Now Playing: Core Collapse in 3D

Rereleasing old movies converted to 3D may be all the rage these days, but here’s a star-studded 3D update worth waiting for: the core collapse of a supernova.

This image from the team's simulation depicts the core (roughly the inner 100 km) collapsing in the beginning stages of a Type II supernova. The infalling matter is bubbling from the hot blast of neutrinos, pushing against the shock wave of collapsing matter (the outer blue membrane). The just-formed neutron star is visible in the center as the small blue sphere.
Elena Erastova and Markus Rampp, RZG
Despite the mainstream recognition of these explosive deaths of massive stars, we still don’t understand what triggers them. The conventional wisdom is that when the core collapses to form a neutron star, the recombining protons and electrons release a tremendous amount of energy in the form of neutrinos, creating a shock wave that travels out through the layers of the star. When it reaches the surface — well, not even Michael Bay’s filmed an explosion that large.

But there’s a problem: Theorists just can’t get their model supernovae to explode. In simulations, the shock wave stalls out and never reaches the surface. Until recently, however, these intensive calculations have been made in only one or two dimensions.

This week, a team of researchers at the Max Planck Institute for Astrophysics announced a 3D simulation of the initial stage of a supernova — the core collapse that gives birth to the neutron star. In a video of their simulation, released Tuesday, the shock undergoes a spectacular sloshing behavior called a “standing accretion shock instability.” (Don’t go looking for your 3D anaglyph glasses though — the video itself is traditional 2D.) In future work, they hope to address whether this could help propel the shock through the star.

Now, we decided to take a somewhat unorthodox approach befitting a summer blockbuster release. We’ve added annotations to explain what’s happening, and our intern wrote some…music.

You’ll see what we mean.

For more information, check out the press release and the videos in Figure 3 that demonstrate how the chaotic behavior of the shock wave can be reproduced with water, a table, and a pipe.

References

Hanke F., Müller B., Wongwathanarat A., Marek A., Janka H.-Th., “SASI Activity in Three-Dimensional Neutrino-Hydrodynamics Simulations of Supernova Cores”, Astrophysical Journal 770, 66 (2013)
http://arxiv.org/abs/1303.6269

Foglizzo T., Masset F., Guilet J., Durand G., “Shallow Water Analogue of the Standing Accretion Shock Instability: Experimental Demonstration and a Two-Dimensional Model”, Physical Review Letters 108, 051103 (2012)
http://arxiv.org/abs/1112.3448

6 thoughts on “Now Playing: Core Collapse in 3D

  1. Gregg-WeberGregg Weber

    Is that AC motion or DC motion? By that is it something physically moving or is it the effect of something moving? A jet drops a bomb and you can see the expanding shockwave of an explosion. That is AC. The shrapnel going out is the DC.
    This reminds me of my old orange Lava Lamp. I wonder if one can send up to the ISS a basketball sized glass sphere with a heat source in the center and "lava" and clear liquid around it. Would it behave as such?

  2. Mark Zastrow

    Thanks for the great question Gregg. The motion depicted in the video is essentially "AC"—but if anything, it doesn’t quite convey the full scale of the "DC" motion. Specifically, the blue surface is the shock wave and the red surface corresponds to a surface of equal entropy. But this is still the implosion stage, so the physical "DC" motion of the particles is all *inward*, collapsing onto the neutron star. The blue shock wave is sort on a treadmill—it’s trying to move outward through the infalling gas.

    Interestingly, since the speed of the shock also depends on the material it moves through, as layers of different elements fall through the shock wave, the shock behaves differently! In fact, the researchers find that in their simulations, the arrival of the silicon/oxygen layer at the core is what stops the SASI behavior. It allows the shock wave to begin to expand, but still doesn’t quite trigger a runaway explosion.

    http://arxiv.org/abs/1303.6269

  3. Bruce

    Your welcome Mark. I’ve wondered about how neutrinos could power supernova explosions for many years. When you compare the assertions made about neutrinos it is easy to be bewildered. On the one hand we’re told that even at our distance from the sun the flux of neutrinos streaming out from the core of the sun is 64 billion per second per centimeter squared. They pass right though the earth with almost never an interaction. Then on the other hand we’re told that neutrino flux is what blows some types of supernovas to smithereens. What gives? The total flux of neutrinos from the sun is said to be 1.8E38/second. Just how large a neutrino flux would be needed to reverse the infall of several suns worth of material when neutrinos hardly ever interact with other particles? Perhaps conventional wisdom that neutrinos cause the shock wave in core collapse supernovae is flawed.

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