S. CRISTALLO (1)

O. Straniero (1)

R. Gallino (2)

L. Piersanti (1) (1) Osservatorio di TERAMO, INAF

(2) Universita’ di Torino

Sintesi di elementi leggeriin stelle di ramo asintotico

p-process (proton-rich nuclei)

s-process (AGB Stars)r-process (SuperNovae)

THE AGB PHASETHE AGB PHASE 1: THE SCHEME

STARTING PARAMETERSSTARTING PARAMETERS

[Fe/H]=0 but....Z = Z

αmixing length = 1.9Heini = 0.27

• Calibration of the SSM (Standard Solar Model) withthe 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):

Zini 0.015

Z/Z/X=0.0176X=0.0176

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 that At the boundaries we assume that the velocity profile drops, following the velocity profile drops, following an exponentially decaying lawan exponentially decaying law

v = vbce · exp (-d/β Hp) where:

• Vbce is the convective velocity at the inner border of the convective envelope (CE)

• d is the distance from the CE

• Hp is the scale pressure height

• β = 0.1

REF: REF: FreytagFreytag (1996), (1996), HerwigHerwig (1997), (1997),ChieffiChieffi (2001), (2001), CristalloCristallo (2001,2004) (2001,2004)

WARNING: vbce=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)

About 500 isotopes

More than More than 700700 reactions reactionsfully coupled withfully coupled with

the physic evolutionthe physic evolution

Reactions Reference(n,γ)

(n,p) and (n,α)p and a captures

beta decay

Bao & KaeppelerKoehler,Wagemans

NACRETakahashi&Yokoi

THE NETWORK

Ba134 Ba135 Ba136 Ba137 Ba138Cs133 Cs134 Cs135 Cs136 Cs137

Xe128 Xe129 Xe130 Xe131 Xe132 Xe133 Xe134 Xe135 Xe136I127 I128 I129 I130 I131 I132 I133

Te127 Te128 Te130

P31Si28 Si29 Si30 Si31

Al26 Al27Mg24 Mg25 Mg26

Na22 Na23 Na24Ne21 Ne22

(a,g) (p,g) (n,g) Beta Decay(a,n) (p,a) (n,p) (n,g)+alfa decay(a,p) 3alfa (n,a)

Zr90 Zr91Y89 Y90 Y91

Sr86 Sr87 Sr88 Sr89 Sr90 Sr91Rb85 Rb86 Rb87 Rb88

Kr83 Kr84 Kr85 Kr86 Kr87 Kr88Br83 Br84

Some examples…LEGENDA: Around 26Al

The bottlenecks

Po210Bi209 Bi210

Pb204 Pb205 Pb206 Pb207 Pb208 Pb209 Pb210Tl203 Tl204 Tl205Hg203 Hg204

ALFA Decay

ACTIVATIONOF THE

13C(α,n)16O reaction

First formationof the 13C-pocket

2: THE MODELTHE AGB PHASETHE AGB PHASEM=2M

Z=Z

Formation of

the 13C-pocket after a

Pulse with

Third Dredge Up

12C13C

22Ne

14N

23Na

H

Variation of the 13C-pocket pulse by pulse

X(13Ceff)=X(13C)-X(14N)

•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:REFERENCES:

1. Caughlan&Fowler (1988)2. Drotleff et al. (1993)3. Angulo et al. (1999)4. Kubono et al. (2003)

At T8=1: differencesby a factor of 4!!!!

The 13C(α,n)16O reaction

Final surface elements distribution

,

,loglog

Fe

El

Fe

El

N

N

N

N

Fe

El

13C(α,n)16O from Drotleff et al. (1993)

0.1 deX (maximum) using Kubono (2003) and NACRE (1999)

M=2M

Z=10-4

13C14N

19F

15N

H

Production of Production of 1515N and N and 1919FF

TESTS (better EXCERCIZESEXCERCIZES...):

18O(p,α)15N Ratemultiplied by 2

About 50 resonances between 20 and 6746 KeV

15N(p,α)12C Ratedivided by 2

Experimental data at low energies from:Redder et al. 1982Zyskind et al. 1979

14N(n,γ)15N 15N(n,γ)16N

14C(p,γ)15N

14C(n,γ)15C

14C(α,γ)18O Ratedivided by 2

He-intershell abundances at the end of the following Thermal Pulse

CASE 15N 19F 23Na

Standard 2.86·10-9 1.88·10-5 8.59·10-5

18O(p,α)15N x 2 5.84·10-9 2.18·10-5 8.67·10-5

15N(p,α)12C / 2 3.75·10-9 2.27·10-5 8.61·10-5

14C(α,γ)18O / 2 2.77·10-9 1.58·10-5 8.64·10-5

+20%-20%

M=2M

Z=10-4

13C26Al

60Fe

41Ca

H

RADIACTIVE ISOTOPESRADIACTIVE ISOTOPES

M=2M

Z=Z

(40Ca/ 41Ca)equilibrium

The 14N(n,p)14C reaction

Our choice (ST): Koehler, P.E. & O’Brien, H.A.

(1989, Phys. Rev C 39, 1655)

EXERCIZES

ST x 2 ST / 2

Convective envelope

CO-core

He

Low M - Low Z AGB: M=1.5 Z=5x10-5 Y=0.24

312C

CNO

13C(,n)

(Straniero et al. 2005)

He

H

1 3 4

2

See also:

Hollowell,

Iben &

Fujimoto

1990

Fujimoto,

Ikeda &

Iben 2000

Iwamoto et al.

2004

13C14N

19F

15N

H

Production of Production of 1515N and N and 1919FF

M=1.5M

Z=5x10-5

Envelope compositionEnvelope composition12C/13C

C/O

14N/15N

M=1.5M Z=5x10-5

Production of heavy elements (Production of heavy elements (ss-process)-process)

13C14N

139La

89Y

H

208Pb

M=1.5M

Z=5x10-5

M=1.5M

Z=5x10-5

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 elementsfrom idrogen to iron???