In 1967, the singer Nicoletta evoked the disappearance of our star in her famous hit“Il est mort le Soleil”, covered a year later by the legendary Ray Charles. As poetic as they are, the lyrics of these songs do not augur well for the fatal fate that awaits the star.
In some 5 billion years, the one that is today only a yellow dwarf should end its life in the form of a huge planetary nebula, as revealed by a study published in 2018 in the journal Nature Astronomy.
From the red giant…
Scientists knew until now that in the last hours of its life, the Sun would turn into a red giant, a star with a diameter 100 times larger than today. But the new study by an international team of researchers now goes further.
With the help of powerful computer modeling, specialists have indeed managed to simulate the events that should follow the transformation of the Sun into a red giant. After this phase, our star should continue its slow agony and lose almost half of its mass, torn from its most superficial layers.
… To the white dwarf
After they have been carried away at nearly 20 kilometers per second, it will be the turn of the heart of the star to undergo violent transformations. According to the model developed by the researchers, the center of the dying Sun should quickly heat up and thus generate X-rays and ultraviolet rays that will transform the outermost strata of the star into a dazzling plasma ring.
“ What we have shown is that the core of the Sun will be quite hot five to ten thousand years after the outer layers have been ejected,” says Albert Zijlstra, professor of astrophysics at the University of Manchester. During this ten millennia, what will remain of the Sun should radiate from its rays the immensity that surrounds it. These processes will eventually lead to the formation of the famous planetary nebula announced by scientists.
Planetary nebulae represent the end of 90% of active stars and mark the transition from red giant status to white dwarf status, a celestial body much smaller and denser than a normal star. However, the Sun may not have formed such a structure. According to astronomers, it is in terms of mass at the lower limit of celestial bodies capable of forming a planetary nebula.
“These planetary nebulae are the most beautiful objects in the sky, and even if the Sun should only be a faint one, it will be visible from nearby galaxies,” predicts Albert Zijlstra. “If you lived in the Andromeda galaxy,2 million light-years away, you should still be able to see it,” promises Albert Zijlstra. One thing is certain, it is not from Earth that potential spectators will be able to observe the show.
Long before its death, and the events described by the researchers using their modeling, the Sun should indeed already begin a spectacular transformation, at the origin of the eradication of all terrestrial life. Within about 2 billion years, our star will have reached such a temperature that the heat emitted towards our planet will cause the oceans to boil.
Hostile living conditions leave little hope of survival. “Itwon’t be a very nice place,”concedes Albert Zijlstra. A sweet euphemism that would probably not have denied the poets of the song.