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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@rm.iasf.cnr.it. 25 M O. 5 M O. 1 M O. REMEMBER that:

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slide1

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@rm.iasf.cnr.it

slide2

25 MO

5 MO

1 MO

slide3

REMEMBER that:

The interplay between the evolution of a star and the nuclear processes occurs through the RATES and NOT the cross sections:

Rlk => Xl x Xk x screening x <sv>lk

slide4

25 MO

Dt(H-burn)= - 0.3%

M(He) => 8.3 to 8.6 MO

CNO cycle

<sv>3a x 10 is NOT appreciable

14N(p,g)15O

x 10

5 MO

CNO cycle

M(He) => 0.91 to 0.97 MO

Dt(H-burn)= - 4%

1 MO

PP chain

p(p,e+n)d

Dt(H-burn)= - 3%

slide5

HB

RGB

TO

MS

slide6

Z=10-4

Y=0.23

Solid => reference

Dashed => (14N(p,g)15O) / 2

10 Gyr

13 Gyr

slide7

M=0.8 MO

Y=0.23

Z=10-4

Red – reference

Blue – 14N(p,g)15O / 2

  • MHe = 1%
  • Mbol(tip) = 0.055 Mag

-0.04 Mag => - 0.6 Gyr

slide8

AGB phase

0.7 < M / MO < 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

slide9

Convective envelope

H shell

M(MO)

He shell

t(yr)

slide10

Convective envelope

H shell

M(MO)

He conv. shell

He shell

t(yr)

slide11

-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

slide13

M=3 MO Z=0.02 Y=0.284

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

slide14

Log10(PF)

Element

slide15

Log10(PF)

Stable Isotopes

slide16

M=3 MO - Z=0.02

Reference

3a / 2

3a x 2

14Npg / 2

slide17

SURFACE CARBON ABUNDANCE

Reference

3a / 2

3a x 2

14Npg / 2

slide19

Roadmap...

1) WR stars: evolution & explosive nucleosynthesis

120

35

2) Intermediate Mass Stars: elemental yields