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Core Collapse SNe
Inma DomínguezMarco Limongi
Evolution of Massive Stars
Hydrostatic Nucleosynthesis
Explosion Mechanism
Explosive Nucleosynthesis
Contribution to the Chemical Evolution
-12-11-10
-9-8-7-6-5-4-3-2-1012
0 20 40 60 80 100 120 140 160 180 200
Atomic Weight
Lo
g M
as
s F
rac
tio
nBB CR neut.Novae IMS SNIISNIa s-r
Type II SNe Chemical Evolution of the Galaxy Type II SNe 16 < A < 50 and 60 < A < 90 16O 49Ti 60Ni 90Zr
BB = Big Bang; CR = Cosmic Rays; neut. = induced reactions in SNII;IMS = Intermediate Mass Stars; SNII = Core collapse supernovae;SNIa = Termonuclear supernovae; s-r = slow-rapid neutron captures
INTERPRETATION OF THE SOLAR SYSTEM ABUNDANCES
Evolutionary Properties of Massive Stars:
Progenitors of CCSNe
M > 12 M CCSNe
Central Conditions (T,) Ignition of ALL ExothermicNuclear Reactions
The stars is never in degenerate conditions along its evolution
),,(4
),,(),,(),,(
),,(4
1
4
2
2
4
i
igraviinuc
i
YTPPr
GmT
m
T
YTPYTPYTPm
L
YTPrm
r
r
Gm
m
P
STELLAR EVOLUTION EQUATIONS
1 Dimension Lagrangian Hydrostatic
Mixing-length theory
Ni
YYYvNlkjc
YYvNkjcYjct
Y
lklkj
jlkjAi
kkj
jkjAij
jjii
,........,1
),,(
),()(
,,,,
22
,,
STELLAR EVOLUTION EQUATIONS
+ Chemical Evolution
A
i
i
ii N
N
A
XY
Production + Destruction
For each time step
1000 (zones) systems of 4+N(isotopes) equations
High Computational Time
HYDROGEN BURNING - PP
4H He
1H + 1H 2H + e+ +
2H + 1H 3He +
3He + 3He 4He + 2 1H
PPI3He + 4He 7Be +
7Be + e- 7Li +
7Li + 1H 2 4He
7Be + 1H 8B +
8B 8Be + e+ +
8Be 2 4He
PPII PPIII
Proton-Proton Chain
Depending on T the different branchings become active.
In all cases the result is
4 1H 1 4He
HYDROGEN BURNING CNO
Cycle
12C + 1H 13N +
13N 13C + e+ +
13C + 1H 14N +
14N + 1H 15O +
15O 15N + e+ +
15N + 1H 12C + 4He (99%)
16O + (1%) T 3 107 K
When C and/or N and/or O are present CNO
16O + 1H 17F +
17F 17O + e+ +
17O + 1H 14N + 4He
CN
NO
During the conversion of H into He through the CNO cycle C and O are burnt and N is produced
Products of CNO C N O
HYDROGEN BURNING – ENERGY GENERATION
The CNO cycle is more efficient than he PP chain over a certain Tcritica
CNO
PP
From Hydrostatic Equilibrium Eq:4
2
R
MPc
TR
MTP 3
R
MTc Central Temperatura
scales with Total Mass
Massive stars H-burning CNO cycle
44 r
Gm
m
P
HYDROGEN BURNING - CONVECTIVE CORE
The Energy generated by the CNO-cycle depends strongly on T
High Energy Flux Increases Radiative Gradient A Convective core Develops
FacTdr
dT
rad34
3
Masssive stars burn H within a Convective core
At high T the main contribution to the Opacity comes from the Thomson Scattering
)1(2.0 HTh X
When the H decreases, the Opacity decreases and the Convective Core receeds and finally, at H-exhaustion, disappears
HYDROGEN BURNING – Ne-Na, Mg-Al Cycles
