A team of astrophysicists and meteorology experts from the University of Exeter and the UK’s Met Office have embarked on the first, tentative steps to explore the potential climate of the recently-discovered Earth-mass exoplanet Proxima Centauri b.
This artist’s impression shows a view of the surface of the exoplanet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to the Solar System. The double star Alpha Centauri AB appears in the image to the upper-right of Proxima itself. Image credit: ESO / M. Kornmesser.
Proxima Centauri b, or simply Proxima b, was discovered in 2016 by Queen Mary University of London astronomer Dr. Guillem Anglada-Escudé and co-authors.
The planet orbits Proxima Centauri, a red dwarf star only 4.23 light-years away in the constellation Centaurus.
Early studies have suggested that Proxima b is slightly larger than Earth and sits within its star’s habitable zone, where liquid water could theoretically exist on the surface.
Now, Dr. Ian Boutle, a researcher at the Met Office and a honorary fellow at the University of Exeter, and co-authors have undertaken new research to explore the potential climate of Proxima b, towards the longer term goal of revealing whether it has the potential to support life.
Using a state-of-the-art model, which has been successfully used to study the Earth’s climate for several decades, the team simulated the climate of Proxima b if it were to have a similar atmospheric composition to our planet.
The scientists also explored a much simpler atmosphere, comprising of nitrogen with traces of carbon dioxide, as well as variations of the planets orbit. This allowed them to both compare with, and extend beyond, previous studies.
“We present results of simulations of the climate of the newly discovered planet Proxima Centauri b, performed using the Met Office Unified Model (UM),” the authors explained.
“We examined the responses of both an ‘Earth-like’ atmosphere and simplified nitrogen and trace carbon dioxide atmosphere to the radiation likely received by Proxima b.”
“Additionally, we explored the effects of orbital eccentricity on the planetary conditions using a range of eccentricities guided by the observational constraints.”
The results of the team’s simulations showed that Proxima b could have the potential to be habitable, and could exist in a remarkably stable climate regime.
However, much more work must be done to truly understand whether this planet can support, or indeed does support life of some form.
“Our research team looked at a number of different scenarios for the planet’s likely orbital configuration using a set of simulations,” said Dr. Boutle, lead author of the paper discussing the results in the journal Astronomy & Astrophysics (arXiv.org preprint).
“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.”
“One of the main features that distinguishes this planet from Earth is that the light from its star is mostly in the near-infrared,” said co-author Dr. James Manners, also from the Met Office and the University of Exeter.
“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.”
Using the UM model, the researchers found that both the tidally-locked and 3:2 resonance configurations result in regions of Proxima b able to host liquid water.
However, the 3:2 resonance example resulted in more substantial areas of the planet falling within this temperature range.
Additionally, they found that the expectation of an eccentric orbit, could lead to a further increase in the ‘habitability’ of this world.
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Ian A. Boutle et al. 2017. Exploring the climate of Proxima B with the Met Office Unified Model. A&A 601, A120; doi: 10.1051/0004-6361/201630020
