Earth-mass planet found orbiting Proxima Centauri in habitable zone

Astronomers have made a very interesting discovery using telescopes belonging to the ESO and other facilities. The discovery is clear evidence that a planet is orbiting Proxima Centauri, the closest star to Earth. This planet is known as Proxima b and it orbits very close to its cool parent star with an orbit completed every 11 days. The scientists believe that the planet has surface temperatures that would allow liquid water to form on its surface.

Since the red dwarf star has a cool surface temperature, it is to dim to be seen with the naked eye. It lies a little over four light-years from our Solar System and is near a much brighter pair of stars called Alpha Centauri AB. Proxima Centauri has been studied in depth for the first half of 2016 as scientists and astronomers looked for the slight back and forth wobble of the star that would indicate gravitational pull of a planet in orbit, this was called the Pale Red Dot campaign.

The location of Proxima Centauri in the southern skies

Credit: Y. Beletsky (LCO)/ESO/ESA/NASA/M. Zamani

Guillem Anglada-Escudé explains the background to this unique search, "The first hints of a possible planet were spotted back in 2013, but the detection was not convincing. Since then we have worked hard to get further observations off the ground with help from ESO and others. The recent Pale Red Dot campaign has been about two years in the planning."

Credit: ESO/Pale Red Dot

Data collected indicates that the planet orbiting its star has a mass of at least 1.3 times that of Earth and orbits about 7 million kilometers from Proxima Centauri, about 5% of the distance Earth orbits from the Sun. Much study was put into Proxima Centauri because Red Dwarf stars have processes that can mimic the presence of a planet. The team took pains to eliminate this possibility by monitoring the changing brightness of the star carefully during the campaign using the ASH2 telescope at the San Pedro de Atacama Celestial Explorations Observatory in Chile and the Las Cumbres Observatory. Proxima b orbits its star much closer to the star than Mercury to the Sun, but the fainter star puts the planet in the habitable zone, however, being so close to its star could mean the surface is strongly affected by ultraviolet and X-ray flares from the star.