1. 18-19 Settembre 2006 Dottorato in Astronomia Università di Bologna

2. The Virial Theorem

3. log  log P  5/3  4/3 M1M1 M2M2 Non-degenerate Non-relativistic relativistic Collapse or ignition Stellar core evolution Degenerate Fermi gas

4. 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

5. 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

6. 47 tuc (Zoccali et al 2001)

7. M4 (Bedin et al. 2001)

8. NGC 6397 (King et al. 1998)

9. 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.

10. Cooling sequence

11. Age from luminosity functions Crystallization phase Debye cooling Convective coupling WD cooling Different colors > different WD masses

12. WD Age from the CM-diagram: Collision Induced Abortion (CIA) and the blue hock Isochrones for DA WD

13. Simulated WD sequence in NGC6397 with ACS

14. NGC 6397

15. 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

16. WDs are relicts of an extinct population: progenitors mass function: Synthetic NGC 6397 13 Gyr - Salpeter mass function

17. 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

18. Thermal conductivity by degenerate electrons From Prada Moroni & Straniero 2002 C/O Core He-rich Mantel

19. WD progenitors Case B no-AGB Case B1 Post-AGB with final thermal pulse Case B2 classical Post- AGB Case C Post RGB

20. 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+ 

21. E x (keV) JJ 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

22. White Dwarf interior: C and O profiles 12 C(  ) 16 O High rate Low rate

23. cooling is affected by the internal chemical stratification high rate low rate

24. 4 models for convection same nuclear reaction rates different convective scheme

25. WD internal composition is affected by core He burning convection MDMD 16 O

26. At the onset of the core collapse e - +p  n+ e (10 MeV) 56 Fe+   13  +4n (124 MeV)

27. SNe Ia: Theoretical Light Curves