Cosmic Jewellery Conundrum

160,000 light years from earth, on the outskirts of the milky way galaxy, lies Supernova 1987A (SN 1987A). SN 1987A is all that remains of the star Sanduleak -69 202 whose explosion showed modern astronomers the details of a core-collapse supernova for the first time in years. When the explosion was spotted in 2019, everything about the supernova appeared normal, however under closer inspection an anomaly began to show. In a similar fashion to the beautiful necklaces that adorn the necks of supermodels and celebrities, SN 1987A is surrounded by a ring of bright orbs which give off the appearance of a string of pearls. While this phenomenon has baffled scientists for a few years now, a new theory may explain the supernova’s fancy jewellery.

The supernova and the string of Pearls

SN 1987A is a member of a satellite galaxy dubbed the Large Magellanic cloud which orbits the rim of the milky way (hence the title of ‘satellite). Once initial research had been completed after the official discovery of the supernova, scientists began to contemplate possible theories behind the gorgeous pearls that adorn it. The most promising being that the Rayleigh-Taylor instability is the cause.

The Rayleigh-Taylor instability effectively explains the relationship between two fluids of differing densities when the two meet. Have you ever noticed the interesting shapes made in your morning coffee when you add your milk? This is due to the milk having a higher density than the coffee. Lord Rayleigh-Taylor noticed that this effect occurs because the material of higher density is attempting to fall to the bottom of the mug whilst the other pushes past it to get to the top. This effect causes the two liquids to create beautiful patterns as they attempt to move past each other, and the same this happens during a supernova. Scientists use the Rayleigh-Taylor theory to explain how the clumps of light came to be. The pearls are made out of hydrogen which was released by the explosion and has a higher density than the clouds of material released by the 1987A earlier on. When these two densities collided, it could have caused the string of pearls around SN 1987A to be formed. It has been obvious to researchers, however, that this cannot be the full explanation for the creation of the cosmic jewellery.

 Fashion Designer Theory

The second, and more promising, theory explored by scientists has been found to almost perfectly fit every variable in the equation, shedding some more light over the cosmic mystery. The theory in question relates to something called the Crow instability, which is the same rule that causes airplanes wakes to brake up.

On a plane, each wing generates lift which causes circular patterns of rotating air to be left behind in their wake. This circulating air can interact with the commonly seen trails of exhaust water vapour left behind as plane flies (called contrails), creating rotating patterns and distortions in the steam. As stated by Michael Wadas, author of this study and mechanical engineering graduate, “The Rayleigh-Taylor instability could tell you that there might be clumps, but it would be very difficult to pull a number out of it,”. The Crow instability, on the other hand, would give us the ability to predict the exact number of hydrogen pearls there are surrounding SN 1987A. The beginnings of a huge lead towards discovering the intricacies of this mysterious supernova.  

To fully test if the Crow instability could be at play here, simulations were conducted by Wadas and his team. The explosion of what was once a blue giant would have produce a lot of what is known as stellar wind. Because of this, a ring of hydrogen gas that had encircled the star was buffeted and pushed away. As the scientists re-enacted this situation, they noticed that, due to drag, the top and bottom areas of the hydrogen cloud were pushed away before the middle section. Subsequently the cloud curled in on itself, the crow instability was triggered and the hydrogen broke up into fairly even clumps encircling the supernova: a string of pearls.

Cosmic Case Closed

Using this simulation, the research team have predicted a total of 32 pearls all together, a number that is very close to the 30-40 that can be counted using images from the JWST. On top of this, further simulations that take Crows instability into account have predicted the creation of even more hydrogen blobs in the near future. This prediction was then enforced when images from the JWST that showed the beginnings of more clumps appearing were released in august last year. The work done by Wadas and the research team might also explain factors in other aspects of astrophysics. For example, the Crow instability may even be the explanation for when the dust around a star merges into planets, such as how earth was formed, however, further research on this subject must be completed before this is confirmed.  Overall, it is safe to say that the mystery of this fashionable supernova, after having baffled scientists for years, may finally have been decoded.