Characterisation of the FSR star cluster sample Dirk Froebrich A.Buckner A.Scholz, H.Meusinger, S.Schmeja, et al. Heidelberg, 30/07/2013 Layout of the talk 0) Introduction 1) The FSR Cluster Sample 2) Photometric Decontamination 3) Old Clusters 4) Distance determination 5) Results/Conclusions Heidelberg, 30/07/2013 Why ? bother FSR 0190 Heidelberg, 30/07/2013 Why ? bother Most (~90%) stars are formed in clusters. Lada & Lada (2003) Heidelberg, 30/07/2013 Why ? bother Most (~2/3) stars are formed in clusters. Megeath et al. (2008) Heidelberg, 30/07/2013 Why ? bother i.e. star clusters are the building blocks of galaxies Heidelberg, 30/07/2013 Why ? bother (most) star clusters die young (infant mortality) i.e. they dissolve into the field star population Heidelberg, 30/07/2013 Why ? bother star clusters are samples of stars with (almost) identical distance, reddening, age and metallicity Heidelberg, 30/07/2013 Why ? bother they are hence ideal laboratories to study stellar evolution, star formation, galactic structure, formation and evolution of the Galaxy Heidelberg, 30/07/2013 The FSR Cluster Sample JHK star density maps 14400square degrees each 3.5‘ resolution 20“pixels 0.5GigaPixel images Froebrich et al. (2007) Heidelberg, 30/07/2013 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) Heidelberg, 30/07/2013 The FSR Cluster Sample SIMBAD 86 GlC, 681 OpC, 1021 new cluster candidates (1788 objects in total) use 0.5° 0.5° x 0.5° 0.5° field of 2MASS to fit central position (model cluster as 2D density distribution) determine radius via: Heidelberg, 30/07/2013 Fore/Background decontamination adaptation of the (Bonatto & Bica 2007) decontamination procedure Heidelberg, 30/07/2013 Fore/Background decontamination adaptation of the (Bonatto & Bica 2007) decontamination procedure calculate CCM distance between all stars i and j in the cluster area: i,j find Nth smallest rCCM distance find number of stars NCCM within this distance in control field determine membership probability as: N Froebrich et al. (2010) Heidelberg, 30/07/2013 Fore/Background decontamination FSR 0412 – Pfleiderer3 Heidelberg, 30/07/2013 Selection/Analysis of Old Clusters Look at all 1788 decontaminated CCDs and CMDs (blind test!) select all cluster candidates with RG and/or MS stars 269 old clusters 63 GlC, 174 known OpC 32 so far unclassified OpC obtain properties from WEBDA, Harris 1996, other literature fit Isochrones with literature data as a start, + finetuning Heidelberg, 30/07/2013 Results for Old Clusters FSR 0412 – Pfleiderer3: Log(age/yr)=9.1; D=6.1kpc; AK=0.46mag Heidelberg, 30/07/2013 Results for Old Clusters Parameter uncertainties: (from comparison with literature values) Positions --- about 2‘ Radii --- r[pc] = 0.15 .. 0.30 * d[kpc] Distances --- about 30% log(Age) --- 10% Reddening --- 30% Heidelberg, 30/07/2013 Results for Old Clusters Age Distribution: this work literature Heidelberg, 30/07/2013 Results for Old Clusters Distribution in Galactic Plane: GlC Old OpC OpC Heidelberg, 30/07/2013 Results for Old Clusters Distribution in Galactic Plane: GlC Old OpC OpC Heidelberg, 30/07/2013 Conclusions on Old Clusters Distribution in Galactic Plane: in b: peak at -0.6° ± 7.0° in Z: peak at -33pc ± 375pc (age >=1Gyr) ± 115pc (age < 1Gyr) 80% of old OpC have dGC > 8kpc only 3% of old OpC have dGC < 5kpc unexplained paucity of clusters at 120° < l < 180° (not a high AV region) Average reddening law: 0.70mag AV per kpc distance (inside one scale height) Froebrich et al. (2010) Heidelberg, 30/07/2013 What other people have done... 309 FSR candidate clusters are in the online version of the Dias et al. star cluster catalogue 79 citations to the FSR catalogue paper Bica, Bonatto, Borissova, Camargo, Hanson, Messineo, Ortolani, Solin, Straizys,...., et al. Heidelberg, 30/07/2013 Analysis of full sample FSR 0233 – LK10 Buckner & Froebrich (2013) Heidelberg, 30/07/2013 Analysis of full sample FSR 0233 – LK10 Buckner & Froebrich (2013) Heidelberg, 30/07/2013 Analysis of full sample FSR 0233 – LK10 Buckner & Froebrich (2013) Heidelberg, 30/07/2013 Analysis of full sample 2MASS data for all FSR clusters within 0.5° selected if: >30 stars with Qflag=AAA within core radius >30 stars in control field (0.5° > radius > 5 core radii) core radius <0.05° Distances determined from foreground star density and Besancon Galaxy Model (BGM) Buckner & Froebrich (2013) Heidelberg, 30/07/2013 Analysis of full sample clusterss Cluster calibration samples (CCS) from WEBDA and old FSR cluster Unique match within 7.5arcminutes 115 old FSR clusters 241 WEBDA clusters Buckner & Froebrich (2013) Heidelberg, 30/07/2013 Analysis of full sample Correction of measured foreground star density to account for crowding (in field and cluster) and large scale extinction Measure the logarithmic distance ratio: Buckner & Froebrich (2013) Heidelberg, 30/07/2013 Analysis of full sample Buckner & Froebrich (2013) Heidelberg, 30/07/2013 Analysis of full sample Parameter study to minimise scatter of R. Buckner & Froebrich (2013) Heidelberg, 30/07/2013 Analysis of full sample Other models? e.g. TRILEGAL Buckner & Froebrich (2013) Heidelberg, 30/07/2013 Results of full sample Extinction determination d<5kpc d>5kpc Heidelberg, 30/07/2013 Results of full sample Known Clusters Cluster Candidates Buckner & Froebrich (2013) Heidelberg, 30/07/2013 Results of full sample 771 objects with distances 377 known clusters (55%) 394 cluster candidates (39%) 775 objects with extinction values, YSO fraction 378 known clusters (56%) 397 cluster candidates (39%) 15 clusters per kpc2 at 22-4kpc Scale height 190pc for young clusters (YSO fraction >1%) 300pc for old clusters (YSO fraction <1%) Buckner & Froebrich (2013) Heidelberg, 30/07/2013 Results of full sample Known Clusters Cluster Candidates Heidelberg, 30/07/2013 Results of full sample Known Clusters Cluster Candidates Heidelberg, 30/07/2013 Results of full sample Heidelberg, 30/07/2013 Results of full sample <H-4.5> <H-K> Heidelberg, 30/07/2013 Results of isochrone fitting isochrone fits for 216 known and 82 new clusters Heidelberg, 30/07/2013 Future Work Quantify the selection effects in the sample as a function of age, position Study evolutionary trends in the selection bias corrected samples Analyse clusters in UKIDSS and VISTA survey fields with deeper, higher resolution data Select the most interesting objects massive cluster candidates old clusters near the GC Heidelberg, 30/07/2013 END Heidelberg, 30/07/2013