If during the central convective H-burning T are high enough log T=7.5-7.8
Active Ne-Na e Mg-Al cycles
20Ne + 1H 21Na +
21Na 21Ne + e+ +
21Ne + 1H 22Na +
22Na 22Ne + e+ +
22Ne + 1H 23Na +
23Na + 1H 20Ne + 4He
Ne-Na Cycle
24Mg + 1H 25Al +
25Al 25Mg + e+ +
25Mg + 1H 26Al +
26Al 26Mg + e+ +
26Mg + 1H 27Al +
27Al + 1H 24Mg + 4He
Mg-Al Cycle
Final results of the operation of these cycles Na-Na e Mg-Al
21Na & 25Mg practically burnt
22Ne is reduced by a factor 2
23Na & 26Mg increase by a factor 6 & 2, respectively
26Al produced (~10-7)
20Ne, 24Mg & 27Al do not change
STRUCTURE AT CENTRAL H-EXHAUSTION
The He-core is much more dense than the H-envelope because the mean molecular weight for 4He is greater than for 1H Matter within the He-core is more compact
778.1 714.1 333.1 5.0 1
1
OCHeH
i i
i
A
Z
He core H envelope
The synthesis of heavier isotopes increases the mean molecular weight and the structure becomes more compact
Convective envelope
H conv. core He conv. core
H burn.shell
He burn. shell
HeHe core
CO core
dup
HYDROGEN SHELL BURNING
At central H-exhaustion H-burning sets in a Shell outside the He-core.
HR diagram: the star moves to the red
A convective envelope forms, the inner border of this envelope reachs zones chemically modified by he central H-burning.
The 1st dredge-up occurs: material processed by nuclear reactions is transported to the surface
H exhaustion Start Conv. Env.
HELIUM BURNING – 3
At central H-exhaustion, the He core is mainly composed by 4He (98%) & 14N (1%)
Withouth Nuclear Energy generation within the core, it contracts and Tc increases
When Tc ~ 1.5 108 K Efficient He-burning
4He + 4He 8Be +
8Be 4He + 4He
At the beginning 4He 8Be and 8Be rapidly decays to 4He
4He + 4He 8Be +
8Be 4He + 4He
8Be + 4He 12C +
Later, at higher T and the equilibrium abundance of 8Be increases
and so increases the probability of the reaction 8Be + 4He producing 12C
3 4He 12C +
HELIUM BURNING – REACTIONS
Initially: 4He in 12C But when 12C abundance is significant and 4He abundance is
reduced, it is more likely that 4He is captured by 12C than by 4He:
3 4He 12C +
12C + 4He 12O +
16O + 4He 20Ne +
20Ne + 4He 24Mg +
3 4He Nuclear Cross Section depends markedly on T
Like H-burning (CNO cycle) He-burning occurs within a convective core
The first 2 reactions are more efficient
HELIUM BURNING: s-process
84Se
85Br
86Kr
83As 84As 85As
85Se 86Se
86Br 87Br
87Kr 88Kr
73Ge 74Ge 75Ge 76Ge
74As 75As 76As
72Ga 73Ga
77As
75Se 76Se 77Se 78Se 79Se 80Se 81Se 82Se
76Br 77Br 78Br 79Br 80Br 81Br 82Br 83Br
77Kr 78Kr 79Kr 80Kr 81Kr 82Kr 83Kr 84Kr
80As 81As78As 79As
78Rb 79Rb 80Rb 81Rb 82Rb 83Rb 85Rb84Rb
80Ge77Ge 78Ge 79Ge
79Ga76Ga 77Ga 78Ga74Ga 75Ga
n,
b-
b-
b-
In Massive during central He-burning, elements heavier than Fe are synthesized by the s-process.
