The i process and CEMP stars - INDICO-FNAL (Indico)CEMP stars: heavy elements Lugaro et al. (2012),...
Transcript of The i process and CEMP stars - INDICO-FNAL (Indico)CEMP stars: heavy elements Lugaro et al. (2012),...
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Theiprocessand
CEMPstars
Credit:HST/NASA/ESA
MelanieHampel
MonashUniversity
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Withthanksto…
Credit:HST/NASA/ESA
RichardJ.Stancliffe
MariaLugaro
(Budapest)
BradleyMeyer
(Clemson)
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CEMPstars:heavyelements
Lugaroetal.(2012),datafromMasseronetal.(2010)
highBa
highBaandEu
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CEMPstars:heavyelements
Lugaroetal.(2012),datafromMasseronetal.(2010)
CEMP-s
CEMP-s/r,-r/s,-r+s,…,-i
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FormaRonofCEMP-sstars
1 2
MSMS
Credit:CarloAbate
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FormaRonofCEMP-sstars
Credit:CarloAbate
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FormaRonofCEMP-sstars
1 2
white dwarfMS
CEMP star
Credit:CarloAbate
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BinaryevoluRon+AGBnucleosynthesis?
Abateetal.(2015)
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BinaryevoluRon+AGBnucleosynthesis?
Abateetal.(2015)
Atomicnumber
CEMP-s
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BinaryevoluRon+AGBnucleosynthesis?
Abateetal.(2015)
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BinaryevoluRon+AGBnucleosynthesis?
Abateetal.(2015)
Eu
[hs/ls]
heavyRE
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BinaryevoluRon+AGBnucleosynthesis?
Abateetal.(2015)
Atomicnumber
CEMP-s
CEMP-s/r
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R-processpre-enhancement?
Lugaroetal.(2012)
IniRal
r-process
enrichment:
atleast
[r/Fe]>1dex
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R-processpre-enhancement?
Bisterzoetal.(2012)
IniRal
r-process
Enrichment:
[r/Fe]=1.5dex
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R-processpre-enhancement?
Bisterzoetal.(2012)
IniRal
r-process
Enrichment:
[r/Fe]=1.5dex
[hs/ls]
heavyRE
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R-processpre-enhancement?
Bisterzoetal.(2012)
IniRal
r-process
Enrichment:
[r/Fe]=1.5dex
HowdoCEM
P-s/rform?
??
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R-processpre-enhancement?
Bisterzoetal.(2012)
IniRal
r-process
Enrichment:
[r/Fe]=1.5dex
Modifiednucleosynthesis?
Intermediateneutroncaptureprocess?
HowdoCEM
P-s/rform?
??
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iprocess:n≈1015cm-3
15 2010
slow
neutron
captures
n≈107cm-3
rapid
neutron
captures
n>1020cm-3
intermediate
neutron
captures
n≈1015cm-3
logn
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sprocess:n=107cm-3
1.0e-2
1.0e-3
1.0e-4
1.0e-5
1.0e-6
1.0e-7
1.0e-8
1.0e-9
1.0e-10
1.0e-11
1.0e-12
1.0e-1t = 3.15e+12 sT = 1.5e+08 Krho = 1600 g/ccn = 1.0e+07 /cctau = 5.0 /mb
44 46 48
50
52
54 56
58
60
62 64
66 68
70 72 74 76
78
80 82
84
86 88
90 92
94
96
34
36
38
40
42
44
46
48
50
52
54
56
58
60
62
64
Z
N
massfracRon
low
high
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HigherneutrondensiRes:n=1010cm-3
1.0e-2
1.0e-3
1.0e-4
1.0e-5
1.0e-6
1.0e-7
1.0e-8
1.0e-9
1.0e-10
1.0e-11
1.0e-12
1.0e-1t = 2.94e+09 sT = 1.5e+08 Krho = 1600 g/ccn = 1.0e+10 /cctau = 4.6 /mb
44 46 48
50 52
54
56
58
60 62
64 66
68 70
72 74 76
78
80
82
84
86
88 90
92 94
96
34
36
38
40
42
44
46
48
50
52
54
56
58
60
62
64
Z
N
massfracRon
low
high
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HigherneutrondensiRes:n=1012cm-3
1.0e-2
1.0e-3
1.0e-4
1.0e-5
1.0e-6
1.0e-7
1.0e-8
