Theiprocessand

CEMPstars

Credit:HST/NASA/ESA

MelanieHampel

MonashUniversity

Withthanksto…

Credit:HST/NASA/ESA

RichardJ.Stancliffe

MariaLugaro

(Budapest)

BradleyMeyer

(Clemson)

CEMPstars:heavyelements

Lugaroetal.(2012),datafromMasseronetal.(2010)

highBa

highBaandEu

CEMPstars:heavyelements

Lugaroetal.(2012),datafromMasseronetal.(2010)

CEMP-s

CEMP-s/r,-r/s,-r+s,…,-i

FormaRonofCEMP-sstars

1 2

MSMS

Credit:CarloAbate

FormaRonofCEMP-sstars

Credit:CarloAbate

FormaRonofCEMP-sstars

1 2

white dwarfMS

CEMP star

Credit:CarloAbate

BinaryevoluRon+AGBnucleosynthesis?

Abateetal.(2015)

BinaryevoluRon+AGBnucleosynthesis?

Abateetal.(2015)

Atomicnumber

CEMP-s

BinaryevoluRon+AGBnucleosynthesis?

Abateetal.(2015)

BinaryevoluRon+AGBnucleosynthesis?

Abateetal.(2015)

Eu

[hs/ls]

heavyRE

BinaryevoluRon+AGBnucleosynthesis?

Abateetal.(2015)

Atomicnumber

CEMP-s

CEMP-s/r

R-processpre-enhancement?

Lugaroetal.(2012)

IniRal

r-process

enrichment:

atleast

[r/Fe]>1dex

R-processpre-enhancement?

Bisterzoetal.(2012)

IniRal

r-process

Enrichment:

[r/Fe]=1.5dex

R-processpre-enhancement?

Bisterzoetal.(2012)

IniRal

r-process

Enrichment:

[r/Fe]=1.5dex

[hs/ls]

heavyRE

R-processpre-enhancement?

Bisterzoetal.(2012)

IniRal

r-process

Enrichment:

[r/Fe]=1.5dex

HowdoCEM

P-s/rform?

??

R-processpre-enhancement?

Bisterzoetal.(2012)

IniRal

r-process

Enrichment:

[r/Fe]=1.5dex

Modifiednucleosynthesis?

Intermediateneutroncaptureprocess?

HowdoCEM

P-s/rform?

??

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

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

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

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

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

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)

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)

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

27

Credit:HST/NASA/ESA

iprocessabundancepagern

135I 135Ba

Hampeletal.(2016)

-  Higher[Ba/Fe]veryligle138Ba

-  Higher[Eu/Fe]-  Same[Sr/Fe]

à higher[hs/ls]

also,[Ba/La]>0

CEMP-istar:LP625-44

Hampeletal.(2016)

CEMP-istars:Residuals

obs-m

od

Hampeletal.(2016)

Theiprocess…•  …isnotanewideaàCowan&Rose(1977)

•  …needsasourceofneutrons:

Thei process…

• … isnotanewideaà Cowan&Rose(1977)

• … needsasourceofneutrons:

Theiprocess…•  …isnotanewideaàCowan&Rose(1977)

•  …needsasourceofneutrons:

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

NeutronProfiles

Hampel+2018inprep.

H

H

H

H

H

H

H

drgdfgdfgdfgdfg

NeutronProfiles:LessisMore!

ToohighprotonfracRons

àtooligleneutronexposure

H

H

H

H

H

H

H

H

H

H

H

H

H

H

Totalneutronexposure:

CEMP-istar:LP625-44

Hampel+2018inprep.

Conclusions

•  CEMP-s/rstarsnotreadilyexplainedbyacombinaRonofs-andr-process

•  Anintermediaten-captureprocessdoesamuchbegerjob! àCEMP-i

•  NeedtoidenRfyapossiblesourceàprotoningesRonepisodes

–  LowZAGBstars(e.g.Fujimotoetal.1990, seeSimonCampbell’stalk…)

–  SuperAGBstars(Jonesetal.2016)–  MassiveStars(seeBanerjee’stalk)–  …