Why won't the supernova explode?

Jun 18, 2012 By Dr. Tony Phillips
A supercomputer model of a spinning core-collapse supernova. NuSTAR observations of actual supernova remnants will provide vital data for such models. Credit: Fiona Harrison

(Phys.org) -- Somewhere in the Milky Way, a massive old star is about to die a spectacular death. As its nuclear fuel runs out, the star begins to collapse under its own tremendous weight. Crushing pressure triggers new nuclear reactions, setting the stage for a terrifying blast. And then... nothing happens.

At least that's what supercomputers have been telling astrophysicists for decades. Many of the best computer models of supernovas fail to produce an . At the end of the , gravity wins the day and the star simply collapses.

Clearly, physicists are missing something.

"We don't fully understand how supernovas of work yet," says Fiona Harrison, an at the California Institute of Technology.

To figure out what’s going on, Harrison and colleagues would like to examine the inside of a real supernova while it's exploding. That's not possible, so they're doing the next best thing.

Using a telescope named "NuSTAR" --short for Nuclear Spectroscopic Telescope Array -- they'll be scanning the debris from supernovas as soon as possible after the blast.

Launched over the Pacific Ocean on June 13, 2012, by a Pegasus XL rocket, NuSTAR is the first space telescope that can focus very high-energy X-rays, producing images roughly 100 times sharper than those possible with previous high-energy X-ray telescopes.

NuSTAR will map the distribution of titanium-44 in supernova remnants like this one, Cassiopeia A, to search for evidence of asymmetries.

When NuSTAR finishes its check-out and becomes fully operational, scientists will use it to scan for clues etched into the pattern of elements spread throughout the explosion's debris.

"The distribution of the material in a supernova remnant tells you a lot about the original explosion,” says Harrison.

An element of particular interest is titanium-44. Creating this isotope of titanium through nuclear fusion requires a certain combination of energy, pressure, and raw materials. Inside the collapsing star, that combination occurs at a depth that's very special. Everything below that depth succumbs to gravity and collapses inward to form a black hole. Everything above that depth will be blown outward in the explosion. Titanium-44 is created right at the cusp.

So the pattern of how titanium-44 is spread throughout a supernova remnant can reveal a lot about what happened at that crucial threshold during the explosion. And with that information, scientists might be able to figure out what's wrong with their computer simulations.

The x-ray "light path" of the EPIC camera of the XMM-Newton satellite, a design similar to that used by NuSTAR. Credit: ESA/ESTEC.

Some scientists believe the computer models are too symmetrical. Until recently, even with powerful supercomputers, scientists have only been able to simulate a one-dimensional sliver of the star. Scientists just assume that the rest of the star behaves similarly, making the simulated implosion the same in all radial directions.

But what if that assumption is wrong?

"Asymmetries could be the key," Harrison says. In an asymmetrical collapse, outward forces could break through in some places even if the crush of is overpowering in others. Indeed, more recent, two-dimensional simulations suggest that asymmetries could help solve the mystery of the "non-exploding supernova."

If NuSTAR finds that titanium-44 is spread unevenly, it would be evidence that the explosions themselves were also asymmetrical, Harrison explains.

To detect titanium-44, NuSTAR needs to be able to focus very high energy X-rays. Titanium-44 is radioactive, and when it decays it releases photons with an energy of 68 thousand electron volts. Existing X-ray space telescopes, such as NASA's Chandra X-Ray Observatory, can focus X-rays only up to about 15 thousand electron volts.

Normal lenses can't focus X-rays at all. Glass bends X-rays only a miniscule amount—not enough to form an image.

X-ray telescopes use an entirely different kind of "lens" consisting of many concentric shells. They look a bit like the layers of a cylindrical onion.

Incoming X-rays pass between these layers, which guide the X-rays to the focal surface. It's not a lens, strictly speaking, because the X-rays reflect off the surfaces of the shells instead of passing through them, but the end result is the same.

The NuSTAR team has spent years perfecting delicate manufacturing techniques required to make high-precision X-ray optics for NuSTAR that work at energies as high as 79 thousand electron volts.