s-process depends on free neutrons and the neutron abundance depends on Z The final s-element abundances scale with initial metallicity
14N + 4He 18F +
18F 18O + e+ +
18O + 4He 22Ne +
22Ne + 4He 25Mg + n
14N produced by the CNO cycle
HELIUM EXHAUSTION
The most abundant isotopes at central He-exhaustion:12C 16O 20Ne 25Mg 26Mg
The first three are produced by:
3 4He 12C +
12C + 4He 12O +
16O + 4He 20Ne +
25Mg & 26Mg come from the 14N-chain
14N + 4He 18F +
18F 18O + e+ +
18O + 4He 22Ne +
22Ne + 4He 25Mg + n
22Ne + 4He 26Mg +
12C, 16O, 20Ne, 25Mg & 26Mg are the most abundant isotopes and are produced by He-burning with the surface abundance
12C/16O ratio depends on the 12C + 4He 12O + nuclear cross section that it is still NOT well known at the energies of the He
burning. This ratio has a strong influence on the subsequent evolution
12C
16O20Ne
22Ne25Mg
26Mg
ex He c.c.H sh.
Conv. Envelope.
Core di CO
HELIUM EXHAUSTION: s-process elements
The most abundant elements are:
70Ge 74Se and 80Kr
Heavier nuclei, like 87Rb, 88Sr, 89Y, 90Zr are not expected to be produced
70Ge
80Kr
74Se
ex He c.c. Conv. Envelope.H sh.
Core di CO
At central He exhaustion, He burning moves to a shell just outside the CO core
The following evolution is characterized by the development of a convective He-burning shell limited by the CO core and by the H-burning shell.
The chemical composition of this shell, that will be active till the collapse, tends to get frozen because the evolution of the star is more and more rapid at the
advanced phases.
Convective envelope
H conv. core He conv. core
H burn.shell
He burn. shell
HeHe core
CO core
dup He conv.shell
HELIUM SHELL BURNING – CONVECTIVE SHELL
STRUCTURE at He-exhaustion
At central H-exhaustion, the is composed by a CO core, a He-shell and a rich H envelope
He core
H envelope
CO core
The two density gradients correspond to the border of the He core (~ 9 M) and to the border of the CO core (~ 6 M )
This density profile is important for the explosion properties
ADVANCED EVOLUTIONARY PHASES: NEUTRINO DOMINATED
Now the CO core, produced by the central He-burning, contracts During the contraction the and T within the core favours the production of thermal neutrinos produced by pair anhilation.
At T>109 K high energy photons produce e+e- pairs
eeThat suddenly recombine to produce a photon.BUT once over 1019 times, e+e- produces a neutrino-antineutrino pair
eeee times)10/1( 19
This energy sink increases along the subsequent phases up to the pre-collapse phase
Advanced evolutionary phases of massive stars are called
“neutrino dominated”
ADVANCED EVOLUTIONARY PHASES: NEUTRINO LUMINOSITY
From now on the energy losses:
Photons from the surface
Neutrinos from the center
Photon
Nuclear
Neutrino
Up to C central ignition the main energy losses are due to photons and after are due to neutrinos. As the nuclear energy gives the star what is lossing, it follows first the luminosity of photons, and after, the neutrino luminosity
108
EVOLUTIONARY TIMES
Mt
EL
nuc
nuc
Enuc is the energy per gram coming from nuclear reactions, If this is the only energy source in a star of mass M:
L
MEt nucnuc Nuclear time scale:
H burning: 4 1H 4HeM = 4 x 1.0078 – 4.0026 = 0.0287 AMU = 0.0287/4 AMU/nucleon = 0.007 AMU/nucleon
Enuc = 0.007 x 931.1 x 1.602 10-6 x 6.022 1023 = 6.44 1018 erg/g
1 AMU = 931.1 MeV : 1 MeV= 1.602 10-6 erg : NA = 6.022 1023 nucleon/g
He burning: 4 4He 16OM = 4 x 4.0026 – 15.9949= 0.0115 AMU = 0.0115/16 AMU/nucleon = 0.0009 AMU/nucleon
Enuc = 0.0009 x 931.1 x 1.602 10-6 x 6.022 1023 = 8.70 1017 erg/g
O burning: 2 16O 32S
M = 2 x 15.9949 – 31.9720= 0.0177 AMU = 0.0177/32 AMU/nucleon = 0.0005 AMU/nucleon
Enuc = 0.0005 x 931.1 x 1.602 10-6 x 6.022 1023 = 4.98 1017 erg/g
For fix mass, Luminosity and amount of fuel
08.0 13.0 H
O
H
He
t
t
t
tFrom models: 81056.5 11.0
H
O
H
He
t
t
t
t!
