For life as we know it to exist, liquid water is a must. Of course it is possible that there are other forms of life that do not require water, but since that is all we know, that is going to give scientists the best basis for identifying signs of life from great distances. For the possibility of liquid water to exist on an exoplanet, it must be in its star's habitable zone.
Astronomers are particularly interested in finding a twin of the Earth: a rocky planet in its star’s habitable zone that is about the same size as us. Most of the exoplanets we have detected so far have been far too large to be rocky, but we have detected some “Super Earths” that are more massive than Earth, but less massive than Uranus. The term doesn’t include any information about planetary composition or habitability, though.
However, astronomers may soon be announcing the discovery of a planet with 1.1x the radius of Earth, residing in a habitable zone. Though there is no official announcement at this time, Tom Barclay from the NASA Ames Research Center who is working on the Kepler mission gave select information to those in attendance at the Search for Life Beyond the Solar System: Exoplanets, Biosignatures & Instruments (EBI2014) convention on Wednesday at the University of Arizona.
The results are not yet slated for publication and there will be no official announcement until then, according to Discovery News. Not a lot of specific information was given, but we do know that the planet orbits an M1 dwarf star, which is slightly smaller and less bright than our own sun. The planet belongs to a five-planet system and is on the outskirts of the habitable zone. There hasn’t been any information released about the composition of the planet, its orbit, or its distance from Earth.
While there is video available for the other presentations at EBI2014, this particular talk was not recorded due to the sensitive nature of some of the details. For now, we will have to wait for more details to be released after the paper has been published in a scientific journal.
Thanks to Barclay for the conference sneak peak of a new HZ exoplanet with 1.1 R_e . Can't wait to see the publications! #ebi2014
— Kim Bott (@HumanBott) March 19, 2014
Barclay shows new transiting system around M dwarf. 5 planets with outermost (1.1 Re) is towards outer edge of habitable zone. #ebi2014
— Nick Ballering (@nick_ballering) March 19, 2014