A new study suggests that Earth could, under certain conditions, survive the final phase of the Sun’s evolution, even though the planets in closer orbits, Mercury and Venus, will most likely be destroyed.
The research, published June 19 in the journal Astronomy & Astrophysics, is based on state-of-the-art computer simulations and stellar evolution models that reexamine the ultimate fate of the solar system, Earth Sky notes.
Although it does not refer to the possibility of maintaining life on Earth, the study proposes an alternative version for our planet, which until now was considered destined for certain extinction when the Sun turns into a red giant.
In about 5 billion years, the Sun will run out of hydrogen in its core and begin to expand significantly, entering the red giant phase, followed by an even more advanced stage of evolution, before becoming a white dwarf.
The researchers explain that at this stage, the Earth will be subject to two opposing forces: on the one hand, the expanding Sun’s tidal forces, which tend to pull the planet towards the star, and on the other hand, the loss of mass from the Sun, which reduces its gravity and could allow the Earth to move away into a wider orbit.
“Earth’s fate depends on a delicate balance between these two effects. If tidal forces dominate, the planet is swallowed up. If mass loss dominates, Earth escapes into a wider orbit,” explained Mats Esseldeurs, PhD student at KU Leuven University and lead author of the study.
To reach these conclusions, the researchers used models of stellar evolution and observations of stars in advanced stages of life, including a Sun-like star, L2 Puppis, located about 200 light-years away.
This star is losing mass at a high rate and is surrounded by a disk of matter, in which there could even be a very large planet, 12 to 16 times the mass of Jupiter.
Simulations show that although the Sun will expand its atmosphere to hundreds of times its present size, the loss of mass could weaken its gravitational pull enough that the Earth would “escape” of swallowing.
However, the researchers point out that there are still major uncertainties about how much mass the Sun will lose in its final stages of life.
Even if Earth could survive, models indicate that Mercury and Venus will not share the same fate and will most likely be destroyed in the red giant phase.
The study will be complemented by future observations, including by the European PLATO mission, which will study Earth-like planets around old stars and help to better understand the evolution of planetary systems.
