NUCLEOSYNTHESIS IN STELLAR EVOLUTION AND EXPLOSIONS: ABUNDANCE YIELDS FOR CHEMICAL EVOLUTION. MASSIVE STARS Marco Limongi INAF – Osservatorio Astronomico di Roma, ITALY and Centre for Stellar and Planetary Astrophysics Monash University – AUSTRALIA Email: [email protected]Alessandro Chieffi Work with:
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Marco Limongi INAF – Osservatorio Astronomico di Roma, ITALY and
NUCLEOSYNTHESIS IN STELLAR EVOLUTION AND EXPLOSIONS: ABUNDANCE YIELDS FOR CHEMICAL EVOLUTION. MASSIVE STARS. Marco Limongi INAF – Osservatorio Astronomico di Roma, ITALY and Centre for Stellar and Planetary Astrophysics Monash University – AUSTRALIA Email: [email protected]. Work with:. - PowerPoint PPT Presentation
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NUCLEOSYNTHESIS IN STELLAR EVOLUTION AND EXPLOSIONS: ABUNDANCE YIELDS FOR
CHEMICAL EVOLUTION. MASSIVE STARS
Marco LimongiINAF – Osservatorio Astronomico di Roma, ITALY
Massive Stars, those massive enough to explode as supernovae, play a key role in many fields of astrophysics:
Evolution of Galaxies:
Light up regions of stellar birth induce star formation
Production of most of the elements (those necessary to life)
Mixing (winds and radiation) of the ISM
Production of neutron stars and black holes
Cosmology (PopIII):
Reionization of the Universe at z>5
Massive Remnants (Black Holes) AGN progenitors
Pregalactic Chemical Enrichment
High Energy Astrophysics:
Production of long-lived radioactive isotopes: (26Al, 56Co, 57Co, 44Ti, 60Fe)
GRB progenitors
The understanding of these stars, is crucial for the interpretation of many astrophysical objects
Outline
Basic PreSN Evolutionary Properties of Massive Stars and Their Uncertainties
Explosive Nucleosynthesis and its uncertainties
Present Status of the presupernova and explosion modelling of Massive Stars
Comparison among available yields
Strategies for improvements
H Conv. core
CNO Cycle
H burning
Mmin(O) = 14 M
t(O)/t(H burning): 0.15 (14 M ) – 0.79 (120 M)
MASS LOSS
t=2 107 yr
1H 4He
CNO 13C,14N, 17O
NeNa,MgAl 23Na, 26Al
Hs=0.695Hes=0.285
Cs=3.18 10-3
Ns=1.16 10-3
Os=1.00 10-2
1H 4He
CNO 13C,14N, 17O
NeNa,MgAl 23Na, 26Al
t=3.6 106 yr
1H 4He
CNO 13C,14N, 17O
NeNa,MgAl 23Na, 26Al
t=2.7 106 yr
WIND
WIND
Hs=0.566Hes=0.414
Cs=8.42 10-5
Ns=1.30 10-2
Os=7.18 10-4
26Als=2 10-6
t=6.8 106 yr
1H 4He
CNO 13C,14N, 17O
NeNa,MgAl 23Na, 26Al
Hs=0.194Hes=0.786
Cs=1.18 10-4
Ns=1.34 10-2
Os=1.59 10-4
26Als=7 10-6
WNL/yrM 1010 O46 M
/yrM 1010 O46 M
Major Uncertainties in the computation of core H burning models:
Extension of the Convective Core (Overshooting, Semiconvection)
Mass Loss
Both influence the size of the He core that drives the following evolution
3+
12C(,)16O
He burning
The properties of core He burning mainly depend on the size of the He core
M ≤ 35 M RSG
M > 35 M BSG
t=2.0 107 yr t=1.5 106 yr
11
4He 12C, 16O22Ne, s-proc
4He, 14N
t=6.8 106 yr t=5.3 105 yr
4He, 14N
4He 12C, 16O22Ne, s-proc
25 Hs=0.649Hes=0.331
Cs=2.00 10-3
Ns=4.37 10-3
Os=7.86 10-3
Hs=0.000Hes=0.516
Cs=0.397Ns=0.000Os=0.06
4He, 12C
4He 12C, 16O22Ne, s-proc
t=3.6 106 yr t=3.6 105 yr
WNLWNE
WC
60120
t=2.7 106 yr t=3.0 105 yr
4He, 12C4He 12C, 16O
22Ne, s-proc
Hs=0.000Hes=0.422
Cs=0.432Ns=0.000Os=0.119WNL
WNEWC
4,610 M
310M
5.410M510M
4,610 M
410M
5.410M
7.4,510 M
Major Uncertainties in the computation of core He burning models:
Extension of the Convective Core (Overshooting, Semiconvection)
Central 12C mass fraction (Treatment of Convection + 12C(,)16O cross section)
Mass Loss (determine which stars explode as RSG and which as BSG)
All these uncertainties affect the size of the CO core that drives the following
evolution
22Ne(,n)25Mg (main neutron source for s-process nucleosynthesis)
Advanced burning stages
Neutrino losses play a dominant role in the evolution of a massive star beyond core He burning
At high temperature (T>109 K) neutrino emission from pair production start to
become very efficienteeee
L
MEt nucnuc Evolutionary times
reduce dramatically
costL
LL 108 1010
After core He burning
At Pre-SN stage
M < 30 M Explode as RSG
M ≥ 30 M Explode as BSG
Synthesis of Heavy Elements
At high tempreatures a larger number of nuclear reactions are activated
Heavy nuclei start to be produced
C-burning K 10~ 9T Ne-burning K 103.1~ 9T
Synthesis of Heavy Elements
O-burning K 102~ 9TWeak Interactions become efficient
Efficiency scales inversely with the mass
Synthesis of Heavy Elements
At Oxygen exhaustion K 105.2~ 9T Balance between forward and reverse reactions for
increasing number of processes a + b c + d
At Oxygen exhaustion
K 105.2~ 9T
Si
Sc
Equilibrium
At Si ignition
K 105.3~ 9T
Out of Equilibrium
Equilibrium
Partial Eq.
