Nothing in the world lasts forever, not even our life and the light-giving star of the Sun. According to data from the European Space Agency's Gaia probe, the Sun is currently in middle age, estimated to be 4.57 billion years old. The space agency's star mapping mission has revealed more information about the Sun's fate and how it will evolve. No need to worry, though, because we won't be here until then.
The study seeks to predict the future of the Sun by identifying how stars of similar mass and composition will evolve. According to published data, the Sun is currently fusing its hydrogen core with helium, a process known as nuclear fusion, and is generally rather stable.
But the giant star eventually dies. It will happen because it will get hotter and hotter and then gradually run out of hydrogen. To bring in hydrogen, the core shrinks to form a hydrogen shell. While the core contracts, the Sun's outer atmosphere expands, eating away at Earth and even engulfing Mars. This turns the Sun into a red giant, lowering its surface temperature.
When the Sun's core eventually runs out of both gases (hydrogen and helium), it sheds all of its outer material and forms a planetary nebula. Meanwhile, the core will continue to cool and collapse into a dull white dwarf.
A star in our solar system is expected to reach its maximum temperature at an age of approximately 8 billion years. It will then cool and expand further to become a giant red star. It will reach the end of its life at the age of 10-11 billion years.
Orlagh Creevey of the Observatoire de la Côte d'Azur in France and collaborators from the Gaia 8 Coordination Unit combed through the data, looking for the most precise star observations the spacecraft could offer. They focused on stars that have a surface temperature between 3000 K and 10000 K, because such stars are essentially similar to the Sun, which has a surface temperature of 6000 K. They are also the longest-lived stars in the galaxy.
"If we don't understand our own Sun, and there are many things we don't know about it, how can we expect to understand all the other stars that make up our beautiful galaxy," Orlagh said in a statement.
Gaia is ESA's space observatory designed for astrometry (measuring the positions, distances and movements of stars with unprecedented precision). It was launched in 2013 and is expected to be operational until 2025.
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