1. Nucleosynthesis in Pop III, Massive and Low-Mass Stars
Nobuyuki Iwamoto （Univ. of Tokyo）
with
H. Umeda, & K. Nomoto

2. Extremely metal-poor (EMP) stars ([Fe/H]<–2
Extremely metal-poor (EMP) stars ([Fe/H]<–2.5) may have abundance patterns created by Pop. III supernovae (SNe).
Surface chemical compositions observed in the most Fe-poor star HE are thought to be attributed to
single supernovae with M>~20-130M8 (Umeda & Nomoto 2003)
two (or more) supernovae with SNe of low mass and massive black-hole forming SNe (Limongi, Chieffi, & Bonifacio 2003)
Evolution of the observed low-mass star may be important.

3. McWilliam, Ryan, Spite, Cr Mn
trend Co Zn
[Fe/H]
[Fe/H]

4. Spectra of Supernovae & Hypernovae
94D
Ic: no H,
no strong He,
no strong Si
SiII Ia O Ca He
84L Ib
Hypernovae：
　　broad features
　　blended lines
　　“Large mass at high velocities”
more massive Ic
94I
Hyper　　-novae
97ef
98bw
more energetic
explosion

5. Light curves of Hypernovae & SNe Ic
log L (erg/s)
Radioactive Decay Ni Co Fe
C+O Star Models
98bw
97ef
94I
Mms
(M) 40 35 15
MC+O
13.8
10.0
2.1 EK
(1051erg) 30 20 1
M(56Ni)
0.5
0.15
0.07 43
98bw&CO138 42
97ef&CO100 41
94I&CO21
t (days)

6. Hypernova Nucleosynthesis
(1) M(Complete Si-burning)
(Zn, Co)/Fe
(Mn, Cr)/Fe
Fe/(O, Si)
(2) More ‐rich entropy
Zn/Fe Ge
(Ti, Ni)/Fe
(3) More O burns
(Si, S, Ca)/O
Normal SNe
Hypernovae

7. Normal SNe and hypernovae
Umeda et al. 2002
complete Si
burning
incomplete Si
burning
than
enhancement of
elements heavier
than Fe (Co and Zn)
For the same mass cut, mass ratio of
complete Si burning region to incomplete
Si burning region becomes larger.
a-rich
freeze-out

8. Umeda & Nomoto 2003 Cr
15M, E51=1 Mn
25M, E51=30
(Hypernova) Co Zn

9. Carbon-rich EMP Stars 2 1 [C/Fe] -1 -4 -3 -2 -1 0 [Fe/H]-1
[Fe/H]
Aoki et al. (2002)

10. C-Rich, Extremely Metal-Poor Star: CS22949-037 ([Fe/H]=– 4.0)
30M, E=2×1052erg
[Zn/Fe] ~ +0.7
Zn,Co enhancement
M(56Ni)~3×10-3M, M(BH)~8M
Energetic but relatively
faint supernova
Norris et al.
Dapagne et al.
C-rich, EMP stars may be formed by black-hole forming SNe.

11. Mixing and Fallback MBH ~ 6M Mixing ejecta Fallback
M=25M, E=3×1050erg
Umeda & Nomoto (2003)
Mixing
MBH ~ 6M
ejecta
Fallback

12. The Most Iron-Poor Star: HE0107-5240 (Chriestlieb et al. 2002)
[Fe/H] = －5.3
[C/Fe] = +4.0
[N/Fe] = +2.3
[Na/Fe] = +0.8
[Mg/Fe] = +0.2
[Ca/Fe] = +0.4
[Ti/Fe] = －0.4
[Ni/Fe] = －0.4
Umeda & Nomoto (2003) Nature, 422, 871
12C/13C>30
no s- & r- enhancement : no companion star
M = 25M E = 3×1050ergs
MHe = 8M C+N from He layer
MCO = 6M MBH
M(Fe) ~ 10-5M

13. Standard evolution of a 0.85M8 star
Initial composition: yield of Pop. III 25M8 supernova with explosion energy E=0.3x1051 erg (Umeda & Nomoto 2003)
0.486
ignition of He burning
0.45
0.4
0.35
H-rich
Envelope
He core HE
0.3
Mc/M8
=0.25

14. Elemental Abundances HE0107-5240 initial composition
after the first dredge-up in the standard evolution

15. Evolutionary Track of a 0
Evolutionary Track of a 0.85M8 star with mixing between H burning shell and He core
H-rich envelope
H-rich envelope
~ 5x107 yr/~108 yr
(lifetime on the RGB)
convective
convective
radiative
radiative
convective
He core
He core
onset of
proton mixing
H-rich envelope
convective
dredge-up
He core

16. Variation of Abundance Distributions after Proton Mixing
20Ne
23Na 1H
22Ne
19F
12C
16O
after 3900yr
14N
13C
Xp=10-2
D=106cm2/sec
20Ne
22Ne
23Na
19F
after 10000yr

17. Elemental Abundances 12C/13C = 43.5 HE0107-5240 initial composition
after the first dredge-up in the standard evolution
after proton mixing
12C/13C = 43.5

18. Results of Limongi et al. 2003
[F/Fe]~2.7
Fluorine might be important to understand the origin of HE

19. Summary: First Supernovae and EMP stars
EMP Stars: [Fe/H] < －2.5
Trends in [(Zn, Co, Mn, Cr)/Fe]
CN-rich Stars
HE (Christlieb et al.)
Na (F & Al) production
by the proposed internal process
Black-Hole Forming Supernovae
Variations in
Explosion Energy Rotation
Mixing & Fallback Binarity
Jets, …
High Energy, Jets
Mixing and Fallback
Na/O anti-correlation in globular cluster
(~20M–130M)