nucleosynthesis the making of the chemical elements · 2004-04-25 · roland diehl nucleosynthesis...

Roland Diehl<Nucleosynthesis_TUM_SS2004>

NucleosynthesisNucleosynthesisThe Making of the Chemical ElementsThe Making of the Chemical Elements

Advisor Seminar Physik-Departement TU MünchenDozenten der Astrophysik

SS 2004

Roland Diehl, Jochen Greiner, Günther Hasinger,Wolfgang Hillebrandt, Hans-Thomas Janka,

Ewald Müller, Volker Schönfelder


Overview: Themes and TopicsOverview: Themes and TopicsAstrophysical Environments of Nuclear Reactions

Nuclear Reactions of Thermalized ParticlesElementary Reaction TypesReaction Networks, Equilibria, Freeze-Out

Characteristic Cosmic Nucleosynthesis SitesThe Post-Big-Bang Area (BBN)Stellar Cores and Shells, Hydrostatic Nuclear BurningSNIa Explosions: Nuclear Statistical Equilibrium and Freeze-OutCore Collapse: Explosive Burning in Shock Regions, ν ProcessCompact Star Surfaces: Novae and X-Ray BurstsNeutron Capture Sites (cc-SNe, He Shells): r,s-ProcessesEnergetic Collisions in Interstellar Space, Near Compact Stars

Measurements of Isotopic AbundancesMeteorites, Stellar AtmospheresInterstellar GasHot Plasma, Radioactivities

Cycles of MatterChemical Evolution of Local Regions, Galaxies, Clusters


“Structures” of Matter at Different Scales“Structures” of Matter at Different Scales

Elementary Particles

Hadrons

Leptonsn,p

Isotopes

e-,ν

Atomic Nuclei

Molecules

Stars, Galaxies Dust…Solids…biological Bodies

Varieties of Appearances of Matter on Scales between Micro- and Macro-Cosmos:• “elementary” Building Blocks• “large-scale” Structures, Universes


Cosmic Element Formation StudiesCosmic Element Formation Studies

Goals:Understand the Physical Processes which Shaped the Pattern of Abundances in (different parts of) the UniverseIdentify & Model the Cosmic Sites of NucleosynthesisUnderstand Mixing Processes of Matter on Cosmic Scales

Standard Abundances

BiTh

PbPt

KrGe

Zn

Ni

Fe

CaArS

SiNe

CO

N

Ti

V

Sc

F

Be

LiB

H

Dy

Eu

BaSr

He

0

2

4

6

8

10

12

0 20 40 60 80 100

Element (Z)

Abu

ndan

ce (l

og N

, H=1

2)

R.Diehl_696_abundnc

fragile elements

α elements

...Fe group elements

(most tightly bound)

tighter-bound elements(closed shells)


Cosmic Nucleosynthesis: The IssuesCosmic Nucleosynthesis: The Issues

• Nuclear Structure, Nucleon InteractionsCoulomb Repulsion versus Strong InteractionCollective Interactions, Clusters

• Reaction Path far from StabilityNo Data from Nuclear-Physics ExperimentsLessons on Nuclear Physics from Astronomy

• Cosmic Environments of Nuclear ReactionsExplosive Heating & Burning Zone DilutionLongterm Evolutions in Stars (Convection) and Interstellar Medium (“chemical evolution”)

“Nuclear Astrophysics”


Nucleosynthesis: Understanding AbundancesNucleosynthesis: Understanding AbundancesObserved Abundances Show Characteristic Patterns

Abundances Vary Much for Light Elements uf to ~ Fe-Group,are ~Similar Order of Magnitude for Elements >65H and He are by far the Most Abundant ElementsLi, Be, B Fall in a Deep Minimum (9 Orders of Magnitude)Elements C....Ca Show Exponentially-Declining AbundancesThere is a Abundance Clear Peak Around FeThere are Two Local Peaks Around Ba and Pb

Nuclear Processes / Reactions “Connect” Neighbouring Isotopes (Reactions −> n, p, or α capture or stripping)

=>Big-Bang Nucleosynthesis Formed H and HeNuclear Equilibrium Burning Formed Fe ElementsAn “α-Process” Plays a Leading Role for Elements C...CaElements Heavier Than Fe Formed from Fe Elements

Standard Abundances

BiTh

PbPt

KrGe

Zn

Ni

Fe

CaArS

SiNe

CO

N

Ti

V

Sc

F

Be

LiB

H

Dy

Eu

BaSr

He

0

2

4

6

8

10

12

0 20 40 60 80 100

Element (Z)