Their efforts could end up answering the question, "Why won't the supernova explode?"

This video is not supported by your browser at this time.
A new ScienceCast video explains how NASA's NuSTAR observatory will explore the mystery of exploding stars.

A video version of this story.

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User comments : 16

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deatopmg
2.6 / 5 (5) Jun 18, 2012
"Clearly, physicists are missing something."

Clearly, that us a gross understatement!
GSwift7
4 / 5 (4) Jun 18, 2012
Clearly, that us a gross understatement!


My initial reaction to your statement was to suggest a more tempered view, but after further thought, I might have to agree. I don't think I would have said it with such a cynical tone, but the truth is the truth. There are many big gaps in physics, and the funny thing is that we seem to be uncovering more gaps as our observations and modeling become better. It's like learning how to read, only to discover that you have a really poor vocabulary. :)
Husky
1 / 5 (1) Jun 18, 2012
i would guess uneven distribution of angular momentum has something to do with it, if you look at earth and stars, they are not perfectly round but spheroid, there tends to be a bulge near the equator as more momentum is contained there.

Now I would imagine that if this spheroid is about to contract/implode upon itselve, it would happen faster at the north/south pole , effectively magnifying the uneven momentum distribution, the black hole may form in a black discus shape before the lion share of the equotariol material is sucked in and as we know once a black hole is formed at the edge (equatorial accretion disc) violent x-rays are released as mass is sucked in, these x-rays could be the trigger
chromosome2
not rated yet Jun 18, 2012
We're designing telescopes around information carriers we didn't know *existed* a century ago. In a decade, we'll be seeing gravity waves, neutrinos (and their oscillation), thermal infrared, hard x-rays, everything in between, and heck, maybe even something completely new. For example, we know that "empty" space is a churning soup of constantly annihilating virtual particles, and we're already using it for random number generation. Imagine if we found a way to measure it, and use that for some kind of inferometry.. There's no saying what we'll know in a century :D
GSwift7
5 / 5 (2) Jun 19, 2012
to Husky:

I think what they are looking for is a lot more irregularity than an equatorial bulge. Think more along the lines of the non-uniform temperature of our own sun. Those variations in temperature corespond to variation in density. If a non-uniform object compacts itself with its own gravity, you may get a really lumpy object. Our models can't simulate that (lack of computing power and model complexity) so they are hoping to "cheat" by looking at actual observations, like a child looking at the answers in the back of the text book, lol.
Terriva
1 / 5 (1) Jun 19, 2012
IMO these simulations lack the modification of general relativity, which would lead to the dark matter phenomena. The dark matter particles are condensing around these dense stars, thus violating the buyoance condition at the surface like dishcover. The common hydrodynamic models of supernova cannot account into it and they do allow the free mixing of core and surface layers, which leads into less or more smooth collapse of supernova.
dzipo
3 / 5 (2) Jun 20, 2012
It's just such a stupid mistake.
In order for gravitational collapse to happen the body must release gravitational binding energy. And when core collapses but the outer shell can't channel that energy trough it it is just blown away.
So there is no such thing as runaway gravitational collapse.

But of course everybody knows that there are Black Holes and for them to exist there should be runaway gravitational collapse. So let's just patch this inconsistency and keep our beloved Black Holes intact. Darn
TkClick
not rated yet Jun 20, 2012
If I understood correctly, the computer simulations lead to the black holes, but they don't do it in explosive way. But the models which we can find on the web are using rather common hydrodynamics for simulation of Rayleigh instability.

