Media ReleaseFrom: Springer Nature
An Earth-like planet around the Sun’s closest neighbour
The discovery of a small, rocky planet candidate orbiting the Sun’s closest stellar neighbour, Proxima Centauri, is reported in this week’s Nature. The planet, named Proxima b, has a mass about 1.3 times that of the Earth and its temperature is within the range where water could theoretically be liquid on its surface.
Proxima Centauri is a red dwarf star that lies just over four light years from our Solar System and that is one of the best-studied low-mass stars. Guillem Anglada-Escudé and colleagues analysed Doppler measurements collected by two European Southern Observatory telescopes between 2000 and 2014 and a series of observations collected between 19 January and 31 March 2016. Doppler data can be used to measure tiny movements of a host star that result from the gravitational pull of a potential orbiting planet. The authors’ observations are consistent with the presence of a warm, Earth-mass planet that orbits Proxima Centauri every 11.2 days at a distance of about 7.5 million kilometres, or around 5 per cent of the Earth–Sun distance. The orbital period places Proxima b within the temperate zone of its star, which means the planet’s surface temperature could, in principle, support liquid water.
The habitability of planets like Proxima b — in terms of sustaining an atmosphere and liquid water — is debated, and further research will be needed over the next decades to attempt to characterize the planet’s atmosphere and assess whether it could support life. Moreover, Proxima b’s close orbit around its star means that the planet suffers from X-ray fluxes that are much more intense than those experienced by Earth; it is unknown whether the planet has a protective magnetic field as Earth does.
In the coming centuries, robotic exploration of Proxima b may become possible. “Proxima Centauri will exist for several hundreds or thousands of times longer than the Sun,” concludes Artie Hatzes in an accompanying News & Views article. “Any life on the planet could still be evolving long after our Sun has died.”
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