Researchers from the University of California have said that a planet located about 1,200 light-years away from Earth and has surface liquid water in all probabilities is a good prospect for a habitable world. The planet, which is situated in the direction of the constellation Lyra, has been named Kepler-62f. It is approximately 40 per cent larger in size than the Earth.
"At that size, Kepler-62f is within the range of planets that are likely to be rocky and possibly could have oceans," said Aomawa Shields, lead author and a astrophysics postdoctoral fellow. In 2013, the planetary system that includes Kepler-62f was discovered by NASA's Kepler mission, which identified Kepler-62f as the outermost of five planets that orbit a star that is smaller and cooler than the Sun. However, the information about its composition or atmosphere or the shape of its orbit was not revealed.
In order to establish whether the planet could sustain life, the team tried to determine what its atmosphere might be like and what the shape of its orbit might be. "We found there are multiple atmospheric compositions that allow it to be warm enough to have surface liquid water. This makes it a strong candidate for a habitable planet," added Shields.
0.04 per cent of the atmosphere is made up by carbon dioxide on Earth. Kepler-62f is much far away from its star as compared to the distance of Earth from the Sun. Hence it requires more carbon dioxide in order to be warm enough to maintain liquid water on its surface and avoid it to get freezed.
Many computer simulations were ran by the team and it was found that there were many scenarios that allow the planet to be habitable, as different amounts of carbon dioxide in its atmosphere were assumed. To be consistently habitable throughout its entire year, the planet would need an atmosphere which is 3 to 5 times thicker than that of the Earth and should be composed entirely of carbon dioxide, said Shields.
Given how far it is from its star, there would be a possibility of a high concentration of carbon dioxide in the planet because the gas could be build up in the planet's atmosphere because temperatures get colder to keep the planet warm. The scientists used an existing computer model called HNBody to make their calculations of the shape of the planet's possible orbital path. This research was published online in the journal Astrobiology.
Using the same technique, it could be understood whether exoplanets much closer to Earth could be habitable, said Shields. "This will help us understand how likely certain planets are to be habitable over a wide range of factors, for which we don't yet have data from telescopes," she noted.
Scientists have so far confirmed 2,300 exoplanets. A few thousand others have been considered as planet candidates. However, only a couple dozen are known to be in the "habitable zone".