The luminosity increases drastically due to neutrino losses The evolutionary times are drastically reduced
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 nuc Evolutionary
times reduce dramatically
CARBON BURNINGCentral C combustion stars ~104 years after central He-
exhaustionTc ~ 7 108 K e c ~ 1 105 g/cm3
C-burning depends on the 12C/16O ratio left after central He burning, 12C()16O
on the amount of fuel
The formation of a Convective Core depends on the existence of a positive energy flux
12C abundances determines the nuclear energy generation rate
A Convective Core developsnuc >
NO Convective Core
nuc <
In general, for a fix 12C(,)16O reaction rate and mixing technics 12C abundance decreases for higher initial masses
In the 25M central carbon combustion occurs in radiative conditions
Synthesis of Heavy Elements
At high temperatures 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~ 9T
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
),,(NSEi eYTfY
=0.000,Ye=0.5000, 56Ni=0.038,Ye=0.481, 54Fe
=0.072,Ye=0.464, 56Fe=0.104,Ye=0.448, 58Fe
eY21
389 g/cm 10 K 105 T
MATTER PROPERTIES AT HIGH TEMPERATURE :NSE
The chemical composition of matter in NSE is a function of T Ye
When the neutronization changes
The nuclei with that neutron excess are favoured (with higher binding energies)
i
ii
ie X
A
ZY
PRE-SUPERNOVA MODEL: CHEMICAL COMPOSITION
Burning Site Main Products
Si Burning 54Fe, 56Fe, 55Fe, 58Ni, 53Mn
O Conv. Shell 28Si, 32S, 36Ar, 40Ca, 34S, 38Ar
C Conv. Shell 20Ne, 23Na, 24Mg,25Mg, 27Al + s-process
He Centrale 16O, 12C + s-process
He Shell 16O, 12C
H Centrale+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
ale
He
Sh
ell
H S
he
ll
H C
en
tra
le
16O28Si
20Ne
12C
4He1H
“Fe”
Studying the different isotope abundances in detail is possible to know from which burning phase they come from or the interior region of the star where they were produced
PRE-SUPERNOVA MODEL: Fe-CORE STRUCTURE
Fe/SiSi/O
CO/He
He/H
16O
20Ne
12C
28Si“Fe”
EXPLOSION
ergRR
GMEbind 1011
5
3 53
12
2
KmR 102
The gravitational collapse of a stars with M 12 M could liberate an energy of
Most of this energy increases the electron energy and, after electron captures, is converted in neutrino energy
Just a small fraction is used to eject (kinetic energy) the envelope
So, the key question is to find a mechanism able to transform a small fraction of the binding energy left during the collapse in kinetic energy of the envelope with the observed velocities ( 104 km/s)
Explosive Nucleosynthesis and Chemical Yields
Explosion Mechanism Still Uncertain
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
•Explosion: 1D PPM Lagrangian Hydrocode (Collella & Woodward 1984)
•Explosive Nucleosynthesis: same nuclear network adopted in the hydrostatic evolutions
16O28Si
20Ne
12C
4He1H
“Fe”
Pis
ton S
i bu
rnin
g
O c
on
v. S
hel
l
C c
on
v. S
hel
l
He
Cen
tral
He
Sh
ell
H S
hel
l
H C
entr
al
EXPLOSIVE NUCLEOSYNTHESIS
Passing through the envelope the Shock Wave increases the density and temperature and nuclear reactions occur
Y
Yi
),( Tfi
We may define the burning time-scales for the available fuels :
These time scales are determined by the corresponding destructive reactions
Si, O, Ne, C, He and H
Assuming the explosion time ~1s
burning Si K 104 9T
burning O K 103.3 9T
burning Ne K 101.2 9T
burning C K 109.1 9T
burning Heg/cm 10 35
Burning products are similar to those obtained in hydrostatic burning
He-explosive burning is not efficient in SNII
EXPLOSIVE NUCLEOSYNTHESIS
Analyzing the most eficient processes:
EXPLOSIVE CARBON BURNING: K109.1 9TProducts: 20Ne, 23Na, 24Mg,25Mg, 26Mg
EXPLOSIVE NEON BURNING: K101.2 9T
Products: 16O, 24Mg + 27Al, 29Si, 30Si, 31P, 35Cl, 37Cl
EXPLOSIVE OXYGEN BURNING: K100.4 9T
Products: 28Si, 32S, 36Ar, 40Ca + 34S, 38Ar
Still out of NSE: Products are similar to those from hydrostatic burning
K103.3 9T
K103.3 9T Starting NSE (direct and inverse process)
2 clusters at quasi-NSE separated by A44.