IMO this is very rough approximation and essentially the waste of taxpayers money. For example, everyone knows, that the surface of very dense stars is not behaving like surface of fluid, but rather brittle solid because of eddy currents. But you cannot see it at these simulations at all.
TkClick
Jun 20, 2012
This comment has been removed by a moderator.
TkClick
1 / 5 (1) Jun 20, 2012
In common life we can interact with boson condensate from outside through magnetic field, which leads into so-called Meissner effect. The boson condensate of electrons is behaving like superfluid from inside, so it mediates the current without resistance (i.e. like the human sheeps in totalitarian society). But from outside the same very system is behaving like rigid brittle jelly, in which the magnet cannot move. It's because the highly compressed electrons are moving fast within superconductor and every attempt for change of their direction is therefore connected with high inertial and Lorentz forces. We can roughly say, that the particles in boson condensate are prone to change the first derivations of their motion, whereas they're resistant against zero and second derivations of their motion. From the same reason the dense plasma of collapsing stars cannot flow like the honey or mercury: it's quite different state of matter.
TkClick
1 / 5 (1) Jun 20, 2012
We can roughly simulate the behaviour of this matter with tixotropic starch dispersion, which becomes brittle when shaken. The rigid properties of starch dispersions are tested for their usage in bulletproof yet flexible armours. In all cases the extradimensional properties of particles manifest there: the irregular shape of starch particles represents the compactified extradimensions in the same way, like the highly compressed electrons or particles of plasma which are entangled together by their charge and magnetic fields within superconductors. Such a particles tend to move collectively without resistance in the same way like the people in totalitarian society, but they cannot change the direction of their motion (i.e. their acceleration) fast from the same reason: their extent is way larger, than the particles itself.
jsdarkdestruction
1 / 5 (1) Jun 20, 2012
It's just such a stupid mistake.
In order for gravitational collapse to happen the body must release gravitational binding energy. And when core collapses but the outer shell can't channel that energy trough it it is just blown away.
So there is no such thing as runaway gravitational collapse.

But of course everybody knows that there are Black Holes and for them to exist there should be runaway gravitational collapse. So let's just patch this inconsistency and keep our beloved Black Holes intact. Darn

and you've got a better solution based on real evidence and math? how can you possibley say that? you realize that eventually no matter what a large object is made of it creates a event horizon so if youve got some kind of plasma or white hole like object explanation for the supermassive black holes in galaxy centers its garbage.
dzipo
3 / 5 (3) Jun 21, 2012
and you've got a better solution based on real evidence and math? how can you possibley say that? you realize that eventually no matter what a large object is made of it creates a event horizon so if youve got some kind of plasma or white hole like object explanation for the supermassive black holes in galaxy centers its garbage.

One does not have to propose another garbage in place of particular garbage in order to say that particular garbage is garbage. It takes completely different arguments.

But if we nonetheless speak about proposing something new then it should be based on solid observed facts and reasonable extrapolations. If we don't have enough facts to propose something worth proposing then I prefer bare facts instead of some garbage.
A2G
not rated yet Jun 23, 2012
dzipo wrote, "One does not have to propose another garbage in place of particular garbage in order to say that particular garbage is garbage. It takes completely different arguments.

But if we nonetheless speak about proposing something new then it should be based on solid observed facts and reasonable extrapolations. If we don't have enough facts to propose something worth proposing then I prefer bare facts instead of some garbage."

Wow someone here who actually thinks for themselves without just accepting something because some "scientist" said so.

Congratulations, you have passed the logic test. Hopefully soon so will some others.

I agree with you that BH are BS are well.

Waiting for the real theory of everything instead of the patches on patches that we have now.

rah
not rated yet Jun 24, 2012
There might be a case where it's exploding but the explosion is crushed by gravity at the same time. No? It seems cool to think about it anyway.
SteveL
5 / 5 (1) Jun 24, 2012
IMO this is very rough approximation and essentially the waste of taxpayers money.
Even following a wrong path has value when assuring due diligence in research.
GSwift7
not rated yet Jun 25, 2012
There might be a case where it's exploding but the explosion is crushed by gravity at the same time. No? It seems cool to think about it anyway.


lol, go back and read the article again. The problem isn't that supernovae don't happen. The problem is that our models don't predict a supernova. Since we know there are supernovae (we have seen them), our models must need modification. Modeling what actually happens in a supernova, in 3-D, is beyond our ability right now. So, what we have is an oversimplified approximation of what a small piece of a supernova should look like. The catch is, that we don't know enough about a supernova to make the oversimplified approximation close enough to reality so that it works. It most likely does NOT mean that anybody is going to re-write the laws of physics. Think more along the lines of tweaking the parameters, adjusting constants, etc.