Nearby super-Earth may be habitable

An Earth-like planet enjoying conditions that might be suitable for life has been discovered by an international team of astronomers. It is being dubbed a super-Earth, because it is at least seven times more massive than our own world. It is thought to be made of rock and may have an Earth-like climate.

An artist’s impression of super-Earth HD40307g with its host star and two other planets to the right. Credit: J. Pinfield, for the RoPACS network at the University of Hertfordshire

The planet, which lies just 42 light-years away in the southern constellation of Pictor, the easel, orbits its own sun in the so-called habitable zone where water can exist as a liquid.

It is one of six planets in the new alien solar system around a star labelled HD 40307 and was identified by astronomers led by Mikko Tuomi, of the UK’s University of Hertfordshire, and Guillem Anglada-Escude, of University of Goettingen in Germany.

Previously only three planets were known to be orbiting the star and at distances too close for life. But closer examination by the team, which involved removing fake signals caused by stellar activity, revealed the existence of three more worlds.

Mikko Tuomi said: “We pioneered new data analysis techniques including the use of the wavelength as a filter to reduce the influence of activity on the signal from this star. This significantly increased our sensitivity and enabled us to reveal three new super-Earth planets around the star, making it into a six-planet system.”

The planet that has sparked greatest interest is the furthest out from the star and is labelled HD 40307g. It is orbiting at a similar distance from its star as the Earth is from the Sun and to enjoy similar levels of energy, or warmth and sunshine.

Such conditions increase the probability of the planet being being habitable. As well as being suitable for liquid water and a stable atmosphere, it is likely to be rotating on its own axis so that any aliens would enjoy an Earth-like day and night.

Guillem Angla-Escude said: “The star HD 40307, is a perfectly quiet old dwarf star, so there is no reason why such a planet could not sustain an Earth-like climate.”

Hugh Jones, also of the University of Hertfordshire, said: “The longer orbit of the new planet means that its climate and atmosphere may be just right to support life. Just as Goldilocks liked her porridge to be neither too hot nor too cold but just right, this planet or indeed any moons that is has lie in an orbit comparable to Earth, increasing the probability of it being habitable.”

Earlier this year the Kepler spacecraft found a planet with a similar orbit, but much further away. That world, labelled Kepler 22b, lies 600 light-years from Earth.

Mikko Tuomi carried out this work as a member of the European science network RoPACS (Rocky Planets Around Cool Stars) which is led from the University of Hertfordshire.

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