New super-Earth in six-planet system may be just right to support life
The exoplanet’s orbit around its host star is at a similar distance to Earth’s orbit around the Sun.
November 8, 2012
A new super-Earth planet that may have an Earth-like climate and be just right to support life has been discovered around a nearby star by an international team of astronomers.
This artist’s impression shows HD40307g in the foreground with its host star HD40307 and two other planets in the system (on the right-hand side). The depicted atmosphere and continents are not detected or constrained by this work. // Credit: J. Pinfield for the RoPACS network at the University of Hertfordshire
The new super-Earth planet exists in the habitable zone of a nearby star and is part of a six-planet system. The system was previously thought to contain three planets in orbits too close to the star to support liquid water. By avoiding fake signals caused by stellar activity, the researchers have identified three new super-Earth planet candidates also in orbit.
“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,” said Mikko Tuomi from the University of Hertfordshire, United Kingdom. “This significantly increased our sensitivity and enabled us to reveal three new super-Earth planets around the star known as HD 40307, making it into a six-planet system.”
Of the new planets, the one of greatest interest is the one with the outermost orbit from the star -– with a mass at least seven times that of Earth. Its orbit around the host star is at a similar distance to Earth’s orbit around our Sun, so it receives a similar amount of energy from the star as the Earth receives from the Sun — increasing the probability of it being habitable. This is where the presence of liquid water and stable atmospheres to support life is possible, and, more importantly, the planet is likely to be rotating on its own axis as it orbits around the star, creating a daytime and nighttime effect on the planet, which would be better at creating an Earth-like environment.
“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,” said Guillem Angla-Escude from the University of Goettingen, Germany.
“The longer orbit of the new planet means that its climate and atmosphere may be just right to support life,” said Hugh Jones from the University of Hertfordshire. “Just as Goldilocks liked 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.”
Earlier this year, the Kepler spacecraft found a planet with a similar orbit. However, Kepler 22d is located 600 light-years from Earth, whereas this new super-Earth planet known as HD 40307g is much closer — located at 44 light-years from Earth.