Abu

ndan

ce (l

og N

, H=1

2)

R.Diehl_696_abundnc

fragile elements

α elements





Nucleosynthesis: “Processes”,“Categories”Nucleosynthesis: “Processes”,“Categories”Process Site Key Isotopes

H burning pp chains, CNO cycle all stars 4He; 13C 14N

He burning 3-α process most stars 12C 16O 20Ne 24Mg

α-process hot burning with excess α’s mass. stars, SNae 20Ne 24Mg 28Si 32S 36Ar 40Ca

Fe-group elements:e-process thermal equilibrium (NSE) SNae (thermonucl) Fe-group elements (~56)

n-rich heavy elements:s-process n capt. slower than β-decay He-burning stars elements >62 close to

valley of stabilityr-process n capt. faster than β-decay SNae (CC) elements >62, also further

from valley of stabilityspallation energetic heavy-ion collision ISM / cosmic rays 6Li 8,9Be 10,11B

p-rich isotopes:rp-process hot H burning novae p-rich elements <Fe groupp-process n depletion (‘γ-process’) ?? p-rich elements >62

‘normal’ nuclear reactions [(n,γ), (p,γ), (α,γ)...] stars, SNae in-between elementsν-process ν excitation of nuclei SNae (CC) various contributionsx-process unknown; make up for ?? (2H Li Be B)

BBN+Spallation definiency


the 3rd minute cataclysmic binaries

stellar evolution

SupernovaeAGB stars

Origin and fate of the elements in our universe

Nuclear Physics and Nuclear Physics and AstrophysicsAstrophysics

novaeWR stars


Cosmic Nucleosynthesis EnvironmentsCosmic Nucleosynthesis Environments

Nuclear Burning Requirements:• <σv> * Q ≥ Local Cooling Rate=>• Dense & Hot Environments

for a Stellar Mass Range of 1-30 Mo:

• Nuclear Burning in Stellar Cores and Shells (top)

• Nuclear Burning in Explosive Sites (bottom)

• Gamov Windows (righthand side)


Big Bang NucleosynthesisBig Bang Nucleosynthesis


Elementary NuclearElementary Nuclear--Reaction CyclesReaction Cycles

• H Burning: p-p Chains1H

1H

p2D

p

3He

3He

γ

1H

PP I4He

++++ ++

4He

++

7Beγ

γ

e-

PP II

7Lie+

ν ++ν

++

++p

4He

4He

1H8B

8Be

e+

ν

4He

PP III4He


Elementary Nuclear Burning CyclesElementary Nuclear Burning Cycles

• H Burning: CNO Cycle

p,γ p,α p,γ13C 14N 17O 18F

12C

13N

19F 20Ne

15O 17F

15N 16O 18O

p,γ

p,γ

e+ν

e+ν

p,γ

slow!

e+ν

p,α

p,α

p,αe+

ν

I II IIIslow!

p,γ

IV

p,γ p,γslow!!!

Net Burning towards 14N12C/13C ~4 (SAD:89)


Elementary NuclearElementary Nuclear--Burning CyclesBurning Cycles

• He Burning: 3α Cycle

4He + 4He 8Be

8Be + 4He 12C* 12C* 12C

Lifetime 8Be ~ 7 10-16 s8Be(α,γγ)12C through Excited Level at 278 keV+ (Salpeter, Hoyle)

ε ~ T840 −> He Flash

8Be + 4He7.366

12C 0+0.0

12C 2+4.43

12C 0+7.64

12C 3-9.64


Evolution ofEvolution of a a MassiveMassive StarStar

Gravity <-> Nuclear Energy

When Fuel Exhausted ->Contraction and Heating(Except if Degenerate)

-> … Fe Core


The advanced burning stagesare characterized by multiplephases of core and shell burning.The nature and number of suchphases varies with the massof the star.

Each shell burning episodeaffects the distribution of entropy inside the helium core and the final stateof the star (e.g., iron coremass) can be non-monotonicand, to some extent, chaotic.

Neutrino losses are higherand the central carbon abundancelower in stars of higher mass.


