Would it be possible to survive on a planet around a double-star system?

Tatooine-like planets, those orbiting around double or binary stars, also known as circumbinary planets (CBPs) – are no longer just science fiction. The Kepler spacecraft observed several transiting CBPs. Here we focus on circumbinary-type planets that move around the centre of mass of the double-star system in a relatively wide orbit.

The first requirement for survival on a CBP is that the planet remains dynamically stable. Gravitational perturbations from the binary can destabilise the circumbinary orbit. If this happens then the CBP is likely ejected from the system, or it could even collide with one of the stars. Both are not favourable scenarios for survivability. Secondly, if we agree to need liquid water for survival, and ideally a breathable atmosphere, the CBP should neither be too close nor too far from the binary.

Even if we manage to find a habitable

CBP, it’s not guaranteed to stay habitable indefinitely. Over timescales of billions of years the binary stars – assuming they are similar to the Sun – will evolve. In later stages the stars will lose a lot of mass when they evolve into white dwarfs. The mass loss could unbind the CBP, hurtling it into the darkness of space. If not, the dim light from the white dwarfs would usher in an indefinite ice age. We are fortunate to be living on a planet that, for now, is very accommodating to life.