An international team of astronomers has discovered what they are calling a new “super-Earth,” which is seven times the size of Earth and has the right conditions to support life.

Called HD40307g, the new planet exists in a zone of a nearby star and is part of a six-planet system.

An artist's impression shows the very large super-Earth, left, with its host star and two other planets in the system, to its right. Called HD40307g, it takes 200 days to circle its host star. (J. Pinfield/University of Hertfordshire)

Scientists had already known about the star and its other three uninhabitable planets but after using an instrument that was more sensitive to wavelengths, they were able to discover another three, including the super-Earth.

A report, appearing in Astronomy and Astrophysics, said the super-Earth exists in an area that supports liquid water and is in the outermost orbit from the star.

Its orbit around the host star is at a similar distance to Earth’s orbit around our Sun and also gets a similar amount of energy from the star that Earth receives from the Sun. This means there is a stable atmosphere to support life. As well, the planet is likely to be rotating on its own axis as it orbits the star, producing a daytime and night-time effect, much like Earth.

“The longer the orbit of the new planet means that its climate and atmosphere may be just right to support life,” said Hugh Jones of the University of Hertfordshire, which participated in the research.

“Just as Goldilocks likes her porridge to be neither too hot nor too cold but just right, this planet, or indeed any moons that it has lie in an orbit comparable to Earth, increasing the probability of it being habitable.”

The planet orbits the star in about 200 Earth-days and now joins a growing list of 800 known planets beyond our solar system.

The super-Earth and its two sister planets were previously undetectable until the team used the Harps instrument at the European Southern Observatory’s facility in Chile. The instrument detects tiny changes in the colour of a star’s light triggered by a planet’s gravitational tug.

Lead author of the paper, Mikko Tuomi, said the instrument allowed for increased “sensitivity” and enabled the team to identify three new planets.