Presented By: Paul Grenning


22 Φεβ 2014 (πριν από 7 χρόνια και 6 μήνες)

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Presented By: Paul

Deflagration is the ignition and combustion

Gasoline deflagrates when lit with a match

Detonation is the explosive force or shock compression

Dynamite detonates

Created by White Dwarf Stars

Final stage in a stars life

Super dense stars with the approximate energy of our
sun but the size of our earth.

The White Dwarf reaches the ignition temperature for
carbon fusion

White Dwarf merges with a second star it will exceed
the temperature required for nuclear fusion and
release enough energy to create the


Releases as much energy as our sun emits over its
entire life span

Cal Jordan

Robert Fisher

D. M.

A. C. Calder



D. Q. Lamb

J. W.

The primary theme of my
research is the fundamental
physics of turbulent flows,
and its application to a
variety of astrophysical

Interstellar Medium and
Star Formation

Computational Physics

Works at Dartmouth
college in MA in the
department of physics

My research interests lie
in refining stellar physics
via its application to
novel and dynamic
astrophysical systems

Visiting professor at
University Of Chicago

Assistant Professor at the
University Of Alabama in
the Department of
Physics and Astronomy

Their work is being done at the University of
Chicago's Center for Astrophysical
Thermonuclear Flashes

The scientists and engineers are using
Argonne’s super computer Blue Gene/P to
create the simulations

GCD (Gravitationally Confined Detonation)

To show the detonation conditions in a three
dimensional simulation in the GCD model is possible

In the past, extensive two
dimensional cylindrical
simulations have shown that detonation conditions are
robustly reached in the GCD model for a variety of
initial conditions

They believe that the conditions to create this type of
supernova can be better viewed in 3D rather than 2D


Supernovae are “Standard Candles”

These types of supernovae have revealed that the rate at
which the universe is expanding is accelerating

This has led to the discovery of “dark energy”

The biggest concern is that we do not know the causes of
these supernovae

Current models include

Pure Deflagration (PD)

Deflagration To Detonation Transition (DDT)


Detonation (PD)

Gravitationally Confined Detonation (GCD)

Only one to show the detonation arise naturally

Simulations use FLASH 3.0

An adaptive mesh hydrodynamics code for modeling
astrophysical thermonuclear flashes (such as
Supernovae, X
Ray Bursts, and classical Novae)

Uses the (advection
reaction)ADR flame

Numerically quieter

More stable

Exhibits smaller curvature effects

Leaves out nuclear burning outside the flame because
with it there would be too much overhead to show
such a robust simulation

Size of the flame bubble or thermonuclear flame
containing iron and other elements

Amount of iron and other elements


Offset of the flame bubble from the center

Calculations based on fluid dynamics

Use the Rayleigh
Taylor instability model

Instability of and interface between two fluids of
different densities which occurs when the lighter fluid
pushes the heavier fluid

Often creates a mushroom shape as the fluids merge and
pass through each other and become R
T unstable

Initially stationary thermonuclear flame at some measured offset
from the center

The flame produces hot ash

Velocity increases due to buoyancy and a mushroom like bubble

Velocity is much slower at the center due to the intense
gravitational pull

Velocity continues to increase as it moves to the surface of the
star and spreads rapidly over the surface.

Prior to hitting the surface, the bubble is carrying a range of
densities of iron and other elements

The ash breaks out of but remains gravitationally bound to the
surface of the star

Collides at a point on the opposite side of the star from the
breakout location and incinerates the star

The blue shows the approximate surface of the star and
the orange shows the interface between the star and
the hot ash produced by the flame.

In the animation, green represents the approximate
surface of the star and the colors mark regions of high
temperature in the billions of degrees Kelvin.

They ran 7 simulations for this paper

Different starting parameters

Conservative conditions necessary for detonation are
achieved in all cases

Ran more simulations with higher resolution and
farther offsets from the center and received similar

Computationally the results were similar with their
previous 2D simulation.

The result is based on their conclusion that buoyancy
driven nuclear burning is dependent on fluid
dynamics on large scales.

It is the kinetic energy originating from the breakout
of the bubble of hot ash imparted to the

surface layers of the star by the inwardly moving jet
generated by collision of the surface flows, that causes

material to achieve the conditions for

Explosions produced large amounts of Nickel and
small amounts of other elements

Different mass stars could explain the high levels of

The conditions are only for high
luminosity Type


Multiple ignitions near the center of the star

Produces a lower luminous explosion

Jordan, Cal., Fisher, Robert., and
, Dean, et al.
“Three Dimensional Simulations Of The Deflagration
Phase of the Gravitationally Confined Detonation
Model of Type

The Astrophysical

681.2, (July 2008): 1448

, B., Olson, K., and Ricker, P., et al. “FLASH: An
Adaptive Mesh Hydrodynamics Code for Modeling
Astrophysical Thermonuclear Flashes.”
Astrophysical Journal Supplement Series.

(November, 2000): 273