So this blog’s called Supernova Condensate, but I realise I’ve never actually written about supernova condensate! Time to fix that, I think…
Supernova condensate, often abbreviated to SuNoCon (which sounds like it should be a convention somewhere), is exactly that. Hot material from a supernova, expelled at high speeds from an exploding star, cooling and condensing into high temperature dust. Supernova dust is actually a fairly big source of cosmic dust. In fact, supernovae are a major source of many of the elements we all take for granted. So in the ridiculous pressures a supernova creates, nuclear fusion goes crazy – forming a veritable cornucopia of atoms and isotopes. Certain unusual nuclear isotopes, like 26Al and 56Fe (among others) are formed readily in supernovae. Uranium, for instance, can only really be created by a supernova — which is part of the reason we know that at least one occured in our neighbourhood shortly before the solar system formed. It’s interesting to think that fission reactors are actually using energy that came from a supernova; energy that’s been stored in uranium atoms ever since.
The physics behind the actual formation of supernova condensates are, quite frankly, fascinating. Shock waves, not only from the initial supernova, but from the central neutron star left behind (at least by Type II supernovae) cause Rayleigh-Taylor instabilities. Which look a bit like this…
These should be in sync. If they’re not, try refreshing the page.
These are two views of the same model (taken from the SciDAC Computational Astrophysics Consortium). The one on the left shows thermal mixing of material, while the one on the right shows the chemical reaction rates (bluer are faster) as a result of the turbulence in the instability. Simply put, turbulence causes small regions of higher density, and as any high school chemistry student should know, a higher density means a faster chemical reaction. Rayleigh-Taylor instabilities (and related mechanisms) occur in any place where two fluids of different density meet. The next time you see a lava lamp — the wax is actually doing a similar thing as it rises up the lamp.
It’s through these instabilities that supernova remnants like the Crab nebula form filaments (called “fingers”) like the ones in the image below. These filamentary structures are startlingly intricate, due to the complexity of those Rayleigh-Taylor instabilities. Those regions with high reaction rates cause more condensates to form, trailing behind the shock front. In a more in-depth model, you’d be able to see tiny swirling vortices all around the flowing material, swirling and forming ideal places for chemical reactions to take place.
In this image, those long filaments are caused by an expanding bubble of hot ionised particles from the Crab pulsar slamming into the remaining supernova material. As a result, any remaining gasses and atoms condense further, forming the beautiful structure we see. Messier liked it so much, he put his name on it it became the first object in his catalogue.
Supernova condensates are extremely stable to high temperatures. It takes a lot to vapourise them. The Crab nebula may have formed a thousand years ago, but it’s still several thousand degrees in temperature. Understandably then, only the most stable chemical structures would be able to survive such an environment — any weaker chemical bonds would be fragmented at those temperatures. That’s chemical evolution in one of its purest forms. Essentially, only the strongest will survive. Immensely stable things like titanium sulfides, iron oxides and siicon carbides abound in these places. Once formed, they act like seed nuclei, growing rapidly just like snowflakes in a cloud. Titanium sulfides, in particular, are expected to dominate certain parts of a supernova explosion.
The thing is, we’ve found those high temperature condensates in meteorites, together with the unusual isotopes I mentioned before. Crystals trapped in silicate rocks that predate the Earth itself. Again, this is more evidence for a supernova kick starting the birth of the Sun. After all, that supernova debris had to come from somewhere, and a supernova shockwave would likely cause a nearby nebula to start collapsing into stars.
In a poetic (but not entirely accurate) way, you could argue that as the Sun originally condensed from interstellar gas due to a nearby supernova, that makes the Sun a supernova condensate too. Whimsical, perhaps, but a thought to meditate on, I’m sure you’ll agree!