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18-19 Settembre 2006 Dottorato in Astronomia Università di Bologna
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The Virial Theorem
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log log P 5/3 4/3 M1M1 M2M2 Non-degenerate Non-relativistic relativistic Collapse or ignition Stellar core evolution Degenerate Fermi gas
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Stellar evolution M<0.8 M 0.8<M/M <8 8<M/M <11 11<M/M <100 M>100 M Gyr Myr 0.5<M f /M <1.1 CO WD . Myr M f =1.2-1.3 M ONeMg WD <10 Myr M f =1.2-2.5 M Fe (Y e. 0.45) collapse NS or BH few Myr O (pair jnstability) (Y e =0.5) may or may not explode Thermonuclear SNe Progenitors Core Collapse SNe Progenitors
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Summary: Age of simple (stellar clusters) and complex (disk, bulge, halo) stellar populations. Properties of nowadays extinct stellar populations. Nature of barionic dark matter Physics of high density matter Amount of C/O in the He-exhausted core: hints for nuclear physics and theory of turbulent convection, as well as constraints for massive stars evolution and any type of SNe
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47 tuc (Zoccali et al 2001)
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M4 (Bedin et al. 2001)
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NGC 6397 (King et al. 1998)
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Data obtained with the WFPC2 on board the HST (Hansen et al. 2002, Richer et al. 2002). The target is a region located 5’ E of the center of M4 and has been imaged through the: F606W (98 orbits x 1300 sec) F814W (148 orbits x 1300 sec) M4: the deepest WD cooling sequence 12.7 " 0.7 Gyr.
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Cooling sequence
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Age from luminosity functions Crystallization phase Debye cooling Convective coupling WD cooling Different colors > different WD masses
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WD Age from the CM-diagram: Collision Induced Abortion (CIA) and the blue hock Isochrones for DA WD
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Simulated WD sequence in NGC6397 with ACS
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NGC 6397
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Good match between theory and observation Good description of the high density matter behavior Bad: only a lower limit for the age can be set: 9 Gyr The observed WD Luminosity function Good: smaller dependence on the distance
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WDs are relicts of an extinct population: progenitors mass function: Synthetic NGC 6397 13 Gyr - Salpeter mass function
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98% C-O core (0.5-1.1 M À ) 2% He mantel (<10 -2 M À ) 0.01% H envelope (<10 -4 M À ) no conduction e - highly degenerateisothermal envelope core energy reservoir C-O ions main energy reservoir e - non-degenerate thermal insulator DA White Dwarf
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Thermal conductivity by degenerate electrons From Prada Moroni & Straniero 2002 C/O Core He-rich Mantel
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WD progenitors Case B no-AGB Case B1 Post-AGB with final thermal pulse Case B2 classical Post- AGB Case C Post RGB
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4 He 16 O 12 C 5 M Z=0.02 Y=0.28 He-burning: the competition between 3 -> 12 C and 12 C+ -> 16 O+
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E x (keV) JJ 10957 10367 9847 9580 8872 7117 6917 6130 6049 0 0-0- 4+4+ 2+2+ 1-1- 2-2- 1-1- 2+2+ 3-3- 0+0+ 0+0+ 12 C+ 4 He 2418 2685 3195 E CM (keV) Gamow peack energies -45 -245 16 O 16 O level scheme Q = 7.162 MeV LowAdop.high Kunz et al 2001 5.257.5810.2 Buchman n 1996 3.047.0413.04 NACRE 5.449.1112.8 CF88 4.74 CF85 11.3 N a (10 -15 cm 3 mol -1 s -1 ) for T 9 =0.2
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White Dwarf interior: C and O profiles 12 C( ) 16 O High rate Low rate
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cooling is affected by the internal chemical stratification high rate low rate
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4 models for convection same nuclear reaction rates different convective scheme
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WD internal composition is affected by core He burning convection MDMD 16 O
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At the onset of the core collapse e - +p n+ e (10 MeV) 56 Fe+ 13 +4n (124 MeV)
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SNe Ia: Theoretical Light Curves
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