Exoplanet Discovered in Habitable Zone of Alpha Centauri Star

On August 24, 2016 – just four months after the launch of Breakthrough Starshot – the European Southern Observatory announced the discovery of Proxima b, the first known exoplanet in the Alpha Centauri system, the closest star system to Earth.

This planet is currently envisaged as the primary target of an eventual Breakthrough Starshot interstellar mission.

The Alpha Centauri system comprises a binary pair of Sun-like stars, Alpha Centauri A and B, accompanied by Proxima Centauri, which at 4.22 light years is the closest star to the Sun. The new planet has roughly the mass of the Earth, and may have a rocky composition. Although it lies in the “habitable zone” of its star, where the temperature might allow liquid water, it is unknown at the moment whether it has either water or an atmosphere, or whether other conditions on its surface are suitable for life. These and other properties will be objects of intense investigation in the coming years.

The presence of the planet was originally detected by Mikko Tuomi of the University of Hertfordshire, UK, and confirmed by the ESO’s Pale Red Dot team, headed by Guillem Anglada-Escudé of Queen Mary University, UK, using spectrographic measurements from the La Silla Observatory and the Very Large Telescope in Chile. For more information on Proxima b, see their paper.