Astronomers have spotted a planet they call a "super-Earth" about 42 light years away that could have liquid water and an atmosphere stable enough to support life as we know it.
The new super-Earth planet sits in the habitable zone of a nearby star known as HD 40307, and is part of a six-planet system that was previously thought to contain three planets in orbits too close to the star to support liquid water. A new developed software package that is able to process the signals more thoroughly reveal the presence of the three additional planets. The astronomy team, including Carnegie co-author Paul Butler, Mikko Tuomi of the University of Hertfordshire and Guillem Anglada-Escudé of the University of Göttingen , reanalyzed spectra taken with the HARPS spectrograph through the European Southern Observatory public archive.
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 known as HD 40307, making it into a six-planet system."
The planet outermost orbit from the star has raised the astronomers' interest the most. It has a mass at least seven times of the 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 night-time effect on the planet which would be better at creating an Earth-like environment," he astronomers 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," said Anglada-Escudé.
The team noted that NASA's Kepler spacecraft found a planet with a similar orbit earlier this year but said that planet, known as Kepler 22d is 600 light years from Earth.
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