atomic_fungus (atomic_fungus) wrote,
atomic_fungus
atomic_fungus

#1503: Hybrid solar model?

No, I'm not talking about cars.

I was thinking, last night, about what we currently understand about the internal functions of stars, and some of the problems associated with the accepted models for solar function, and I had an idea.

The accepted model for the sun (and, by extension, stars in general) is that an immense cloud of (mostly) hydrogen collapses into a ball, and once the density gets high enough, fusion begins.

We've understood the basic processes for quite some time, and the theory matches what we know about the properties of matter very well.

Still, I was thinking about how it could be different and yet work well enough to fit all the observed properties of stars.

(The so-called "electric sun" theory is a non-starter in my book.)

I was thinking, what if the core of the sun contained a fission reaction?

We start with a huge gas cloud, as before. It's mostly hydrogen, but there are other elements in it--helium, lithium, carbon, etcetera, with the concentrations diminishing as the atomic weight goes up.

The gas cloud coalesces and collapses. Density at the core of the protostar rises, and with it, temperature. Whatever weird molecules exist in the gas cloud, the temperature soon rises high enough that these molecules are broken up, so we've got a bunch of free atoms.

At some point, near the core of the protostar--sooner or later--matter will enter a degenerate state where bare nuclei are rubbing against each other. And the heavier nuclei naturally gravitate towards the center of the star, leaving mostly hydrogen on the outside.

Here's where my thought diverges from accepted science. (Note: this is me playing around with an idea. I'm pretty sure our currently accepted theories about stars are more or less correct.)

When the star ignites, it's something like a supernova: infalling gas reaches the limits of compressibility, and there is a sort of "rebound" off of that--and this is enough to begin fusion. It happens fairly "soft" when a star ignites, which is why the whole thing doesn't blow itself up immediately. (As opposed to a supernova, which happens suddenly.)

But during this time when the infalling gas is bouncing off the limit of degeneracy, heavier elements are formed--much heavier--and as happens in a supernova, all sorts of really heavy nuclei are synthesized. Including uranium.

The star is, at this point, very hot, so it continues to emit light and heat even though it enters a temporary phase of relative inactivity. It takes time for the heavy elements to move together, but as they do, a fission reaction begins, catalyzed by neutrons coming from the still-fusing hydrogen layer.

And then the star begins shining in earnest.

In the core of the star you have a sort of natural fission reactor, which acts to keep the star very hot. On the outside you have a thick layer of fusing hydrogen. Neither one continues to function without the other: take away the fission reaction and the fusion will stop, but take away the fusion reaction and the fission will stop.

In fact, the fissile material need not be uranium. We find heavy nuclei convenient for building nuclear reactors, but in something like a star, radioactive lithium and other light radioactive isotopes may be just fine. (And in fact this model works better with light element fission than it does with heavy elements, because there's a ready source for the radioactive isotopes of light elements. Why not lithium? Or Carbon 14? Or...?)

This would explain why we don't see as many neutrinos from the sun as we expect. If the sun is purely fusion, it should emit a certain number of neutrinos, of which we could detect a certain smaller number. Yet we detect far fewer--and if this theory of mine were right, it would explain everything: we're not seeing them because they're not there. The sun is working perfectly and our understanding of fusion in the sun is correct, but it's not the whole story.

So, it explains why we don't see as many neutrinos as we should. What else?

Variability: it happens when the two cycles run out of sync. The fission cycle keeps the fusion cycle hot. The fusion cycle provides neutrons (and fuel) for the fission cycle. They're connected by a negative feedback loop; if either cycle slows down, the sun cools down and the other cycle is forced to limit its output. Once the two cycles reach parity, the sun heats up again.

The nice thing about this model is that you don't need to re-explain anything like supernovae, novae, or stellar oddities. Neutron stars and black holes are still possible ends for massive stars.

(Our sun will become a red giant in about 10 billion years. The fusion layer, as it becomes richer in helium, provides an ever-increasing amount of lithium to the core, and the core gets hotter. This makes the fusion layer get bigger, but not much hotter, so the star becomes a red giant.)

Again, it's just an interesting thought I had; you're not going to see me trying to convince people that the hybrid solar model is more correct than the currently accepted model for stars and their internal workings.

But WTF, if you don't take out your assumptions once in a while and think "What if...?" you're not going to learn anything new.
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