New Earth-like habitable planet found orbiting nearest star

Scientists have discovered an Earth-like planet, orbiting the closest star to our Sun, which has temperature suitable for liquid water to exist on its surface and may be the nearest possible abode for life beyond our solar system.

An international team of astronomers found clear evidence of the planet about four light years away, orbiting Proxima Centauri, the closest star to our Solar System.

The new world, named Proxima b, orbits its cool red parent star every 11 days and has a temperature suitable for liquid water to exist on its surface, if it were present.

This rocky world is a little more massive than the Earth and is the closest exoplanet to us; it may even be the closest possible abode for life beyond our own Sun, researchers said.

Just 4.2 light-years from our Solar System sits a red dwarf star named Proxima Centauri.

This cool star in the constellation of Centaurus is too faint to be seen with the naked eye and is close to the much brighter pair of stars known as Alpha Centauri A and B.

During the first half of 2016, the HARPS spectrograph on the European Southern Observatory's 3.6-metre telescope at La Silla regularly observed Proxima Centauri.

The team of astronomers, called the Pale Red Dot campaign, led by Guillem Anglada-Escude of Queen Mary University of London was looking for a tiny back-and-forth wobble in the star caused by the gravitational pull of an orbiting planet.

In addition to data gathered by the Pale Red Dot campaign, the research incorporates contributions from scientists who have been observing Proxima Centauri for years.

"The first hints of a possible planet were spotted back in 2013, but the detection was not convincing," said Anglada-Escude.

The Pale Red Dot data, when combined with earlier observations, unveiled a truly exciting result.

At regular intervals, Proxima Centauri is approaching Earth at about 5 kilometres per hour and at opposite times in those cycles it is receding at the same speed.

This regular pattern repeats with a period of 11.2 days. Careful analysis of how tiny the resulting Doppler shifts were showed that they indicated the presence of a planet with a mass at least 1.3 times that of the Earth, orbiting about seven million kilometres from Proxima Centauri - only five per cent of the distance between the Earth and the Sun.

Although the planet companion, Proxima b, orbits much closer to its star than Mercury does to the Sun in our Solar System, the star itself is far fainter and cooler than the Sun.

As a result, Proxima b has an estimated temperature that - if water were present - would allow it in a liquid state on its surface, thus placing it within the so-called "habitable zone" around the star.

Despite the temperate orbit of Proxima b, the conditions on the surface may be strongly affected by the ultraviolet and X-ray flares from the star—far more intense than the Earth experiences from the Sun, researchers said.

The findings appear in the journal Nature.