1.0e-9
1.0e-10
1.0e-11
1.0e-12
1.0e-1t = 2.79e+07 sT = 1.5e+08 Krho = 1600 g/ccn = 1.0e+12 /cctau = 4.4 /mb
44 46 48 50
52
54 56
58
60
62 64
66 68
70 72
74 76 78
80
82
84
86
88
90
92
94
96
34
36
38
40
42
44
46
48
50
52
54
56
58
60
62
64
Z
N
massfracRon
low
high
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HigherneutrondensiRes:n=1014cm-3
1.0e-2
1.0e-3
1.0e-4
1.0e-5
1.0e-6
1.0e-7
1.0e-8
1.0e-9
1.0e-10
1.0e-11
1.0e-12
1.0e-1t = 3.06e+05 sT = 1.5e+08 Krho = 1600 g/ccn = 1.0e+14 /cctau = 4.8 /mb
44 46 48 50 52
54
56
58
60
62 64
66
68
70
72
74
76 78 80 82
84
86
88
90
92
94
96
34
36
38
40
42
44
46
48
50
52
54
56
58
60
62
64
Z
N
massfracRon
low
high
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HigherneutrondensiRes:n=1015cm-3
1.0e-2
1.0e-3
1.0e-4
1.0e-5
1.0e-6
1.0e-7
1.0e-8
1.0e-9
1.0e-10
1.0e-11
1.0e-12
1.0e-1t = 3.20e+04 sT = 1.5e+08 Krho = 1600 g/ccn = 1.0e+15 /cctau = 5.0 /mb
44 46 48 50 52
54
56
58
60
62
64
66
68
70 72
74
76
78
80 82
84
86
88 90
92 94
96
34
36
38
40
42
44
46
48
50
52
54
56
58
60
62
64
Z
N
massfracRon
low
high
Hampeletal.(2016)
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HigherneutrondensiRes:n=1015cm-3
1.0e-2
1.0e-3
1.0e-4
1.0e-5
1.0e-6
1.0e-7
1.0e-8
1.0e-9
1.0e-10
1.0e-11
1.0e-12
1.0e-1t = 3.20e+04 sT = 1.5e+08 Krho = 1600 g/ccn = 1.0e+15 /cctau = 5.0 /mb
44 46 48 50 52
54
56
58
60
62
64
66
68
70 72
74
76
78
80 82
84
86
88 90
92 94
96
34
36
38
40
42
44
46
48
50
52
54
56
58
60
62
64
Z
N
135I massfracRon
low
high
Hampeletal.(2016)
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iprocess:decays
1.0e-3
1.0e-4
1.0e-5
1.0e-6
1.0e-7
1.0e-8
1.0e-3
time(s) = 23815.4 T9 = 0.15 ⇢(g/cc) = 1600 flowmax = 2.47241e � 11
138Ba
138Cs
139Ba
131I
136Xe
131I
135Ba
134Ba
137Ba
136Ba
133I
132I
135I
134I
133Xe
132Xe
135Xe
134Xe
135Cs
133Cs
T1/2=6.6hrs
T1/2=2.3Myr
T1/2=9.15hrs
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Credit:HST/NASA/ESA
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iprocessabundancepagern
135I 135Ba
Hampeletal.(2016)
- Higher[Ba/Fe]veryligle138Ba
- Higher[Eu/Fe]- Same[Sr/Fe]
à higher[hs/ls]
also,[Ba/La]>0
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CEMP-istar:LP625-44
Hampeletal.(2016)
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CEMP-istars:Residuals
obs-m
od
Hampeletal.(2016)
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Theiprocess…• …isnotanewideaàCowan&Rose(1977)
• …needsasourceofneutrons:
Thei process…
• … isnotanewideaà Cowan&Rose(1977)
• … needsasourceofneutrons:
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Theiprocess…• …isnotanewideaàCowan&Rose(1977)
• …needsasourceofneutrons:
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Producingneutrons
12C 13C
(p,γ)
(β+)
(α,n)
13C(α,n)16O
• Take 12C and add protons:
12C(p, γ)13N(β+)13C
• Need high temperatures
• Proton abundance determines neutron density
• It’s a bit messy…
14C
13N 14N 15N
16O 14O 15O
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NeutronProfiles
Hampel+2018inprep.
H
H
H
H
H
H
H
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drgdfgdfgdfgdfg
NeutronProfiles:LessisMore!
ToohighprotonfracRons
àtooligleneutronexposure
H
H
H
H
H
H
H
H
H
H
H
H
H
H
Totalneutronexposure:
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CEMP-istar:LP625-44
Hampel+2018inprep.
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Conclusions
• CEMP-s/rstarsnotreadilyexplainedbyacombinaRonofs-andr-process
• Anintermediaten-captureprocessdoesamuchbegerjob! àCEMP-i
• NeedtoidenRfyapossiblesourceàprotoningesRonepisodes
– LowZAGBstars(e.g.Fujimotoetal.1990, seeSimonCampbell’stalk…)
– SuperAGBstars(Jonesetal.2016)– MassiveStars(seeBanerjee’stalk)– …