What does a star that is preparing to become a supernova look like

Scientists have modeled what a star should look like, which in just a few years should turn into a supernova. It should be covered by a characteristic shell of material thrown from the surface.

Supernova before the explosion. Source: www.newscientist.com

What should a star look like before a supernova explosion

A supernova explosion is a catastrophic event that not only almost completely destroys a star that turns into a neutron star or a black hole, but also affects its entire environment. Supernovae are visible through the entire Galaxy. This means that at a distance of several light-years from it, the energy density is sufficient to destroy life on planets. 

Therefore, it is very important to know if there are any stars around that are ready to turn into supernovae. There are several types of the latter. It is reliably known that type II-P supernovae remain bright for a very long time and are formed from red supergiants. There are several stars in our sky that could follow this path, including Betelgeuse, which changed its brightness significantly a few years ago.

However, this stage does not last long only by cosmic standards. In fact, it can drag on for hundreds of thousands and even millions of years. And the same Betelgeuse became a red giant just a few centuries ago. Scientists decided to find out if it was possible to find out again a few years before the explosion.

They studied astronomical archives in detail and found several dozen supernovae that were observed several years before the explosion. All of them have a characteristic shell of gas, which is much thicker than is now observed in Betelgeuse.

How the shell is formed

Scientists are sure that it is this shell that is responsible for the long-term preservation of the brightness of type II-P supernovae. It is the first to perceive the shock wave and heats up. There is an absorption of energy in the gamma range and its re-emission in the visible region of the spectrum. 

Scientists are interested in how such a shell is formed before a supernova explosion. They considered two possible models. According to the first one, it is formed over millions of years under the influence of a powerful “stellar wind” that gradually destroys the outer layers of the star.

According to the second shell, it is formed due to small explosions that occur at dawn a few years before turning into a supernova. The researchers modeled what the star should look like in each of these cases.

They compared the results with what was observed on stars that then exploded as supernovae. It turned out that the observed picture in reality is not at all similar to the one assumed by the model with a long process of formation.

So, a few years or decades before the supernova flare, which is preparing to become it, can be easily recognized. A series of explosions should occur on it, as a result of which a dense shell of gas is formed. As soon as you see something like that, run away.

According to www.space.com

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