Out of Eq.
At Si ignition(panel a + panel b)
K 105.3~ 9T
A=44A=45
Eq. Clusters
28Si
56Fe
56,57,58Fe, 52,53,54Cr, 55Mn, 59Co, 62Ni
NSE
Ca),(K
Sc),(Sc Ti),(Ca
Ti),(Ca Ti),(Sc
Ti),(Ti Ti),(Ca
Ti),(Ca Ca),(Sc
Sc),(Ca Ca),(Ca
4441
45444643
45414544
45444542
46424444
45424443
p
nn
p
nn
pn
pn
He
CO
Ne/OO
Si
“Fe”
H
He
CO
Ne/O OSi
“Fe”
H
He
CO
Ne/O O Si“Fe”
H
He
CO
Ne/O OSi “Fe”
H
11 M 25 M
60 M 120 M
103 yr 3yr0.3yr 5 days
Burning Site Main Products
Si Burning 56,57,58Fe, 52,53,54Cr,
55Mn, 59Co, 62Ni
O Conv. Shell 28Si, 32S, 36Ar, 40Ca, 34S, 38Ar
C Conv. Shell 20Ne, 23Na, 24Mg,25Mg, 27Al + s-process
He Central 16O, 12C + s-process
He Shell 16O, 12C
H Central+Shell
14N, 13C, 17O
Si
bu
rnin
g(C
en
t.+
Se
hll
)
O c
on
v.
Sh
ell
C c
on
v.
Sh
ell
He
Ce
ntr
al
He
Sh
ell
H S
he
ll
H C
en
tra
l
16O28Si
20Ne
12C
4He1H
“Fe”
Chemical Composition at the PreSN stage
Final Masses at the PreSN stage
No Mas
s Loss
Final Ma
ss
He-Cor
e Mass
He-CC Mass
CO-Core
Mass
Fe-Core Mass
WNLWNE
WC/WO
RSG
Radius
WIND
HEAVY ELEMENTS
Major Uncertainties in the computation of the advanced burning stages:
Treatment of Convection (interaction between mixing and local burning, stability criterion behavior of convective shells final M-R relation explosive nucleosynthesis)
Computation of Nuclear Energy Generation (minimum size of nuclear network and coupling to physical equations, NSE/QSE approximations)
Weak Interactions (determine Ye hydrostatic and explosive nucleosynthesis behavior of core collapse)
Nuclear Cross Sections (nucleosynthesis of all the heavy elements)
Neutrino Losses
Partition Functions (NSE distribution)
Explosive Nucleosynthesis and Chemical Yields
Explosion Mechanism Still Uncertain
Piston
The explosion can be simulated by means of a piston of initial velocity v0, located near the edge of the iron core
v0 is tuned in order to have a given amount of 56Ni ejected and/or a corresponding final kinetic energy Ekin
Present Status of the presupernova and explosion modelling of Massive Stars
Databases of Cross Sections
Experimental:
Caughlan et al. (1985)Caughlan & Fowler (1988)Angulo et al. (1999) NACREBao et al. (2000): (n,) reactions Iliadis et al. (2001): (p,) reactionsJaeger et al. (2001): 22Ne(,n)25MgKunz et al. (2001): 12C(,)16OFormicola et al. (2004) LUNA collaboration: 14N(p,)15O LENA collaboration: 14N(p,)15O