Vampire Stars’ That Explode from Overeating — How AI Might Uncover the Mystery

This will be considered a breakthrough in supernova research since it will enable the creation of thousands of models in under a second.

A team of astronomers has applied artificial intelligence for the purpose of studying what leads most White Dwarf Stars transform into explosions.

This energy is known as type Ia supernova and these energetic explosions might be responsible for creating heavy elements that are scattered in space. These are the elements that can take shape to form future stars, planets or even life as we sometimes like to generalize. Explosions that occur during Type Ia supernovas are also uniquely identifiable, meaning that astronomers refer to such events as ‘standard candles’ and use the results from Type Ia supernovas to measure colossal cosmic distances.

However, these extragalactic events are not similar to the supernovae involving the collapse of massive stars thus producing neutron stars and black holes. Type Ia supernovas occur as a result of a “white dwarf” star, which consists of the remains of a star, bonding with another star and accreting matter from it.

Nevertheless, although it is widely recognized that Type Ia supernovas represent one of the forces that have shaped cosmic development, and these stars have become one of the most indispensable tools in the astronomers’ catalogue, the exact mechanism of their behavior remains a mystery to this day.

”In the case of supernovas, we look at the spectrum of light emitted from the event, Spectra gives the intensity of light versus the wavelength and depends on the elements produced in the supernova hence, Depending on the way an element interacts with the passing light at any given wavelength, its signature would appear uniquely on the spectra,” said Mark Magee of the University of Warwick. It is possible to study these signatures to deduce what the elements in a supernova are created in addition to gaining more insight on how the supernovae exploded.

Why do white dwarfs blow their tops?

The hydrogen, the fuel for nuclear fusion at the center of the sun, will come to an end after approximately 5 billion years. The end of this fusion of hydrogen to helium will also stop the radiation pressure in which the sun is currently supported against its gravity.

The core of the sun will contract while its outer shell is still burning due to nuclear fusion, which will expand out. This will turn the sun into a red giant, a stage that will see the star grow to a size that can encompass the orbit of Mars. This means that the planets within the solar system with the Earth will be swallowed.

This red giant phase will last approximately 1 billion years which is about ten percent of the sun’s total lifetime. In this stage, the outer shell of the sun will expand and disperse thus cooling down. The final outcome will be a hot, dense stellar core or white dwarf, enveloped in a luminous shell of gas and dust known as a planetary nebula – despite the fact that it has no connection to planets. For the sun, the white dwarf phase shall be its last phase and its existence will come to an end.

Other stars similar in size to the sun also evolve into white dwarfs but if they are in a close binary system, this could be the end of the road. Despite this, some white dwarfs might ignite a supernova explosion as they exit the scene.

You will see, it’s just like how a vampire rises out of the grave to suck the blood of an innocent, the same way, if a corpse white dwarf is not far from a companion star or if the aforementioned star has expanded to its red giant phase it can start feeding on its victim’s stellar material.

Once again, matter from this donor star cannot directly accrete to the white dwarf’s surface due to conservation of angular momentum. It creates a disk between the donor star and the white dwarf, which is continually supplied with matter fed to the dense stellar remnant. This accumulated matter accumulates on the outer layer of the stellar remnant which causes the white dwarf to exceed what is referred as the Chandrasekhar mass, which is 1. It is 4 times the mass of the sun’s mass. This is the mass boundary that a star has to reach to undergo supernova.

The cannibalistic feeding of a white dwarf on a donor star ultimately gives rise to a runaway thermonuclear explosion: a Type Ia supernova is an example of an astronomical event rather than a material object.

While Type Ia supernovas and “core collapse” supernovas, which happen when very massive stars’ cores have collapsed and formed neutron stars or black holes, differ in that while feeding, white dwarfs are fully annihilated by the supernova explosion that occurs.

Since the University of Warwick’s team wanted to gain a better understanding of this process, it used machine learning. While using this type of AI, the team was able to advance the generation of simulations based on Type Ia supernovae which would normally require lots of time and resources. The team also said that typically one model can take anywhere between 10 to 90 minutes depending on the complexity of the model to be developed.

“Tonight we want to compare between hundreds or thousands of models to understand the supernova completely This is very impractical most of the times “ Magee explained. ‘The new work in our forthcoming articles will not follow this approach as outlined above; instead, we shall teach machine learning how hurricanes look like and then use it to generate models much faster. ”

He said that in a similar manner as human beings use AI to compose art or even write content, researchers are going to develop simulations of supernova. It allows the team to now compare the current output provided from AI simulations and real observations of other Type Ia supernovas.

“We’ll be able to produce thousands of models in under a second – this will be a massive leap forward for supernova studies,” Magee said. “From this data, we create models which is is compared with real supernovas to determine what kind of supernova it is and precisely how it has exploded. ”

However, the advantages of using this approach are not only confined to the issue of time. The improved accuracy of the AI-based process will also enable the researchers to more accurately identify the range of elements that are forged around Type Ia explosions and subsequently ejected into space.

‘To establish what type of explosion occurred it is necessary to analyze elements released by supernovas, as some types of explosions release were more of certain elements than others,’ Magee explained. “We can then correlate the properties of the explosion to properties of the supernova host galaxies and come up with a direct connection between the process of explosion and the type of white dwarf that exploded. ”

The team will now try to scale their process so that it can work for other supernovas including the ones that give rise to neutron stars and black holes. This could help in associating the characteristics of these supernovas to the galaxies in which they occur.

“With modern surveys, we finally have datasets of the size and quality to tackle some of the key remaining questions in supernova science: how exactly they explode,” said team member Thomas Killestein of the University of Turku. This and similar machine learning approaches make it possible to analyze more supernovae than earlier approaches in terms of the number, detail, and uniformity.

The team’s research was published in May in the Monthly Notices of the Royal Astronomical Society (MNRAS)

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