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What’s the weather like on Proxima b?

The nearest known exoplanet – orbiting the star Proxima Centauri – is only 4.2 light-years away. Does it have liquid water? An atmosphere? Weather? Scientists just announced the first tentative steps to explore those possibilities.

Artist’s concept of Proxima b, the nearest known exoplanet. It orbits the star Proxima in the Alpha Centauri star system, 4.2 light-years away. Image via ESO.

The University of Exeter said today (May 15, 2017) that its researchers have taken their first, tentative steps to explore the potential climate of the nearest known exoplanet, Proxima b. We’ve known about this planet for less than a year, since August, 2016.. At 4.2 light-years or 25 trillion miles from Earth, Proxima b is the nearest known exoplanet, or planet orbiting a sun besides our sun. What’s more, Proxima b is similar in size to Earth, and it lies in the habitable zone of its star. That means it’s possible that liquid water exists on its surface. Does Proxima b have liquid water? Does it have an atmosphere and a climate? No one knows. But scientists are now taking some steps to explore the theoretical aspects of this possibility.

Their initial research is being published May 16, 2017 in the peer-reviewed journal Astronomy & Astrophysics.

These scientists used a computer model known as the Met Office Unified Model to conduct their study. They say this computer model has been used successfully to study Earth’s climate for several decades. Their statement explained:

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 nitrogen with traces of carbon dioxide, as well as variations of the planet’s 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.

The study was led by Ian Boutle, who said:

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 three times on its axis for every two orbits around the sun (a 3:2 resonance), would affect the environment.

Another one of the researchers, 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 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.

Using the Met Office software, 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.

A third author on the paper, Nathan Mayne of University of Exeter, said:

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.

Bottom line: Scientists have embarked on their first, tentative steps to explore the potential climate of the nearest known exoplanet, Proxima b.

Deborah Byrd

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