No connection between the 2 clusters
A=44
A=45
Clusters di equilibrio
28Si
56Fe
),,,(QSEi
Qie YYTfY
EXPLOSIVE NUCLEOSYNTHESIS
EXPLOSIVE INCOMPLETE SILICON BURNING:
K100.5 9T
Products: 36Ar, 40Ca + 56Ni(56Fe), 54Fe, 52Fe(52Cr),51Cr(51V), 55Co(55Mn), 57Ni(57Fe), 58Ni
At this T the 2 clusters connect at A44.
Most of the matter A<44 just part of 28Si reachs the upper cluster
A=44
A=45
Clusters di equilibrio
28Si
56Fe
),,,( 28i SiYTfY e
EXPLOSIVE COMPLETE SILICON BURNING:
K100.5 9T
At this high temperature: NSE !!!!!!
All 28Si is burnt to Fe-peak elements. Abundances depend on neutronization !!
For NZ 56Ni is the most abundant nuclei
),,(i eYTfY
Full NSE
Products: Iron Peak Nuclei
EXPLOSIVE NUCLEOSYNTHESIS
During the explosion Temperatures are very high
It could be assumed that matter behind the shock is radiation dominated
43
3
4aTREexpl
The shock propagates in all directions (sphere)
Each radial coordinate in the presupernova model will reach a maximum temperature
41
34
3
aR
ET
PSN
explmax
TR,= Location and T of the shock
Changes in T and following expansion are crucial for the nucleosynthesis
EXPLOSIVE NUCLEOSYNTHESIS
For Eexpl=1051 erg we could infer in the presupernova model which regions
(volumes) experience each burning
3700 5000 6400 11750 13400
Complete Si burning
Incomplete Si burning
Explosive Oxygen
Explosive Neon
Explosive Carbon
Un
tou
ch
ed
Zo
ne
K100.5 9 K100.4 9 K103.3 9 K101.2 9 K109.1 9
NSE QSE 1cluster
QSE 2cluster
Ne,Na,MgMg,Al, P, ClSi,S,Ar,K,Ca
Cr,V,Mn,Fe
Sc,Ti,Fe,Co,Ni
EXPLOSIVE NUCLEOSYNTHESIS: PROGENITOR
Influence of the Progenitor:
1) M-R RELATION (= density profile):
Fix the mass inside a certain volume
2) Ye (neutronization):
In those zones that reach NSE or QSE determines the rate between protons and neutrons
3) Chemical Composition :
For those zones that experience normal burnings (ie. Explosive Carbon e Neon burnings) fix the amount of fuel available.
