The stellar yieldsAlessandro Chieffi

Istituto Nazionale di AstroFisica (Istituto di Astrofisica e Planetologia Spaziale)

Centre for Stellar and Planetary Astrophysics – Monash University - Australia

Email: alessandro.chieffi@iaps.inaf.it

GREAT–ESF WORKSHOP

The metallicity distribution in the Milky Way discs

(Bologna, 29-31 May 2012)

H

He

CO

Fe

ZrBa

Th

Zn

Pb

N

Li

Be

B

F

NeSi

S

Ca

Ti

Ar Ni

1H 2H

3He 4He A=5

6LiA=5 7Li

A=5

A=8

9Be

11B10B

12C

A=8

A=8

13C

A=5

A=8

A=8

A=5

A=8

N

P

H

He

CO

Fe

ZrBa

Th

Zn

Pb

N

Li

Be

B

F

NeSi

S

Ca

Ti

Ar Ni

Kr

Mo Sn

Nd

Yb

Solar chemical composition

The Coulomb barrier prevents an easy fusion between charged particles: only a combination of high temperatures, high densities and long timescales may lead to a substantial amount of fusion.

Evidence

Even the fusion of the lightest nuclei, protons, requires

T > several 106 K ρ > several grams / cm3

to burn a significant amount of nuclei on a timescale shorter than the age of the Universe

These conditions are met only in stars

M

Basic flavor of the evolution of a star

From a nucleosynthetic point of view we can consider two main classes of stars:

Intermediate mass stars &

massive stars. (+Type Ia Supernovae)

M>10 MO reach TC = 1010 K , collapse & explode

M<10 MO form an e-degenerate core, lose their envelope and end up as white dwards

T c

c∝Mlog10T c∝

13

log10 c

H

HeC/OOSi

H-burning (T~ 4·107) He-burning (T~ 1.5·108) C-burning (T~ 7·108) Ne-burning (T~ 1.2·109) O-burning (T~ 1.8·109) Si-burning (T~ 2.8·109)

Hydrostatic Evolution

Massive stars

infalling matter

outgoing shock from rebounce

proto neutron star

ATTENTION: photodisintegrations activate for 30 KT=Qi.e. T(BK) = 0.4 Q (MeV)

NSE QSE 2QSE

ScTiFeCoNi

VCrMnTiFeSiSArCa

SiSArCaK

NeNaMgAlPCl

f(ρ,T,Ye) f(ρ,T,X

i)

He burn. C shell burn.

H burn.

Expl. O burn.&

Incomplete expl. Si burn.

Expl. O burn.

Incomplete expl. Si burn.

NSE ( complete expl. Si burn.)He & C shell burn (n-capt.

nucleosynthesis)

H

He

CO

Fe

ZrBa

Th

Zn

Pb

N

Li

Be

B

F

NeSi

S

Ca

Ti

Ar Ni

Kr

Mo Sn

Nd

Yb

Solar chemical composition

M

Basic flavor of the evolution of an intermediate mass star

InertCO

core

He burning shell

Intershell He+C+s

H burning shell H rich mantle

Neutrons produced by 2 processes: 13C(α,n)16O and 22Ne(a,n)25Mg

Main characteristics:The two burning shells cannot be active simultaneously

Matter freshly synthesized in the intershell is brought to the surface

13C(α,n)16OS-process nucleosynthesis

Active H burning

Active He burning

He ignition (Thermal Pulse)

He – C rich zone

H rich zone

XP < 4x10-4

n-fluence “s” process 13C(α,n)16O

n-fluence “s” process 13C(α,n)16O

12C(p,g)13N(e+v)13CH

H

14N

14N

14N

14N

N

N

N

N

N

N

Courtesy: S. Cristallo

PHYSICS OF ROTATIONSTRUCTURE

• Oblateness (interior, surface)‏• New structure equations

Von Zeipel Theorem

Meridional Circulation

Local conservation Meridional circulation

Advection of angular

momentum

Increase the gradient of angular velocity

Shear Instabilities

Transport of Angular Momentum

Transport of Chemical Species

Courtesy: G. Meynet Courtesy: G. Meynet

Thank You !