“We’ve expanded the range of potential configurations it could be habitable in,” Dr Mayne said. He noted this was also more of a thought experiment than concrete evidence of habitability, but it provides a good template for future observations.
However, as so little is known about Proxima b, the team had to make some assumptions in the model. For example, they assumed the entire planet was covered in water, although it likely might have land.
They also relied on it having one of two atmospheres. One was an Earth-like atmosphere, while another was more simple, being comprised of nitrogen and traces of carbon dioxide. We won’t know what the atmosphere of the planet is like for certain until we study the planet in more detail with upcoming observatories like the European Extremely Large Telescope (E-ELT) in 2024.
And they used two possible configurations for the motion of the planet too, one being tidally locked to the star with the same face always pointing towards it. The other was a 3:2 resonance, meaning it would rotate three times for every two orbits, similar to Mercury in our Solar System. The latter was found to have more regions of the planet being in a habitable temperature range.
And, excitingly, the team say this method can also be used to study other terrestrial exoplanets. It has been used before for gaseous worlds like hot Jupiters, gas giants in close orbits around their stars, but never before for rocky worlds. This means we can assess the habitability of other worlds if we know a bit of basic information about them.
Much more work will be needed to understand Proxima b. But as we get a better grasp on its atmosphere, this model might just help us work out what the conditions there are really like. And maybe at some point in the future via a project like Breakthrough Starshot, which wants to use a laser-powered sail to send a probe there in 20 years, we might find out for certain.