When will the Sun die? Answers from the Gaia satellite
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Thanks to data from the European satellite Gaia, a team of astrophysicists was able to describe precisely the future of our star, until its transformation into a red giant in 7 billion years.
How much longer will there be sunshine? This time, the question has nothing to do with this scorching summer. It's about looking much further ahead. A team of astrophysicists from the Nice Côte d'Azur Observatory has studied the evolution of our star over the next few billion years, thanks to data from the Gaia satellite launched in 2013 with the mission of mapping nearly 2 billion stars in our galaxy. This space telescope of the European Space Agency (ESA) had provided its third catalog on June 13, 2022, the DR3. It is from this one that researchers were able to draw the future of the Sun.
Tracing the "lifeline" of the Sun
The method used consists in comparing our star to others among the impressive Gaia catalog. The researchers focused their efforts on stars with a surface temperature between 3000 and 10000 K, knowing that the Sun is at about 6000 K. Then, they selected stars with the same mass and chemical composition as the Sun, but of different ages. The researchers have identified 5863 analogous stars that draw the future of ours. Its "life line" can be read on a Hertzsprung-Russel (HR) diagram which represents the luminosity as a function of the surface temperature for all stars.
Our star is in the middle age
For the moment, the Sun is precisely 4.57 billion years old. It fuses hydrogen in turn to form helium. These reactions of fusions release energy at the origin of its brightness. It is in the "mature age", a period of relative stability in terms of temperature and luminosity. Good for us... But the thermometer is slowly increasing and should reach a maximum when it will be 8 billion years old. This increase is due to the fact that more fusion reactions are occurring as its core contracts under the effect of gravitation.
Around 11 billion years, the trouble will begin. The Sun will then have fused all the hydrogen in its core. The fusion will continue in its upper layers which will then expand, significantly increasing the size of our star. It will then become a red giant, when it will be 11.8 billion years old. Then our star will slowly cool down to become a white dwarf, the final stage of its existence... A dull old age that will probably take place without witnesses: life on Earth should not survive the red giant phase of our star.