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Stellar populations in

- Ringberg Castle, July 15, 200 8 -. First results from LBC imaging:. Stellar populations in. Galactic Globular Clusters. Giacomo Beccari Astronomy Dept. - Bologna University (ITALY).

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Stellar populations in

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  1. - Ringberg Castle, July 15, 2008 - First results from LBC imaging: Stellar populations in Galactic Globular Clusters Giacomo Beccari Astronomy Dept. - Bologna University (ITALY) In collaboration with L.Pulone, F.R.Ferraro, B.Lanzoni, M.Bellazzini, F.Fusi Pecci, R.T. Rood, and the LBC-Team at Astronomical Observatory of Rome

  2. Summary • The scientific target: • The stellar populations in Galactic Globular Clusters • Observational technique: • The multi-telescope approach • Space Telescope HST High-UV plus/versus LBC@LBT • Data reduction: • PSF photometry in crowded fields • Accurate astrometry • Scientific results and future: • The radial distribution of the Blue Straggler Stars • The binary fraction • Radial density profile • White Dwarf Cooling Sequence? (…may be)

  3. ASTRO – TEMPLATES LABORATORY for theoretical models of stellar evolution ASTRO – ARCHEOLOGY TRACERS of the structure & history of the Galaxy ASTRO – DYNAMICS LABORATORY dynamicsSE GALACTIC GLOBULAR CLUSTERS Gravitationally-bound system made of million of stars: • Coeval (old) • Chemically homogeneous

  4. Stellar populations in GCs AGB HB RGB SGB MS by-products of binary systems “Canonical” evolutionary sequences Anomalous sequences populated with by-products of binary evolution BSS • BSS formation channels: • primordial binaries (PB-BSS) • In low density environment • vs • direct collisions (COL-BSS) • In high density environment UVE

  5. Observational Strategies: Multi-telescope High resolution Wide field ACS@HST LBC@LBT FoV~3.4’x3.4’ FoV~24’x23’ What do we need? • PSF photometry in crowded fields • ROMAFOT, DaoPhot, DoPHOT • Accurate Astrometry

  6. PSF photometry with LBC • Variation of the FWHM of the PSF on the chips: • Third degree needed for properly sample it;

  7. Astrometry of LBC data - CataXcorr (byP.Montegriffo@INAF-OABO) residuals<0.3”

  8. The Targets rho_0 [Lο/pc3] [Fe/H] NGC 5024 (M53) -1.99 3.04 -2.22 0.85 NGC 5466 -2.28 4.29 NGC 6341 (M92)

  9. 5’ x 5’ NGC 5024 (M53) with LBC-Blue DATA-SET - Science Demonstration Time (SDT) Jan - May 2007 LBC-Blue - B - 10 sec

  10. NGC 5024 (M53) – LBC-Blue Bright sample Canonical Evolutionary Sequences AGB r <~ 14’ HB Exotic Objects RGB BSS SGB TO MS Pre-reduction - pipeline for LBC from LBC Team Data Reduction - DAOPHOT (Stetson 1987) Photometric Calibration - CMD from Rey et al. 1998, ApJ, 116, 1775

  11. LBC@LBT:Wide field coverage over the cluster extension ACS@HST:High resolution sampling of the core region Multi-telescope approach

  12. r>120” r<120” Results (1): The BSS in NGC5024 (M53) DEFINITION OF THE SAMPLES Definition of the BSS selection box and reference population - HB r>120” r<120”

  13. BSS radial distribution Division of FoV in concentric annuli Ratio of N(BSS)/N(HB) in each ring BIMODAL RADIAL DISTRIBUTION UPTURN IN EXTERNAL REGIONS (r>~150 arcsec) MASS SEGREGATION Powerful tool for comparative study of BSS in different globular cluster (Bailyn et al. 1995; Ferraro et al. 2003, 2004; Piotto et al. 2004; Beccari et al. 2006; Lanzoni et al. 2007)

  14. BSS radial distribution Bimodal in 7 cases Dynamical simulations suggest that if the BSS radial distribution is BIMODAL, PB-BSS should exist in the outskirts Ferraro et al. (2004); Beccari et al. (2006); Lanzoni et al. (2007a) Lanzoni et al. (2007b); Beccari et al. (2008)

  15. Results (2): radial density profile • Fit with standard King Model • allows an estimate of cluster • dynamical parameters • Tidally stripped stars? Beccari et al. 2008

  16. LBC@LBT B~25.5 U~24.5 NGC 5024 (M53) – LBC-Blue Deep sample CHIP #3 - 250”<r<650” Fraction of binary systems in the externals

  17. Deep imaging - NGC 6341 (M92) Core Region Tidal radius • The binary fraction • The White Dwarf Cooling Sequence

  18. NGC 5466 INAF press release

  19. NGC 5466 Age from Vertical Method LBC@LBT r<120” ACS@HST r<120” ZAHB 1.1 Mο 1.0 Mο 0.9 Mο TO Teramo evolutionary models Teramo evolutionary models

  20. The end…thank you!!!

  21. Calamida et al. (2008)

  22. Observational Strategies: Multi-band The "classical" plane The UV plane HB HB RGB BSS BSS RGB MS MS Optical Plane UV Plane

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