And again eyes to the sky

It seems that this year has decided to please everyone who likes to look into the night sky. I have already told you that in autumn we will be able to observe the comet. This is not all that happens, soon we will be able to see an even more rare event.

I think you all know that sometimes such events as supernova explosions happen in space. When this happens, a new, very bright star appears in the sky, often so bright that it can be seen even during the day. Some attribute the appearance of the Bethlehem star to this very phenomenon. But here's the trouble, according to Arizona State University astronomer Sumner Starfield, a supernova explosion occurs approximately every 100,000 years. This slightly reduces our chances of ever seeing this unique phenomenon with our own eyes.

But, as it often happens in nature, everything has its exceptions. In 1866, Irishman John Birmingham discovered something special. At a distance of 3,000 light years from Earth, there is a double star system in the constellation Corona Borealis. It is usually too dim to be seen with the naked eye. But about every 80 years, the exchange between its two stars causes a sharp nuclear explosion. The light from the explosion travels through space and reaches Earth. We can observe it as the appearance of a new star, as bright as Polaris. It appears only for a few days.

Map of the starry sky with the constellation of the Northern Crown and the Big Dipper next to it

How do periodic supernovae occur? The system consists of two stars. The first is a cold dying star called a red giant. It burned its hydrogen and expanded tremendously. The second is a white dwarf. This is the later stage of the star's death, its entire atmosphere has flown away and only an incredibly dense core remains. These stars have such a large difference in size that the white dwarf Corona Borealis takes 227 days to orbit its red giant.

An artist's concept of the binary star system known as T Coronae Borealis

The explosion occurs because the stars are so close that the material ejected by the red giant collects near the surface of the white dwarf. Once a white dwarf reaches a certain mass, which takes about 80 years, it gets hot enough to start an uncontrolled thermonuclear reaction..

This year, humanity will witness the explosion of this periodic supernova for the third time. The first time it happened was in 1866, when this phenomenon was discovered by John Birmingham. It happened again in 1946. Now it's the turn of the third time. It is predicted that the explosion should take place in the period until September 2024.

Sources:

• space.com
• sciencealert.com