robert izzard - ast.cam.ac.ukrgi/doc/talks/torino_gallino-2008.pdf · simulating populations of...
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Simulating Populations of CEMPs
Robert IzzardUniversité Libre de Bruxelles
University of Utrecht
Evert GlebbeekMcMaster University
Onno PolsUniversity of Utrecht
Richard StancliffeMonash University
What are CEMP stars?Carbon-Enhanced [C/Fe] > 1
Metal-Poor [Fe/H] . −2
Mostly giants log g . 4
What are CEMP stars?Carbon-Enhanced [C/Fe] > 1
Metal-Poor [Fe/H] . −2
Mostly giants log g . 4
[C/Fe] vs [Fe/H] (SAGA)
-2
-1
0
1
2
3
4
-6 -5 -4 -3 -2 -1 0 1
[C/F
e]
[Fe/H]
[C/Fe] vs [Fe/H] (SAGA)
-2
-1
0
1
2
3
4
-6 -5 -4 -3 -2 -1 0 1
[C/F
e]
[Fe/H]
CEMPs
EMPs
[C/Fe] vs [Fe/H] (SAGA)
-2
-1
0
1
2
3
4
-6 -5 -4 -3 -2 -1 0 1
[C/F
e]
[Fe/H]
Models
Z=10-4
[Fe/H]=-2.3
Selectionlog g<4
CEMPs
EMPs
Model 1: Single Stars
Karakas+Lattanzio L = L(Mc, Menv)
log R ∝ log L
λ = λ(M, Z)
etc.
Model 1: Single Stars
Karakas+Lattanzio L = L(Mc, Menv)
log R ∝ log L
λ = λ(M, Z)
etc.
+
13C(α, n)
s(Mc, NTP
Z, 13C)
Model 1: Single Stars
Karakas+Lattanzio L = L(Mc, Menv)
log R ∝ log L
λ = λ(M, Z)
etc.
+
13C(α, n)
s(Mc, NTP
Z, 13C)
11,000,000
Binary Star Model
Results
Num
ber
ofSta
rs
Results
Num
ber
ofSta
rs
Results
Num
ber
ofSta
rs
CEMP/EMP ratio (observed ∼ 20%)
0 2 4 6 8 10 12 14 16
Mod
el S
et
CEMP/EMP ratio (%)
CEMP/EMP ratio (observed ∼ 20%)
0 2 4 6 8 10 12 14 16
Mod
el S
et
CEMP/EMP ratio (%)
"Default" physics
CEMP/EMP ratio (observed ∼ 20%)
0 2 4 6 8 10 12 14 16
Mod
el S
et
CEMP/EMP ratio (%)
Nelemans Common Envelope Prescription
Common Envelope α
CEMP/EMP ratio (observed ∼ 20%)
0 2 4 6 8 10 12 14 16
Mod
el S
et
CEMP/EMP ratio (%)
Bondi-Hoyle α
CEMP/EMP ratio (observed ∼ 20%)
0 2 4 6 8 10 12 14 16
Mod
el S
et
CEMP/EMP ratio (%)
Extra DUP (2004 prescription)
CEMP/EMP ratio (observed ∼ 20%)
0 2 4 6 8 10 12 14 16
Mod
el S
et
CEMP/EMP ratio (%)
Reimers η=0.1,1,5; Van Loon
CEMP/EMP ratio (observed ∼ 20%)
0 2 4 6 8 10 12 14 16
Mod
el S
et
CEMP/EMP ratio (%)
Common Envelope Accretion 0.01-0.05 M⊙
CEMP/EMP ratio (observed ∼ 20%)
0 2 4 6 8 10 12 14 16
Mod
el S
et
CEMP/EMP ratio (%)
No Thermohaline Mixing
CEMP/EMP ratio (observed ∼ 20%)
0 2 4 6 8 10 12 14 16
Mod
el S
et
CEMP/EMP ratio (%)
Menv,min for DUP = 0 M⊙
CEMP/EMP ratio (observed ∼ 20%)
0 2 4 6 8 10 12 14 16
Mod
el S
et
CEMP/EMP ratio (%)
Menv,min=0 M⊙
; λmin=0.8
CEMP/EMP ratio (observed ∼ 20%)
0 2 4 6 8 10 12 14 16
Mod
el S
et
CEMP/EMP ratio (%)
Menv,min=0 M⊙
; Enhanced 3DUP
∆MCE=0.05 M⊙
; No Thermohaline
CEMP C-distributionN
um
ber
ofSta
rs
1 1.5 2 2.5 3 3.5
[12C/56Fe]
1 1.5 2 2.5 3 3.5 4 4.5
[12C/56Fe]
thermohaline no thermohaline
s-process: cake not for eatingN
um
ber
ofSta
rs
13C efficiency s
s = 1
s = 1
100
-0.5 0 0.5 1 1.5 2 2.5 3 1 1.5 2 2.5 3 3.5
0 1 2 3 4
[Ba/56Fe]
0 0.5 1 1.5 2 2.5 3 3.5
[Pb/56Fe]
Conclusion: Problems
◮ Conspiracy of parameters?
◮ Need extra C even up to [Fe/H] ∼ −2 : how ?
(Flash mixing?)
◮ Richard Stancliffe finds 3DUP at 0.85 M⊙,
Z = 10−4 with Cambridge code . . . anyone else?
Menv,min < 0.5 M⊙?
◮ Observational selection effects?
◮ Trust the abundances? (3D, non-LTE?)
◮ Other solutions . . .
but beware the NEMPS!
Extra slides (just in case!)
SAGA distributions
0
10
20
30
40
50
60
-2.8 -2.7 -2.6 -2.5 -2.4 -2.3 -2.2 -2.1 -2 -1.9 -1.8
Num
ber
of S
tars
[Fe/H]
a[Fe/H] - All
[Fe/H] (C measured)
0 5
10 15 20 25 30 35 40 45 50
-0.5 0 0.5 1 1.5 2 2.5 3 3.5 4
Num
ber
of S
tars
logg
blog g
log g (C measured)
0
10
20
30
40
50
60
70
80
90
-1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5
Num
ber
of S
tars
[C/Fe]
c
0 10 20 30 40 50 60 70 80 90
100
-4 -3.5 -3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1
Num
ber
of S
tars
[C/H]
d
Number of (C)EMPs: log g
0 5
10 15 20 25 30 35 40 45 50
-0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 0
0.1
0.2
0.3
0.4
0.5
0.6N
(C)E
MP
NC
EM
P / N
EM
P
log g
aNCEMP / NEMP
NEMPNCEMP
Number of (C)EMPs: [Fe/H]
0 5
10 15 20 25 30 35 40 45 50 55
-2.8 -2.7 -2.6 -2.5 -2.4 -2.3 -2.2 -2.1 -2 -1.9 -1.8 0.1
0.15
0.2
0.25
0.3
0.35N
(C)E
MP
NC
EM
P / N
EM
P
[Fe/H]
b
CEMP N-distribution: extra mixing or
flash?
Num
ber
ofSta
rs
0 0.5 1 1.5 2 2.5 3
[14N/56Fe] 0 0.5 1 1.5 2 2.5 3
[14N/56Fe]
thermohaline no thermohaline
C vs N
0
0.2
0.4
0.6
0.8
1
1 1.5 2 2.5 3
[12C/56Fe]
0
0.5
1
1.5
2
2.5
[14N
/56Fe
]
Ba vs Pb
0
0.2
0.4
0.6
0.8
1
0.5 1 1.5 2 2.5
[Ba/56Fe]
0.5
1
1.5
2
2.5
3
[Pb/
56Fe
]