T=5 109 K, = 108 g/cm3, Ye=0.50 56Ni=0.63 – 55Co=0.11 – 52Fe=0.07 – 57Ni=0.06 – 54Fe=0.05
T=5 109 K, = 108 g/cm3, Ye=0.49 54Fe=0.28 – 56Ni=0.24 – 55Co=0.16 – 58Ni=0.11 – 57Ni=0.08
MASS CUT
The Mass Cut depends on the piston initial velocity
Mass Cut
During the explosion internal zones fall back. At some point part of the matter is Expanding and some Collapsing
Depending on v compare to vesc
The mass coordinate at the bifurcation is defined as the Mass Cut
1.110
1.144
1.170
1.220
1.250
1.263
The lack of a explosion model makes the MASS CUT and the KINETIC ENERGY quantities that depend on parameters (initial energy or piston initial velocity and place at which the
explosion is started)
In general, for greater initial velocities Smaller Mass Cut Greater kinetic Energies
cutkin0pist M ,E v ,M
16O
20Ne
12C
28Si
4He
1H
Pre = DottedPost = Solid
Ox Nex Cx UntouchedSi-c Si-i
FallB
ack
EXPLOSION PROPERTIES: CHANGES IN CHEMESTRY
The changes in composition due to the explosion occur only at the most internal ~3.1 M
Outside the chemical composition remains untouched. It is that from the hydrostatic burning
The complete explosive Si burning and part ot the incomplete explosive Si burning fall back to the compact remant
Mass Cut
v0=1.5550 109 cm/s Mcut=1.89 M Ekin=1.14 foeTaken:
MASS CUT CALIBRATION: LIGHT CURVES
From the LC we obtain information for the Mcut
56Ni
56Co
TotalFeCoNi 565656
56Ni=0.15 M
56Ni=0.07 M
56Ni=0.01 M
8.8 111
Based on the Bolometric LCs and on the distance, we can deduce the amount of 56Ni produced during the explosion
After an initial phase, different for the different types of SNe, the LC is powered by the photons produced by the radioactive decay
56Ni is produced in the most internal zone depends critically on the Mass Cut The Mass Cut may be choose to reproduce a certain amount of 56Ni in agreement with the observations.
The theoretical kinetic energy must be compatible with the observed
MASS CUT CALIBRATION vs INITIAL MASS
From the observed initial mass of the progenitor we may obtain an empirical relaction between this mass and the 56Ni produced (or Mcut)
Few estimations of the progenitor initial mass from the observations
Similar masses give very different 56Ni masses
)()(56iMfNiM )( icut MfM
PROBLEMS !!!!
Hamuy et al. 2003
CHOOSING A MASS CUT
1) FLAT Case: All masses produce the same 56Ni mass = 0.05 M For each model a different mass cut is chosen in order to reproduce this amount of Ni
2) TREND Case: We adopt a relation between Initial Mass and 56Ni Mass:
Mi (M)
M(56Ni) (M)
13 0.15
15 0.10
20 0.08
25 0.07
30 0.05
35 0.05
PRODUCTION FACTORS
To compare with Solar Abundances we introduce the Production Factor
Mtot
Mcut
Suni
Mtot
Mcut
i
i
dmX
dmX
PF
Two isotopes with the same Production Factor
Same Rate as in the Sun
Oxygen is produced only by Type II SNe and is the most abundant element produced by SNII Oxygen Production Factor is a Good Metallicity indicator
It is useful to normalize all PF to that of Oxygen to show wich isotopes follow Oxygen (Z)
Dots: 13 – 15 – 20 – 25 – 30 – 35 M
Solid line: Salpeter Mass FunctionFlat 56Ni => 0.05 M
INTEGRATED YIELDS (Elements)
Yields from 13-35 M + Salpeter Mass FunctionIt is assumed that all masses produce the same amount of 56Ni (FLAT)
We consider “Solar Scaled” with respect to O all elements with a PF within a factor 2 of the O PF
The yields produced by a generation of massive stars integrated by a Salpeter IMF
depend mainly on the yields coming from a 20-25 M star
Production of Fe the percentage of SNIa, relative to SNII, has been fixed by requiring that PFFe=PFO
Open circles = No SNIa Filled circles = 12% SNIa
1)SNIa contribute only to the Solar System abundances of nuclei in the range Ti-Ni
2)The inclusion of SNIa brings 50Ti and 54Cr into the band of compatibility 50Ti and 54Cr become scaled solar compared to O
Contribution of Type Ia SNe
3) 14N and lot of heavy elements come from AGB stars
CONCLUSIONS
Assuming a Salpeted IMF the efficiency of enriching the ISM with heavy elements is:
H: decreased by f=0.64He: increased by f=1.47Metals: increased by f=6.84
For each solar mass of gas
returned to the ISM
Massive Stars are responsible for producing elements from
12C (Z=6) up to 90Zr (Z=40) + r-elements
Pre/Post SN models and explosive yields available at http://www.mporzio.astro.it/~limongi
Alessandro Chieffi & Marco Limongi (ApJ 1998-2007)
with mass loss: 11 -120 M
Uncertainties in the computation PreSN Models
Extension of the Convective Core (Overshooting, Semiconvection)
Mass Loss
Uncertainties in the computation of the Explosion Models
Explosion itself
Piston:
Mass-cut - Mini
56Ni (LC)
Energy (vexp)
Navegamos sin rumbo a través del obscuro Océano Cósmico
¿ Podemos ganar la liga de campeones ?
