Washington: International astronomers said today they have found the fourth potentially habitable planet outside our solar system with temperatures that could support water and life about 22 light-years from Earth.
The team analysed data from the European Southern Observatory about a star known as GJ 667C, which is known as an M-class dwarf star and puts out much less heat than our Sun.
However, at least three planets are orbiting close to the star, and one of them appears to be close enough that it likely absorbs about as much incoming light and energy as Earth, has similar surface temperatures and perhaps water.
The new rocky planet, GJ 667Cc, orbits its star every 28.15 days -- meaning its year equals about one Earth month -- and has a mass at least 4.5 times that of Earth, according to the research published in Astrophysical Journal Letters.
"This planet is the new best candidate to support liquid water and, perhaps, life as we know it," said Guillem Anglada-Escude who was with the Carnegie Institution for Science when he conducted the research but has since moved on to the University of Gottingen in Germany.
The theory about water, however, cannot be confirmed until astronomers learn more about the planet`s atmosphere.
Other planets circling the same star -- which is part of a three-star system -- could include a gas-giant and an additional super-Earth with an orbital period of 75 days, but more observations are needed to confirm that.
Some experts have been sceptical that M-class dwarf stars could have planets that support life because they are too dim and tend to have lots of solar flare activity which could send off lethal radiation to nearby planets.