RN)=-0.060 Log(RN)=-0.851 JENAM Conference, 15.09.2008 Classification of Star Clusters C1735 Glimpse C01 Log(RN)=+0.238 Log(RN)=-0.851 JENAM Conference, 15.09.2008 The FSR Cluster Sample http://astro.kent.ac.uk/~df/clusters/index.html Froebrich et al. (2007) JENAM Conference, 15.09.2008 The Mercer Cluster Sample 92 new clusters identified in GLIMPSE data Automatic detection based on Bayesian information criterion 59 detected only 6 of these detected in 2MASS automatically 24 show clustering visually 33 objects found by visual inspection of images Mercer et al. (2005) JENAM Conference, 15.09.2008 FSR 1735 Froebrich et al. (2007b/2008b) JENAM Conference, 15.09.2008 FSR 1735 ESO NTT JENAM Conference, 15.09.2008 Fore/Background decontamination Stars in cells in J, (J-H) and (J-K) space in cluster and control field are counted and stars are randomly removed according to statistics (Bonatto & Bica 2007). Cells vary in size according to stellar density. Typically they are ΔJ=0.5mag, Δ(J-H)=0.2mag and Δ(J-K)=0.2mag. JENAM Conference, 15.09.2008 Isochrone Fitting Froebrich et al. (2008b) Age>8Gyrs Ak=0.7mag d=7.0kpc [M/H]=-0.7 JENAM Conference, 15.09.2008 FSR 1716 Froebrich et al. (2008b) JENAM Conference, 15.09.2008 FSR 1716 ESO NTT JENAM Conference, 15.09.2008 Isochrone Fitting Froebrich et al. (2008b) Age>2Gyrs Ak=0.57mag d=7kpc [M/H]=-0.7±0.4 JENAM Conference, 15.09.2008 FSR 0584 Classified as probable Globular Cluster by Bica et al. (2007) based on 2MASS and proper motions JENAM Conference, 15.09.2008 FSR0584 FSR0584 Bica et al. 2007, A&A, 472, 483 Log(RN)=+0.572 Based on JHK data and proper motions, its most probably a GlCl. Projected onto W3 cloud. The closest known GlCl! d=1.4kpc AV=9.2+-0.6mag Rcore=0.3+-0.1pc Rtid=4.5+-0.5pc JENAM Conference, 15.09.2008 FSR 1767 Classified as Globular Cluster by Bonatto et al. (2007) based on 2MASS and proper motions but Froebrich et al. (2008b) JENAM Conference, 15.09.2008 FSR 1767 ESO NTT JENAM Conference, 15.09.2008 Fore/Background decontamination JENAM Conference, 15.09.2008 Isochrone Fitting Bonatto et al. (2007) Age=10Gyrs Ak=0.62mag d=1.5kpc [M/H]=-1.3 JENAM Conference, 15.09.2008 Isochrone Fitting Froebrich et al. (2008b) Age=1.25Gyrs Ak=0.4mag d=8.5kpc [M/H]=+0.0 JENAM Conference, 15.09.2008 Mercer 3 Kurtev et al. (2008) JENAM Conference, 15.09.2008 Mercer 3 ESO NTT Kurtev et al. (2008) JENAM Conference, 15.09.2008 Mercer 3 Kurtev et al. (2008), A&A, accepted or Strader & Kobulnicky (2008) subm. on astro-ph two days later... Kurtev et al. (2008) Age=??? Ak=2.7mag d=4.6kpc [Fe/H]=-0.33 JENAM Conference, 15.09.2008 Mercer 5 from Mercer et al. (2005), but independently found in UKIDSS quality control Longmore et al. (2009) in prep. JENAM Conference, 15.09.2008 Mercer 5 ESO NTT +UKIDSS JENAM Conference, 15.09.2008 Mercer5 Longmore et al. (2009) [Fe/H]=-0.94±0.16 JENAM Conference, 15.09.2008 Mercer5 Longmore et al. (2009) Age=??? Ak=1.1±0.1mag d=5-6kpc [Fe/H]=-0.94 JENAM Conference, 15.09.2008 Known Galactic Globular Clusters 161 + 2? kown 150 in Harris (1996, 2003) + Glimpse-C01 (Kobulnicky et al. 2005), GC Whiting1 (Carraro et al. 2005), SDSS J1049+5103/J1257+3419 (Willman et al. 2005), AL3 (Ortolani et al. 2006), GC SEGUE1 (Belokurov et al. 2007), Koposov1/2 (Koposov et al. 2007), FSR1735 (Froebrich et al. 2007b/2008b), FSR1767 (Bonatto et al. 2007), FSR0584? (Bica et al. 2007), FSR0190? (Froebrich et al. 2008c), FSR1716 (Froebrich et al. 2008b), Mercer3 (Kurtev et al. 2008), Mercer5 (Longmore et al. 2009) JENAM Conference, 15.09.2008 Properties of new GlCls some part of the ‘missing‘ population within ~3kpc from the Galactic Centre (e.g. FSR1735, Mercer3, Mercer5) JENAM Conference, 15.09.2008 Properties of new GlCls some part of the ‘missing‘ population within ~3kpc from the Galactic Centre (e.g. FSR1735, Mercer3, Mercer5) metallicities within [M/H] = -0.3 ... -1.0 at lower end of luminosity distribution Æ Palomar GlCls JENAM Conference, 15.09.2008 Do we know all the Milky Way Globular Clusters? Probably not, but: Further objects of the known cluster candidates from the FSR, Mercer and future GPS list might be classified as GlCl. There are no more obvious, overlooked objects in 2MASS and Glimpse. The lower end of the luminosity function is still incomplete. JENAM Conference, 15.09.2008 Conclusions We have identified 1021 new star cluster candidates with |b|<20° in star density maps (40-50% contamination rate). Follow up observations/analyses have so far revealt 3 new galactic GlCl candidates from the FSR list (plus a number of old OpCl). At least deep NIR imaging is required to verify their nature. 2MASS alone is insufficient in some cases (e.g. FSR1767)! The Mercer list of clusters also revealt 2 GlCls so far. More, probably Palomar Type GlCls, are likely to be found amongst the FSR, Mercer, and GPS lists. JENAM Conference, 15.09.2008.
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