This artists impression shows the view from the exoplanet Gliese 667Cd looking towards the planets parent star (Gliese 667C). In the background to the right the more distant stars in this triple system (Gliese 667A and Gliese 667B) are visible and to the left in the sky one of the other planets, the newly discovered Gliese 667Ce, can be seen as a crescent.ESO/M. Kornmesser
This diagram shows the system of planets around the star Gliese 667C. A record-breaking three planets in this system are super-Earths lying in the zone around the star where liquid water could exist, making them possible candidates for the presence of life. This is the first system found with a fully packed habitable zone. The relative approximate sizes of the planets and the parent star are shown to scale, but not their relative separations.ESO
This picture shows the sky around multiple star Gliese 667. The bright star at the centre is Gliese 667 A and B, the two main components of the system, which cannot be separated in this image. Gliese 667C, the third component, is visible as a bright star, very close and just under A and B, still in the glare of these brighter stars.ESO
Astronomers discovered a solar system packed with planets three of which are habitable -- meaning in the zone around the star where liquid water could exist, making them possible candidates for the presence of life.
The Gliese 667C star is orbited between five and seven planets and is part of a triple star system known as Gliese 667.
"We identified three strong signals in the star before, but it was possible that smaller planets were hidden in the data," said Guillem Anglada-Escudé of the University of Göttingen in Germany, who led the study. "We reexamined the existing data, added some new observations, and applied two different data analysis methods especially designed to deal with multi-planet signal detection."
'There are five very secure signals and up to seven low-mass planets in orbits around the star.'
- Guillem Anglada-Escudé of the University of Göttingen
"Both methods yielded the same answer: There are five very secure signals and up to seven low-mass planets in short-period orbits around the star."
The Gliese 667C solar system is strikingly similar to ours and the three planets identified as habitable are confirmed to be super-Earths: planets that have more mass than Earth but less mass than larger planets like Uranus and Neptune.
The star is just 22 light-years away in the constellation of Scorpius (The Scorpion). This is quite close to our solar system, astronomers said -- within the Sun’s neighborhood, so to speak -- and much closer than the star systems investigated using telescopes such as the planet-hunting Kepler space telescope.
"This is the first time that three such planets have been spotted orbiting in this zone in the same system," astronomer Paul Butler of the Carnegie Institute for Science who participated in the study said.
Similar systems have been found before and are very common in the Milky Way, however, most of these systems are built around Sun-like stars and are too hot to be habitable.
The Gliese 667C system is the first example of a system that contains multiple habitable planets surrounding a low-mass star.
The discovery of more systems like Gliese 667C could mean that the amount of potentially habitable planets in our galaxy are more numerous than believed.