All Figures

Figure 1: Ignition lines giving a necessary condition for a thermal fluctuation to grow and develop a carbon runaway in a localized region. Horizontal axis is the size of the fluctuation,  at the center of the bubble (see Eq. (1)). Vertical axis is the radius encompassed by the fluctuation and each one of the five lines represent a particular background temperature . The area above the corresponding line gives the locus of successful ignitions.

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In the text

	Figure 2: Evolution of the thermal profile within the bubble from the initial fluctuation until the carbon runaway. It takes less than 3 s for the center of the bubble to reach 109 K. During this time the bubble radius increases by a factor of two and the background temperature rises owing to the release of nuclear energy.
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In the text

	Figure 3: Evolution of the distribution function of radius of the igniting bubbles as a function of time since ignition, for R0 = 107 cm. The lines correspond to times t = 0.1, 0.3, 1, and 3 s.
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In the text

	Figure 4: Distribution function of the radii of the igniting bubbles at a time t = 0.1 s, for different values of R0: 104 cm ( solid line), 106 cm ( dotted line), and 107 cm ( dashed line). Note the linear scaling of the vertical axis in this figure, in contrast with the logarithmic scaling of the previous one.
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In the text

	Figure 5: Snapshots of the temperature distribution in a meridian plane of model B30U at times from 0 to 1.3 s, in steps of 0.15 s. The temperature scale is shown at the bottom left of the image, while the length scale is shown at the top left of each snapshot (the length of the vertical bar is equivalent to 200 km).
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In the text

	Figure 6: Radii of the centers of mass of the 30 bubbles of model B30U. The filled symbols over a line mark the time at which interaction with any other bubble first occurs.
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In the text

	Figure 7: Radial velocity of the bubbles as a function of the radii of their centers of mass, for model B30U.
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In the text

	Figure 8: Masses of the bubbles in model B30U.
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In the text

	Figure 9: Fuel consumption rate of the bubbles, for model B30U.
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In the text

	Figure 10: Temporal evolution of temperature ( top graph), and burnt mass fraction ( bottom graph), for model B30U. The times shown are: 0 (solid line), 0.2, (dotted line), 0.4 (short-dashed line), 0.6 (long-dashed line), 0.8 (dot short-dashed line), and 1.0 s (dot long-dahsed line). The plotted quantities have been averaged over spherical shells.
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In the text

	Figure 11: The time evolution of the ratio of the local flame velocity to the non-linear Rayleigh-Taylor velocity for each bubble of model B30U.
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In the text

	Figure 12: Snapshots of the temperature distribution in a meridian plane of model B07U at times from 0 to 1.05 s, in steps of 0.13 s. The temperature scale is shown at the bottom left of the image, while the length scale is shown at the top left of each snapshot (the length of the vertical bar is equivalent to 200 km).
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In the text

	Figure 13: Snapshots of the temperature distribution in a meridian plane of model B90R at times from 0 to 1.10 s, in steps of 0.14 s. The temperature scale is shown at the bottom left of the image and the length scale is shown at the top left of each snapshot (the length of the vertical bar is equivalent to 200 km).
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In the text

	Figure 14: Fuel consumption rate of the bubbles for model B07U.
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In the text

	Figure 15: Fuel consumption rate of the bubbles, for model B90R.
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In the text

	Figure 16: Nuclear energy generation rate as a function of time. Solid line: model B30U, dashed line: model B90R, dotted line: model B7U.
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In the text

	Figure 17: Total fuel consumption rate as a function of density. Solid line: model B30U, dashed line: model B90R, dotted line: model B7U.
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In the text

	Figure 18: Final distribution of elements in velocity space. Top: model B30U, bottom: model B90R. The composition corresponds to the final products after radioactive disintegrations.
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In the text

	Figure 19: Distribution of iron as a function of the components of the velocity, model B30U.
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In the text

	Figure 20: Final (at  s) chemical composition mapped onto a meridional plane, for models B30U ( top row) and B90R ( bottom row).
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In the text

	Figure 21: Mean of the fractional change in particles velocity with respect to its final velocity. A 5% difference is attained at 16 s, and a 1% difference at 27 s.
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In the text

	Figure 22: Radius of each SPH particle at  s vs. final radius, for model B30U.
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In the text

	Figure 23: Velocity of each SPH particle at  s vs. final radius, for model B30U.
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In the text

	Figure 24: Radial velocity of the bubbles relative to their environment, for model B30U.
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In the text

	Figure 25: Column density of 56Ni above the photosphere and contours of constant normal velocity at the photosphere, both for model B30U 15 days after the explosion.
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In the text

Figure A.1: Radius of transition from spontaneous combustion to conductive flame as a function of the characteristic lengthscale of the thermal profile of the bubbles.


In the text

Figure A.2: Snapshots of the temperature distribution in a meridian plane of model B30U at times from 0 to 1.3 s, in steps of 0.15 s. The temperature scale is shown at the bottom left of the image, while the length scale is shown at the top left of each snapshot (the length of the vertical bar is equivalent to 200 km).


In the text

Figure A.3: Snapshots of the temperature distribution in a meridian plane of model B07U at times from 0 to 1.05 s, in steps of 0.13 s. The temperature scale is shown at the bottom left of the image, while the length scale is shown at the top left of each snapshot (the length of the vertical bar is equivalent to 200 km).


In the text

Figure A.4: Snapshots of the temperature distribution in a meridian plane of model B90R at times from 0 to 1.10 s, in steps of 0.14 s. The temperature scale is shown at the bottom left of the image, while the length scale is shown at the top left of each snapshot (the length of the vertical bar is equivalent to 200 km).


In the text

Figure A.5: Final (at  s) chemical composition mapped onto a meridional plane, for models B30U ( top row) and B90R ( bottom row).


In the text

Figure A.6: Column density of 56Ni above the photosphere and contours of constant normal velocity at the photosphere, both for model B30U 15 days after the explosion.


In the text