Test of stellar hydrodynamics predictions

NIF Tests of Stellar
Hydrodynamics Predictions
Tomek Plewa
Florida State University
Paul Drake, Artur Gawryszczak, Mike Grosskopf,
Eric Harding, Konstantinos Kifonidis,
Carolyn Kuranz, Aaron Miles, Andrzej Odrzywolek,
Hye-Sook Park, Bruce Remington

Outline
Supernovae
Computations and Astrophysics
HED Supernova Applications
Nike: thermonuclear SNe: mergers, shear, and turbulence
Omega: thermonuclear SNe: surprises on small scales
NIF: core-collapse SNe: Diverging SN RT (SN 1987A)
Discussion
i
April 26, 2011
2

Our Stellar Neighbours
Type II
Massive
Single
H-rich
Type Ia
Medium
mass
Binary
H/He-free
White Dwarfs
m < 1.4 Msun
Brown Dwarfs
m > 0.075075 Msun
April 26, 2011
3

Computational Astrophysics
observation
telescopes, satellites
CCDs, spectrographs
data analysis
observations, errors
theory
model refinement
motivate observing campaign
physical interpretation
mathematical model
numerical representation
simulation
model observables
model errors (convergence)
computations
April 26, 2011
4

Computational Astrophysics
A coupled set of PDEs and ODEs.
t
U F
2
4G
U
SU
PDEs across the whole spectrum from elliptic (self-gravity) and
parabolic problems (elemental diffusion) to hyperbolic systems
(hydrodynamics).
ODEs frequently stiff (nuclear reaction networks). The whole
system might be stiff even if the individual components are not.
One-dimensional problems of limited importance. Most interest
in large-scale multidimensional applications.
Temporal and spatial scales may vary vastly. Need methods
adaptive in space and time. Andsubgrid scale models.
Occasional flashy one-time hero-like demonstration runs,
mostly beneficial to sponsors and/or public.
Requires ”unlimited” computing power.
April 26, 2011
5

Verification, Validation, and Uncertainty
Notion of validation is present in computational
astrophysics
Verification uses analytic solutions; (self-)convergence
studies done almost exclusively in spatial domain
Code-to-code comparisons since late1980s; several projects
later; growing in popularity (self-confidence builders)
Validation largely limited to “application to experiment”
Low relevance is one major factor/relatively immature
Historically more emphasis on observational rather than
laboratory experiments
UQ is mostly absent due to high “added” cost (discovery is
valued much higher)
April 26, 2011
6

Thermonuclear Supernovae
Type Ia
Medium
mass
Binary
H/He-free
April 26, 2011
7

SN Ia: Double Degenerates
Double Degenerate (WD+WD) is alternative Type Ia SN
formation channel to Single Degenerate (MS+WD)
Possibly dominant in early type galaxies (Gilfanov & Bogdan
2010), maybe overall…
Theoretical studies
Formation: Iben & Tutukov (1984)
Rates: Han & Podsiadlowski (1994), Scannapieco & Bildsten (2005),
Mannucci et al. (2005), Greggio (2005), Pritchet et al. (2008), Ruiter et
al. (2009), Schawinski (2009)
Merger models:
1D: Nomoto & Iben (1985), Nomoto et al. (1991, AIC), Saio et al. (1989),
Clayton et al. (2007, R CrB)
2D: Mochkovitch & Livio (1989, 1990)
3D:
Unequal masses: Benz et al., Piersanti et al., Guerrero et al.,
Segretain et al., Yoon et al., Loren-Aguilar et al.
Equal masses: Pakmor et al. (2010, prompt ignition!!)
April 26, 2011
8

SN Ia: Double Degenerates
Products of close binary stellar evolution
Possibly similar intermediate stellar masses
Two white dwarfs are end products of stellar evolution
Rodriguez et al. (2007)
April 26, 2011
9

Shear, Turbulence, Combustion
64 km
April 26, 2011
Work done in collaboration with A. Gawryszczak (Copernicus Center, Warsaw). Computing cycles: DOE NERSC.
10

