1. Gas and Dust Layers from Cassiopeia A’s Explosive Nucleosynthesis
L. Rudnick, University of Minnesota
OMEG07

2. The work of many experts…
SPITZER
T. DeLaney, MIT
J. Ennis, U Mn
T. Kozasa, Hokkaido
H. Morgan, Cardiff
W. Reach, Spitzer
J. Rho, Spitzer
J.D. Smith, U. Ohio
RADIO, X-RAY, OPTICAL
R. Petre, U. Hwang, GSFC
R. Fesen (Dartmouth)
J. Bowden (Colorado Coll.)
N. Kassim (Naval RL)
Funding: NASA (Chandra/HST/Spitzer) and NSF (radio)

3. Key Questions What is the shape of the explosion?
What is the fate of the nucleosynthesis layers?
What is the mass and composition of new dust?
What is the future?

4. Messages to take home •
Until now, the ONLY ejecta which have been seen in Cas A (optical, IR, X-ray, radio) are those that
have just crossed the reverse shock
The explosion of the inner layers was flattened.
with multiple “jets”  different nucleosynthesis layers are now visible in each direction.
Dust becomes visible at the reverse shock, with different compositions from different layers
The currently visible dust mass is
MO, with even more in the interior?
Add pictures •

5. Outer and reverse shocks
EXPLOSION STRUCTURE
Outer and reverse shocks

6. Multiple temperature overlapping plasmas
EXPLOSION STRUCTURE
Multiple temperature overlapping plasmas
104K
relativistic
107K
102K

7. EXPLOSION STRUCTURE
Proper Motions
optical
X-ray (~radio)

8. A paradox – optical, X-ray, radio
EXPLOSION STRUCTURE
A paradox – optical, X-ray, radio

9. New view of the explosion
EXPLOSION STRUCTURE
New view of the explosion

10. The motion of material is different than the motion of the shock –
EXPLOSION STRUCTURE
The motion of material is different
than the motion of the shock –
Ejecta become visible as they encounter the reverse shock
Milliseconds seconds
into the explosion

11. EXPLOSION STRUCTURE
Doppler 3D structure
Show movies
Argon
Silicon

12. The Explosion in 3-D

13. The explosion of the inner layers has a flattened (pancake) structure
EXPLOSION STRUCTURE
The explosion of the outer layers was spherical, setting up forward and reverse shocks.
The explosion of the inner layers has a flattened (pancake) structure
“Fingers” or jets of material protrude in the plane separating the layers

14. NUCLEOSYNTHESIS LAYERS
As the jets cross the reverse shock and become visible, the nucleosynthesis layers remain intact

15. Different layers in the gas
NUCLEOSYNTHESIS LAYERS
Different layers in the gas
Ne-rich
layers
OIV
X-ray Si GAP

16. Different layers in the dust

17. Dust – compositions Circumstellar Small carbon grains, PAH?
DUST TYPE & MASS
Circumstellar
Small carbon
grains, PAH?
Deep layers
Si, Ar, S +
dust: SiO2, FeO,
MgSiO3
Note – several different types of continuum with weak or no silicates
Intermediate layers:
Ne, O + dust: Al2O3

18. Dust Composition - closer look
DUST TYPE & MASS
Dust Composition - closer look
Deep, O-burning
Intermed., C-burning
Al2O3
proto-silicate peak
Show spectra here

19. Dust Mass Distributions
DUST TYPE & MASS
Dust Mass Distributions
Deep, O-burning
Intermed., C-burning

20. Ejecta dust mass…total visible…
DUST TYPE & MASS
Ejecta dust mass…total visible…
0.02 < Mdust/MO < 0.054 .
CSM
Silicates
C-products
Expectations for production,
e.g., Nozawa et al up to ~1 MO
Low end of requirement for
dust seen at high z,
BUT, destruction should also be
very important!
Uncertainties from thickness of H envelope, CSM, amount of destruction

21. Very cold ejecta dust? or ISM from foreground CO clouds?
Uncertainties
DUST TYPE & MASS
How to fit 70m?
70m
21m
Very cold ejecta dust? or ISM from foreground CO clouds?
850m
13CO
70 clearly connected with 21, therefore ejecta – but fitting quite uncertain because requires cooler components, e.g., 50??, that make only smaller contribution
How much dust has not yet reached reverse shock?

22. Is there more dust to come?
FUTURE
Is there more dust to come?
Si XIV
Si II

23. Messages to take home
Until now, the ONLY ejecta which have been seen in Cas A (optical, IR, X-ray, radio) are those that
have just crossed the reverse shock
The explosion of the inner layers was flattened.
with multiple “jets”  different nucleosynthesis layers are now visible in each direction.
Dust becomes visible at the reverse shock, with different compositions from different layers
The currently visible dust mass is
MO, how much more in the interior?
Add pictures .