The role of (some) nuclear reaction rates

1
The role of (some) nuclear reaction rates in the
evolution of the stars of low, intermediate and
high mass
Alessandro Chieffi (Istituto di Astrofisica
Spaziale e Fisica Cosmica INAF) Email
achieffi_at_rm.iasf.cnr.it
2
25 MO
5 MO
1 MO
3
REMEMBER that The interplay between the
evolution of a star and the nuclear processes
occurs through the RATES and NOT the cross
sections
Rlk gt Xl x Xk x screening x ltsvgtlk
4
25 MO
Dt(H-burn) - 0.3
M(He) gt 8.3 to 8.6 MO
CNO cycle
ltsvgt3a x 10 is NOT appreciable
14N(p,g)15O
x 10
5 MO
CNO cycle
M(He) gt 0.91 to 0.97 MO
Dt(H-burn) - 4
1 MO
PP chain
p(p,en)d
Dt(H-burn) - 3
5
HB
RGB
TO
MS
6
Z10-4 Y0.23
Solid gt reference
Dashed gt (14N(p,g)15O) / 2
10 Gyr
13 Gyr
7
M0.8 MO Y0.23 Z10-4
Red reference Blue 14N(p,g)15O / 2

• MHe 1
• Mbol(tip) 0.055 Mag

-0.04 Mag gt - 0.6 Gyr
8
AGB phase
0.7 lt M / MO lt 7
He burning shell
R(Hshell) 10-5 Rstar
CO core
He (C) intershell
Neutron production s process nucleosynthesis
H burning shell
H-rich mantle
9
Convective envelope
H shell
M(MO)
He shell
t(yr)
10
Convective envelope
H shell
M(MO)
He conv. shell
He shell
t(yr)
11
-1 8.5 7.5
Base conv. env.
H burn. shell
He burn. shell
Log(Surf. C abund.)
Log(Tmax He shell)
Log(T base conv. Env.)
-3 8.1 6.5
12
He luminosity
13
M3 MO Z0.02 Y0.284
Network H to Si (full)
Neutron captures on Fe Kr84 Rb Sr Y
Zr92 Xe132 Cs Ba La Ce Pr Nd144 Hg202
Tl Pb Bi209
92 nuclei
14
Log10(PF)
Element
15
Log10(PF)
Stable Isotopes
16
M3 MO - Z0.02
Reference
3a / 2
3a x 2
14Npg / 2
17
SURFACE CARBON ABUNDANCE
Reference
3a / 2
3a x 2
14Npg / 2
18
The mother of all rates 12C(a,g)16O
19
Roadmap...
1) WR stars evolution explosive nucleosynthesis
120
35
2) Intermediate Mass Stars elemental yields
20
(No Transcript)