Quest for Thermonuclear Ignition
April 26, 2011
Work done in collaboration with A. Gawryszczak (Copernicus Center, Warsaw). Computing cycles: DOE NERSC.
11

Supernovae Do Not Love Us Back!
• Theory ultimately insufficient…
• Computations not terribly successful…
• Experiments…? :-\
April 26, 2011
12

HED Laboratory Astrophysics
High Energy Density: p > 1 Mbar, energies > 10 11 J/m 3
or > 10 12 erg/cm 3 , temperatures > 5x10 6 K or > 400 eV
ICF
radhydro
HEDLA
April 26, 2011
Davidson et al. (2004)
13

Supersonic Shear in HED Experiments
Experimental setup (NIKE laser)
Low-density material with machined sinusoidal perturbation
High-velocity laser-driven flow
Harding et al. (2010)
Anticipated behavior
Aluminum flows horizontally and drives a weak shock into the foam
Horizontal shear between aluminum and shocked foam induces Kelvin-
Helmholtz instability
The flow near the interface is supersonic
April 26, 2011
14

Supersonic Shear in HED Experiments
Observed behavior
Harding et al. (2010)
April 26, 2011
15

Supersonic Shear in HED Experiments
Observed detail; estimated Ma ~ 2.8
Simulation results; estimated Ma ~ 6-8
Possible explanations
Lateral flow expansion neglected in hydro (2D) models
EOS effects
April 26, 2011
16

SN Ia: Single Degenerates
Products of close binary stellar evolution
Unequal initial masses => different evolutionary timescales
Primary evolves faster and becomes a white dwarf while the
secondary becomes a (slightly) evolved non-degenerate
companion
NASA/D. Berry
April 26, 2011
17

Single-Point Central Ignition
Linde & Plewa (2004)
April 26, 2011
18

RT-Unstable Supernova Flame
Zhang et al. (2007)
April 26, 2011
19

Surprises from HED RT Experiments
Smooth spike morphology
Spike mass extensions
Density profile analysis
Kuranz et al. (2009)
April 26, 2011
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Successful Gedanke Experiments
• Smooth spike morphology
• Thermal conduction?
Harden &
Plewa (2009)
• Spike mass extensions
• Not seen in the above model with thermal conduction, nor in pure
hydro models
April 26, 2011
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Gedanke Experiments
• Smooth spike morphology
• Thermal conduction?
Success!
Harden &
Plewa (2009)
• Spike mass extensions
• Not seen in the above model with thermal conduction, nor in pure
hydro models
Failure!
April 26, 2011
22

Discovery Science, At Last?
• In-situ generation of magnetic fields via the Biermann battery
mechanism (Kuranz et al. 2010)
- cross of electron density and temperature gradients
B
t
ck
e
B
T
e
ln n
- usually neglected term in the induction equation
- induced magnetic field => extra pressure
e
• Consequences for supernovae
• Magnetic pressure comparable to the thermal pressure at the
thermonuclear deflagration front => possibly critical for SN Ia
• Estimated negligible in core-collapse
Fryxell et al. (2010)
April 26, 2011
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Magnetized (Large Scale) RT Model
negligible field:
beta=250,000
modest field:
beta=2,500
See also early work by Jun, Norman, & Stone (1995).
April 26, 2011
24

Core-Collapse Collapse Supernovae
Type II
Massive
Single
H-rich
April 26, 2011
25

Supernovae From Single Stars
April 26, 2011
26

Obs. #1: SN 1987A ejecta tomography
Hanuschik et al. (1991)
April 26, 2011
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Obs. #2: SN 1987A “mystery spot”
Niesenson et al. (1987) Niesenson & Papaliolios (1999)
April 26, 2011
Wang et al. (2002)
28

Core-Collapse Collapse SN Explosion Drive
Massive stars
Gravity bombs
Energy extracted by neutrinos
Accretion shock originally too weak
Revived by neutrino heating of the post-shock matter
April 26, 2011
29

Standing Accretion Shock Instability
Janka et al. (2006)
April 26, 2011
30

SASI in 3D
Princeton
LANL
ORNL
MPA
FSU
April 26, 2011
31

Gedanke Experiment!
Can We Test It?
Ohnishi et al. (2008)
• NIF design work w/Tim Handy at FSU in progress
possible NIF design
April 26, 2011
32

