A group of astrophysicists and meteorologists at the University of Exeter explored the possible habitability of Proxima b, an Earth-sized planet discovered orbiting the star closest to our solar system, Proxima Centauri, using a computer model designed to study Earth’s climate.
Proxima b was discovered in August 2016 in the habitable zone of its parent red dwarf star, located 4.2 light years from Earth.
If it has an atmosphere and structure like those of Earth, the planet could have liquid water on its surface and possibly harbor life.
Researchers used the Met Office Unified Model, a simulation scientists have utilized for decades to study Earth’s climate, simulating possible environments for Proxima b, including one with an Earth-like atmosphere and another with a simpler atmosphere.
“Our research team looked at a number of different scenarios for the planet’s likely orbital configuration, using a set of simulations,” explained Ian Boutle, lead author of a paper on the study’s findings published in the journal Astronomy and Astrophysics.
“As well as examining how the climate would behave if the planet was ‘tidally-locked’ (where one day is the same length as one year), we also looked at how an orbit similar to Mercury, which rotates three times on its axis for every two orbits around the Sun (a 3:2 resonance), would affect the environment.”
In the simpler atmosphere model, the planet’s atmosphere contained mostly nitrogen, along with small amounts of carbon dioxide. Several orbital variations were explored using this model.
Significantly, the simulations indicated Proxima b could be habitable if its climate is stable, whether the planet is tidally locked to its star or in a 3:2 resonance orbit.
Under the latter scenario, the planet could support life only if enough of its regions had temperatures capable of sustaining liquid water on its surface.
An eccentric rather than circular orbit could enhance Proxima b’s chances of being habitable.
“One of the main features that distinguish this planet from Earth is that the light from its star is mostly in the near-infrared. These frequencies of light interact much more strongly with water vapor and carbon dioxide in the atmosphere, which affects the climate that emerges in our model,” said James Manners, a co-author of the paper.