2626Al Nucleosynthesis: Example of a Cosmic Reaction Network, Al Nucleosynthesis: Example of a Cosmic Reaction Network, Common for IntermediateCommon for Intermediate--Mass IsotopesMass Isotopes

26Alm

28Si26Si

(p,γ)

(p,γ)(p,γ)

(p,γ)(p,γ)

(p,γ)

β+

β+(7.2s)

9.2 s β+

1.07 106 y

β+

(p,α)(p,α)

(n,p)

23Na

26Al

27Si

27Al

26Mg25Mg24Mg

25Al


Si Burning: QuasiSi Burning: Quasi--Statistical EquilibriumStatistical EquilibriumQSE Groups and their LinksQSE Groups and their Links

Hix & Thielemann, ApJ 1996

45Sc(p,γ)46Ti

Arrows = Relative Effectiveness of Reaction Link

• Reaction Links Depend on Most Critically on Ye


Massive Star Core StructureMassive Star Core Structure

1H, 4He

12C, 16O

4He

16O, 20Ne, 24Mg

28Si, 32S

16O, 24Mg, 28Si

Si−>Fe,Ni

O−>Si

Ne−>O

,Mg

C−>Ne,Mg

He−>C

,O

H−>He

9.9 9.5 8.9 8.7 8.3 7.0 log T

0.08

0

.02

0.15

0.0

5

0.1

0

.6

∆

m/M

envelope

envelope

corecore

(25 Mo)


ννν

νν

ννν

νν

νν

νν

ν

ν

ν

ν

ν

ν

ν

νν

ν

GravitationalCore Collapse

SupernovaShock Wave

Shock RegionExplosive Nucleosynthesis

Proto-Neutron StarNeutrino Heating

of Shock Region from Inside

Shell-StructuredEvolved Massive Star

Core CollapseCore CollapseSupernova Supernova ModelModel


Issues in CCIssues in CC--Supernova ModelsSupernova Models

ννν

νννν ν

ννννν νν

νν

νν

ν

ν

νν

ν

GravitationalCore Collapse

SupernovaShock Wave

Shock RegionExplosive Nucleosynthesis

Proto-Neutron StarNeutrino Heating

of Shock Region from Inside

Shell-StructuredEvolved Massive Star

• Explosion Mechanism = Competition Between Infall and Neutrino Heating• 3D-Effects Important for Energy Budget AND Nucleosynthesis• Location of Ejecta/Remnant Separation • 44Ti Produced at r < 103 km from α-rich Freeze-Out, => Unique Probe (+Ni Isotopes)


Accretion onto Compact ObjectsAccretion onto Compact ObjectsAngular Momentum of Matter Flow from Companion -> Accretion DiskAccretion Flow Dynamics -> Luminosity / Spectral “States”, InstabilitiesRadiation Sources:

– Accretion Disk– Corona– Compact-Star Surface

Scattering, Absorption


What Makes a Supernovae IaWhat Makes a Supernovae Ia

Close Binary System

White Dwarf Merger

BinaryMass Transfer

WD Giant

He Layer

He ShellFlash

WDat

MCh

CentralC Ignition

SN Ia

C/O Layer

SN IaSN IaModelsModels


How Does a SNIa Explode?How Does a SNIa Explode?

– C Ignition at MCh Limit (possibly many ignition points)

– Turbulent Flame Propagation– WD Expansion -> Flame Extinction

– Issues: Rapid Time Scales!» Nuclear Burning C+O->56Ni…» Expansion» Mixing


SupernovaeSupernovae

• Explosion of a Star• Nuclear Energy

ReleaseRadioactive By-Products of Explosive NucleosynthesisProgressive Transparency of Exploding Star

Thermonuclear Supernovae (Type Ia)Gravitational Collapse


Element Distribution in a Young SNRElement Distribution in a Young SNR

X-Ray Emission Lines– Element Abundance & Spatial

Distribution– Ionization Degree (Temperature &

Density)

Kepler, XMM/Newton:– SNR Cavity Hotter Inside– Fe and Si Distributions Similar– One-Sided CSM/ISM Interaction

Fe K image FeL contours 4-6 keV

Fe L Si K


Supernovae and Supernova RemnantsSupernovae and Supernova RemnantsCas A / XMM

Cas A 44Ti (τ~89y) / COMPTEL

• Prompt SN Light from Radioactivity• SN Debris Reflects Nucleosynthesis (and Collapsing-Star Structure)• Interaction of Blast Wave with ISM Results in Shocked Gas &

Recombination Radiation


Hot PlasmaHot Plasma

• T >> 6000KMatter Ionized: Ions and ElectronsProcesses:

– Coulomb Scatterings– Bremsstrahlung / Free-Free Radiation– Recombinations / Ionizations– Comptonization / Compton Scattering

Thermal and Non-Thermal Particle Populations (->Radiation Components)

ROSAT AAT

Chandra


Accreting Neutron Stars: X-ray bursters

Neutron star(H and He burninto heavier elements)

Companion star(H + He envelope)

Accretion disk(H and He fallonto neutron star)

500 600 700 800 900Time (s)

0

2000

4000

6000

X-ra

y flu

x (c

ts/s

)

X-ray burst

10-100 s

18 18.5time (days)

(4U 1735-44)

4.8 h

“Superburst”


rprp--Process: Impulsive HProcess: Impulsive H--BurningBurning• X-ray Burst Sources:

Nuclear Flash of Accreted H Surface Layer of Neutron Star

• Nuclear Energy < Accretion Luminosity

• Type-I X-ray BurstRecurrence Periods ~h...d (Accretion of <10-8 Mo yr-1)

• rapid p Captures and β-Decays Dominate Nuclear Reactions(hot CNO, ...)

• rp Process Termination through SnSbTe Cycle

• Cosmic Source of Specific p-Isotopes (92,94Mo, 96,98Ru)

• Ref.: Bildsten 2000, Schatz et al. 2001


Atomic Nuclei: Stable and RadioactiveAtomic Nuclei: Stable and Radioactive

• Stable Isotopes• n and p Evaporization Limits (‘drip lines’)• Regions of α, β+, β- Decaying Isotopes

30

40

50

60

70

60 70 80 90 100

Neutronenanzahl

Prot

onen

-Anz

ahl

s-only

r-only

N=Z

r-Prozess Pfad

-Zerfälle

s-Prozess Pfad

Anzahl Neutronen

Anz

ahl P

roto

nen

stabile Isotope

β- -Zerfalls-instabil

β+ -Zerfalls-instabil


ss--ProcessProcess• Successive n Captures, Allowing Time for In-Between β Decays • n Densities ~ 108 cm-3

• Populates Isotopes on the n-Rich Side Along the Valley of Stability• Isotopes with a Stable n-richer Isobar are ‘s-Process-Only’-Produced (shielded)• Likely Site:

Stellar Hydrostatic Burning (Shellsin Giant Stages)

n Capture

50

55

60

65

65 70 75 80 85 90

No. of Neutrons

No.

of P

roto

ns

rod696abundnc

s-only

r-onlys-process path

134Xe

134Ba

abundance distribution with A: narrow s-process peak, broad r-process bump


Production of Elements Beyond the Fe Peak:Production of Elements Beyond the Fe Peak:rr--Process and sProcess and s--ProcessProcess

• Seed Nuclei (~ Fe-Group Elements) Capture Neutrons• β Decays Establish Final Abundances

n capture faster than β-decay −> r-processn capture slower than β-decay −> s-process

30

40

50

60

70

60 70 80 90 100

No. of Neutrons

No.

of

Prot

ons

s-only

r-only

N=Z

r-process pathβ

-decays

s-process path


rr--ProcessProcess• “Waiting-Point” Approximation:

r-Process Path = Connection of Isotopes with Identical Neutron Separation Energy Sn

Constant Neutron Flux and Temperature over Exposure TimeInstantaneous Freeze-OutSubsequent β-Decays

• Phenomena & ResultsAbundance Peaks at A=80,130,195r-Process Path ~15-35 Units from Valley of StabilitySn ~ 2-4 MeVnn ~ 1020-1024 cm-3, T ~ 1.4 109Kτ ~ 10-4...2 sec

• Unknowns: Astrophysical Site & ParametersNuclear Structure far off Stability

• Two Independent r-Process Sites?• Likely Sites:

ν Wind from PNS in collapsing Fe Core of cc-SN Explosive He Shell Nucleosynthesis (13C,20Ne)

• ‘Shell-Quenching’ Models for Nucleus May Be Favored

Neutron Separation Energy Contours (Example, Freiburghaus et al. 1999)

Abundance Comparisons(Pfeiffer et al. 1997)


Elemental Abundances / MetalElemental Abundances / Metal--Poor StarsPoor Stars

Observations of Elemental Absorption Lines in Stellar SpectraHalo Stars:

– Metal-Poor– Metals from Single Nucleosynthesis Event Nearby?