Complex Post-Explosion SN Dynamics
Triple
Kelvin-Helmholtz
Leading Shock Front
Point
Triple
point
Rayleigh-Taylor
Rayleigh-Taylor
Reverse Shock
April 26, 2011
Kelvin-Helmholtz
Fallback
Reverse Shock
33

Origins of the Mixing: SN RT
• Time-dependent deceleration of dense layers due to unsteady
supernova shock motion though the progenitor envelope
April 26, 2011
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Post-Explosion: Shocking the Envelope
April 26, 2011
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Memory of the Explosion
Angular evolution of the ejecta mass distribution
expansion
toward
poles
SASI imprint
April 26, 2011
36

56 Ni. How Much? How Fast?
Following SN 1987A observations, 56 Ni distribution
evolution is one of the primary model evaluation criteria
April 26, 2011
37

Toward Observables: Young ccSNR
April 26, 2011
38

HED Tests of ccSN RT Mixing
• Motivated by SN 1987A
• Theoretical foundations provided by HED scaling laws
(D. Rytuov and collaborators)…
April 26, 2011
39

HED SN Experiment Scaling
Formal challenge
(no tough love)
April 26, 2011
Drake et al. (2002)
40

HED Tests of ccSN RT Mixing
• Motivated by SN 1987A
• Theoretical foundations provided by HED scaling laws
(D. Rytuov and collaborators)
• Most work devoted to planar, two-layer targets (classic
RT configuration)
• But SN are largely spherical… => spherical targets and
diverging flow configurations
• Much more mass involved than in the planar case, thus
requiring much more energy to drive
• Early attempts (on Omega) unsuccessful (shell
breakup) => NIF!
April 26, 2011
41

Diverging Supernova Explosion
Experiments on NIF
• NIF Facility Time (Rosner’s Committee)
• Purpose: This experiment attempts to observe e extensive e Rayleigh-
Taylor driven mixing in the exploding massive stars. Data will give
physics insights of inter-shell penetration outwards to surface via
turbulent mixing, shell breakouts, growth of secondary instabilities,
vorticity-enhanced mixing.
• 15 shots starting in AY 2012
• Natural continuation of the previous work on Omega
• NIF is unique facility enabling studies with spherical targets
(diverging i flow geometry)
• New diagnostics (IXTS, Dante, proton radiography…) in addition to
standard diagnostics (x-ray radiography)
April 26, 2011
42

NIF DSNRT Diagnostics
April 26, 2011
43

NIF DSNRT Target
Ag wedge pressure
retainer
0.1g/cc CRF foam
0.1g/cc CRF foam
1 g/cc CH
CHI tracker,
200 um wide
small section
in the middle
0.0 6.528 mm radius
0.728 1.928
Cu or Ti
Ripple interface
0.928
for some targets
Ripple interface =xx m, =yy
20 um
for some targets
mm
thick CH
=70-100 m,
ablator
=2.5-3.5 m
inside
April 26, 2011
44

NIF DSNRT Design
Grosskopf et al. (2011)
April 26, 2011
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Summary
SN Ia: Binary white dwarf mergers: shear and turbulence
Unequal masses: no evidence for prompt ignition
Equal masses: no evidence for prompt ignition
Expect central ignitions with fast rotating envelopes
Likely different from typical models with smooth rotation
Perhaps similar to Yoon & Langer structure
Shear/KHI HED studied and analyzed; HED turbulence experiment concept developed
SN Ia: In-situ generated magnetic fields for Type Ia deflagrations
Identified as a possible new physics in HED RTI experiments
For supernova conditions, reduced turbulence near the flame
Smoother flame surface
Lower effective flame speed, large scales more important
Flame remains RT-driven and mushroom-like in appearance
SN II: Core-collapse
Exploring possible SASI experimental designs
SASI asymmetries may suffice to explain SN 1987A and alikes
Crab-like spongy morphologies for young ccSNR
Diverging SNRT to be executed on NIF!
April 26, 2011
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April 26, 2011
Questions and Discussion
47