An artist’s impression of the surface of Proxima B. Image courtesy of ESO/M. Kornmesser
The quest to discover whether a planet orbiting our closest neighboring star, Proxima Centauri (4.2 light years or 25 trillion miles from Earth), has the potential to support life has taken a new, exhilarating twist. The planet was only discovered in August 2016, and is thought to be of similar size to Earth, creating the possibility that it could have an `Earth-like’ atmosphere. Scientists from the University of Exeter have embarked on their first, tentative steps to explore the potential climate of the exoplanet, known as Proxima B.
Early studies have suggested that the planet is in the habitable zone of its star Proxima Centauri. Using the state-of-the-art Met Office Unified Model, which has been successfully used to study 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 own Earth. The team 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.
Crucially, the results of the 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. Dr Ian Boutle explained: “Our research team looked at a number of different scenarios for the planet’s likely orbital configuration using a set of simulations. 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 3 times on its axis for every 2 orbits around the sun (a 3:2 resonance), would affect the environment.”
Dr James Manners added: “One of the main features that distinguishes this planet from Earth is that the light from its star is mostly in the near infra-red. These frequencies of light interact much more strongly with water vapour and carbon dioxide in the atmosphere which affects the climate that emerges in our model.” Using the Met Office software, the Unified Model, the team found that both the tidally-locked and 3:2 resonance configurations result in regions of the planet 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.
Dr Nathan Mayne added: “With the project we have at Exeter we are trying to not only understand the somewhat bewildering diversity of exoplanets being discovered, but also exploit this to hopefully improve our understanding of how our own climate has and will evolve.”
http://www.exeter.ac.uk/news/featurednews/title_583299_en.html
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