Estrellas y planetas en un espacio infinito… ¿ Tiene sentido nuestra presencia en el Universo ?
IDEAL ORCEMANby C. Hernández
CHEMICAL ENRICHMENT BY A GENERATION OF MASSIVE STARS
The 25 M solar model could be considered as the “typical” case, representative of stars from 13 to 35 M
If we compute the YIELDS (ejected abundances in solar masses) of the different isotopes produced by a grid of models (~13 to 35 M), we could compute the chemical contribution of a generation of Massive Stars to the ISM
These YIEDS are ingredients in a Chemical Evolution Model for the Galaxy, includes SFR, IMF & Infall
In principle, the chemical solar distribution is a consequence of different generations of stars with different initial compositions
The metallicity of the ISM is expected to increse continously and with longer time-scales than the evolutionary time of the stars that contributes to the chemical enrichment
We expect that the YIELDS of a generation of masive solar metallicity stars explain the solar distribution
The only elements that vary between case “Flat” and case “Trend” are Fe and Ni and, at a smaller extent also Ti, Co and Zn (i.e. elements produced in the deep layers of the exploding mantle)
The majority of the elements have PFs compatible with that of O show a scaled solar distribution
Flat 56Ni => 0.05 M
13 15 20 25 30 35 M
processes
Int. Mass Stars
Int. Mass Stars
Trend 56Ni => 0.15–0.10–0.075-0.07–0.05–0.05 M
Integrated Yields adopting a different Mi-M(56Ni) relation
The Final Fate of a Massive Star with mass loss: 11 -120 M
No Mas
s Loss
Final Ma
ss
He-Cor
e Mass
He-CC Mass
CO-Core Mass
Fe-Core Mass
WNLWNE
WC/WO
Remnant Mass
Neutron Star
Black Hole
SNII SNIb/c
Fallback
RSG
Z=Z
E=1051 erg
Initial Mass (M)
Mass (M)
Limongi & Chieffi, 2007
Individual Yields
Different chemical composition of the ejecta for different masses
Averaged Yields
Yields averaged over a Salpeter IMF 2.35 mm )(
Global Properties:
Initial Composition (Mass Fraction)
X=0.695Y=0.285Z=0.020
Final Composition (Mass Fraction)
X=0.444 (f=0.64)Y=0.420 (f=1.47)Z=0.136 (f=6.84)
Mrem=0.186
Observed MPro smaller than LC models predict
Li et al.Smartt et al.van Dyk et al.
Initial Mass Function
mu~ 100 M; ml ~ 0.1 M
mrem Stellar evolution
IMF ≈ Present Day MF for massive stars
IMF ...universal?
Definitions
AMU (atomic mass unit, mu) 1/12 mass of 12C muc2 = 931.478 MeV
Cross section: Probability per pair of particles of occurrences of a reaction cm2
cm3 /s