Study Single-Event Synthesis of Elements > Fe (r,s-Process)

Sneden et al., ApJ 2000


HighHigh--Energy Interactions of Cosmic MatterEnergy Interactions of Cosmic Matter

• Relativistic Particles Interact with:Electromagnetic Fields

Curvature RadiationSynchrotron RadiationBremsstrahlungPair Creation

Particles, AtomsNuclear ExcitationSpallation


neutrons

protons

rp processrp process

r processr process

Mass knownHalf-life knownnothing known

s processs process

stellar burningstellar burning

Big BangBig Bang

p processp process

SupernovaeSupernovae

Cosmic RaysCosmic RaysH(1)

Fe (26)

Sn (50)

Pb (82)


Astronomical Instruments: GroundAstronomical Instruments: Ground--BasedBased

NTT

EffelsbergArecibo

VLTHEGRA


Astronomical Instruments: HE Space MissionsAstronomical Instruments: HE Space Missions

ROSAT

CGRO

INTEGRAL SWIFT


Cosmic Objects: Which Isotope Composition, Why?Cosmic Objects: Which Isotope Composition, Why?

• Galaxies• Stars• Interstellar

Gas


MassiveMassive--Star / ISM InteractionsStar / ISM Interactions

100 95 90 85 80 75 70 65lII [deg]

−10

−5

0

5

10

15

20

bII [deg

]

Maximum Entropy 1.8 MeV Map

100 95 90 85 80 75 70 65lII [deg]

−10

−5

0

5

10

15

20

bII [deg

]

1.8 MeV Emission Model

OB1

OB2OB3

OB7OB8

OB9

OB4

• Massive Stars Often Form in Groups• Massive-Star Winds and SNae

Determine the ISM Morphology• Massive-Stars’ Metal-Enrichment of ISM

Determines Chemical Evolution

• Evolution Time Scale of Stellar Groups: ~ 10-100 Myr

• Evolution Time Scale of Massive Stars: ~0.1-10 Myr

• Cosmic-Ray ‘Propagation Age’ ~10 Myr

• Evolution of Stellar Populations• Evolution of Diffuse Emission • Issues in Massive-Star/ISM Interactions

ISM/Shock InteractionsHot-Bubble EvolutionMatter RecyclingStar Formation HistoryISM Morphology


The Cosmic Cycling of MatterThe Cosmic Cycling of Matter

dense molecular

cloudscondensation

star formation (~3%)

mixing

SN explosion

106-1010 y

108 yM~104...6 Mo

SNIa

~90%

infall

winds

stars

M > 0.08 Mo

stars

Galactic

halo

… galaxy collisions…

interstellarmedium

dustdust

SNR's &hot

bubblescompact remnant

(WD, NS,BH)

102-106y


Abundances in Intergalactic GasAbundances in Intergalactic Gas

• X-Ray Spectroscopy (XMM/Newton, ZEUS)Study Composition of Inter-Cluster Gas

– Large-Scale Transport of Nucleosynthesis Products– Nucleosynthesis Across the Universe

Chandra 3C295


Nucleosynthesis: Understanding AbundancesNucleosynthesis: Understanding AbundancesObserved Abundances Show Characteristic Patterns

Abundances Vary Much for Light Elements uf to ~ Fe-Group,are ~Similar Order of Magnitude for Elements >65H and He are by far the Most Abundant ElementsLi, Be, B Fall in a Deep Minimum (9 Orders of Magnitude)Elements C....Ca Show Exponentially-Declining AbundancesThere is a Abundance Clear Peak Around FeThere are Two Local Peaks Around Ba and Pb

Nuclear Processes / Reactions “Connect” Neighbouring Isotopes (Reactions −> n, p, or α capture or stripping)

=>Big-Bang Nucleosynthesis Formed H and HeNuclear Equilibrium Burning Formed Fe ElementsAn “α-Process” Plays a Leading Role for Elements C...CaElements Heavier Than Fe Formed from Fe Elements

Standard Abundances

BiTh

PbPt

KrGe

Zn

Ni

Fe

CaArS

SiNe

CO

N

Ti

V

Sc

F

Be

LiB

H

Dy

Eu

BaSr

He

0

2

4

6

8

10

12

0 20 40 60 80 100

Element (Z)

Abu

ndan

ce (l

og N

, H=1

2)

R.Diehl_696_abundnc

fragile elements

α elements




nucleosynthesis the making of the chemical elements · 2004-04-25 · roland diehl nucleosynthesis...

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