🌍 A planet like Earth could exist with two suns

A rocky planet could maintain conditions favorable to liquid water even under a sky dominated by two stars.

Astronomers tested this possibility in several nearby star systems, including 70 Ophiuchi, located about 16.7 light-years away. This system contains two stars that orbit each other at a relatively large distance. No planet has currently been confirmed there, but the researchers simulated what would happen to worlds placed around each of the stars.

The problem comes from gravity. In our Solar System, the Sun’s mass overwhelmingly dominates Earth’s motion. With two stars, the pair can gradually distort a planet’s orbit. The planet may then move much closer to or farther away from its star, or even be ejected from the system.

To test this scenario, the team digitally created numerous planets in the habitable zone. This region corresponds to distances where a planet could receive an amount of energy compatible with liquid water on its surface, under certain conditions.

The results are encouraging for 70 Ophiuchi. The simulations indicate that planets can maintain stable orbits in the habitable zones of both stars. Variations in their trajectories generally remain moderate enough for them to continue receiving an amount of energy compatible with the limits adopted by the researchers.

The orientation of the orbit nevertheless plays a role. A planet orbiting in the same plane as the two stars is more stable under the conditions studied. With an orbit inclined at 45°, the disturbances become significant. Its distance from its star varies, causing marked changes in the energy it receives.

The researchers also studied 36 Ophiuchi and Gamma Leonis. The former also has regions where planets could remain stable for long periods. The situation differs around Gamma Leonis: the movements of its two stars cause the habitable zones under study to vary.

A low-mass planet could still evade current observations of 70 Ophiuchi, and the calculations show that such a planet is not automatically doomed by the presence of a second star.

This information could assist future observatories tasked with directly searching for nearby Earth-like worlds. The authors specifically mention the future Habitable Worlds Observatory.

If a planet is detected around 70 Ophiuchi, its actual orbit can then be compared with these simulations to assess its stability over long periods.