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S. CRISTALLO (1) O. Straniero (1) R. Gallino (2) L. Piersanti (1) (1) Osservatorio di TERAMO, INAF (2) Universita di Torino Sintesi di elementi leggeri.

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Presentation on theme: "S. CRISTALLO (1) O. Straniero (1) R. Gallino (2) L. Piersanti (1) (1) Osservatorio di TERAMO, INAF (2) Universita di Torino Sintesi di elementi leggeri."— Presentation transcript:

1 S. CRISTALLO (1) O. Straniero (1) R. Gallino (2) L. Piersanti (1) (1) Osservatorio di TERAMO, INAF (2) Universita di Torino Sintesi di elementi leggeri in stelle di ramo asintotico

2 p-process (proton-rich nuclei) s-process (AGB Stars) r-process (SuperNovae)

3 THE AGB PHASE 1: THE SCHEME

4 STARTING PARAMETERS [Fe/H]=0 but.... Z = Z α mixing length = 1.9He ini = 0.27 Calibration of the SSM (Standard Solar Model) with the new composition New determination of solar C, N and O (Allende-Prieto et al. 2002, Asplund et al. 2004): (Allende-Prieto et al. 2002, Asplund et al. 2004): Z ini Z/X=

5 How we treat the convection Schwarschild criterion: to determine convective borders Mixing length teory: to calculate the element velocities inside the convective zones At the boundaries we assume thatAt the boundaries we assume that the velocity profile drops, following an exponentially decaying law v = v bce · exp (-d/β H p ) where: V bce is the convective velocity at the inner border of the convective envelope (CE) d is the distance from the CE H p is the scale pressure height β = 0.1 REF: Freytag (1996), Herwig (1997), Chieffi (2001), Cristallo (2001,2004) WARNING: v bce =0 except during Dredge Up episodes Efficiency of the mixing: we take it proportional to the ratio between the convective time scale and the time step of the calculation (Spark & Endal 1980)

6 About 500 isotopes More than 700 reactions fully coupled with the physic evolution Reactions Reference (n,γ) (n,p) and (n,α) p and a captures beta decay Bao & Kaeppeler Koehler,Wagemans NACRE Takahashi&Yokoi THE NETWORK

7 Some examples… LEGENDA: Around 26 Al The bottlenecks

8 ACTIVATION OF THE 13 C(α,n) 16 O reaction First formation of the 13 C-pocket 2: THE MODEL THE AGB PHASE M=2M Z=Z

9 Formation of the 13 C-pocket after a Pulse with Third Dredge Up 12 C 13 C 22 Ne 14 N 23 Na H

10 Variation of the 13 C-pocket pulse by pulse X( 13 C eff )=X( 13 C)-X( 14 N)

11 Efficient in radiative conditions in the He-intershell at stellar low energies Very difficult to measure it due to the presence of a sub-treshold resonance REFERENCES: 1.Caughlan&Fowler (1988) 2.Drotleff et al. (1993) 3.Angulo et al. (1999) 4.Kubono et al. (2003) At T 8 =1: differences by a factor of 4!!!! The 13 C(α,n) 16 O reaction

12 Final surface elements distribution 13 C(α,n) 16 O from Drotleff et al. (1993) 0.1 deX (maximum) using Kubono (2003) and NACRE (1999)

13 M=2M Z= C 14 N 19 F 15 NH Production of 15 N and 19 F

14 EXCERCIZES TESTS (better EXCERCIZES...): 18 O(p,α) 15 N Rate multiplied by 2 About 50 resonances between 20 and 6746 KeV 15 N(p,α) 12 C Rate divided by 2 Experimental data at low energies from: Redder et al Zyskind et al N(n, γ ) 15 N 15 N(n, γ ) 16 N 14 C(p, γ ) 15 N 14 C(n, γ ) 15 C 14 C( α, γ ) 18 O Rate divided by 2

15 He-intershell abundances at the end of the following Thermal Pulse CASE 15 N 19 F 23 Na Standard 2.86 · · · O(p,α) 15 N x · · · N(p,α) 12 C / · · · C(α, γ ) 18 O / · · · %-20%

16 M=2M Z= C 26 Al 60 Fe 41 Ca H RADIACTIVE ISOTOPES

17 M=2M Z=Z ( 40 Ca/ 41 Ca) equilibrium

18 The 14 N(n,p) 14 C reaction Our choice (ST) : Koehler, P.E. & OBrien, H.A. (1989, Phys. Rev C 39, 1655) EXERCIZES ST x 2 ST / 2

19 Convective envelope CO-core He Low M - Low Z AGB: M=1.5 Z=5x10 -5 Y= C CNO 13 C(,n) (Straniero et al. 2005)

20 He H See also: Hollowell, Iben & Fujimoto 1990 Fujimoto, Ikeda & Iben 2000 Iwamoto et al. 2004

21 13 C 14 N 19 F 15 N H Production of 15 N and 19 F M=1.5M Z=5x10 -5

22 Envelope composition 12 C/ 13 C C/O 14 N/ 15 N M=1.5M Z=5x10 -5 Sergio Cristallo: Il C12/C13 scende perche e la concentrazione di equilibrio del bruciamento di H convettivo Il C/O al secondo pulso scende perche porta su O, mentre C e gia enhanced N14/N15 scende perche il pulso successivo non e riuscito a bruciare il amre di N15 che si era formato. Mentre lN14 e tutto bruciato. Sergio Cristallo: Il C12/C13 scende perche e la concentrazione di equilibrio del bruciamento di H convettivo Il C/O al secondo pulso scende perche porta su O, mentre C e gia enhanced N14/N15 scende perche il pulso successivo non e riuscito a bruciare il amre di N15 che si era formato. Mentre lN14 e tutto bruciato.

23 Production of heavy elements (s-process) 13 C 14 N 139 La 89 Y H 208 Pb M=1.5M Z=5x10 -5

24 M=1.5M Z=5x10 -5

25 THE NATIONAL RESEARCH COUNCIL COMMITTEE ON PHYSICS 1. What is dark matter? 2. What is dark energy? 3. How were the heavy elements from iron to uranium made? 4. Do neutrinos have mass? 5. Where do ultra-energy particles come from? 6. Is a new theory of light and matter needed to explain what happens at very high energies and temperatures? 7. Are there new states of matter at ultrahigh temperatures and densities? 8. Are protons unstable? 9. What is gravity? 10. Are there additional dimensions? 11. How did the Universe begin? (Febbraio 2002) What about elements from idrogen to iron???


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