This year a more unique than rare celestial spectacle could rival, at least for a while, even the North Star, one of the brightest stars in the firmament. According to NASA, in fact, the T Corona Borealis (or T CrB) system, a binary system that is 3 thousand light years away from our planet, is destined to produce a nova in 2024: a very powerful explosion that will make T CrB visible to the naked eye for a few days in the night skies, and which will not be repeated for at least the next 80 years.
As we were saying, T CrB is a binary system, composed of a white dwarf and a red giant, one of the five present in the Milky Way which periodically give rise to the phenomenon known as a nova: an enormous thermonuclear explosion which drastically increases the brightness of the star system . The phenomenon – explains NASA – is due to the fact that the two stars are placed on a very narrow orbit, which makes the red giant unstable and determines the expulsion of its outermost layers, which are captured by the gravitational attraction of the companion white.
The gases in question consist mainly of hydrogen and helium, which accumulate little by little on the surface of the white dwarf, where they are compressed and heated by its gravity, until they reach the point of no return, in which pressure and temperature trigger a nuclear fusion reaction that quickly converts hydrogen into heavier materials, producing enormous amounts of energy and sweeping away the remaining gases accumulated on the surface. In this process, the star system increases its brightness by up to 10-12 magnitudes (practically the difference between a star that is difficult to see even with a telescope, and one that is clearly visible to the naked eye), and then turns off again within a few day. At that point, the accumulation of gas on the surface of the white dwarf begins again, until the next nova.
In the case of T CrB the entire cycle takes 80 years, and therefore this year will be the only opportunity to enjoy the nova live. It is therefore a good idea to be prepared, also because the explosion could occur at any time, in a period from February until next September. To start, NASA recommends familiarizing yourself with the Corona Borealis, the small constellation to which T CrB belongs and in which the nova will be visible as an extremely bright new star. To find it, simply remember that it is located between the larger Hercules and Bootes, which can also be identified by looking near two very bright stars: Vega and Arcturus.