AsianScientist (Feb. 3, 2012) – A new planet that lies 22 light-years from Earth has been identified by an international team of astronomers as a likely candidate for hosting liquid water.
The planet, called GJ 667Cc, circles a relatively cool star (GJ667C), has an orbital period of 28.15 days, and a minimum mass of 4.5 times that of Earth, according to a report of the discovery to be published in The Astrophysical Journal Letters.
It receives about 90 percent of the light that the Earth receives from the Sun. But most of this incoming light is in the infrared, and so more of it will be absorbed by the planet, said Professor Chris Tinney of the University of New South Wales, a member of the team that included researchers from Chile, the U.K., the U.S., and Italy.
“This means that overall the planet absorbs about the same amount of energy from its star as the Earth absorbs from the Sun: so that would give the planet the right temperature, if it has a rocky surface and a wet atmosphere, to host liquid water,” said Prof. Tinney.
“And liquid water is seen as an essential pre-condition for the development of life,” he added.
Star GJ 667C – a member of a triple-star system – orbits a distant pair of brighter, orange K-dwarfs (GJ 667A and B).
“This discovery shows that habitable planets could form in a greater variety of environments than we previously considered,” said Dr. Simon O’Toole of the Australian Astronomical Observatory, another team member.
The planet was discovered using the “Doppler wobble” technique, which detects the slight movements of a star as its orbiting planets tug it to and fro in space.
Star GJ 667C had previously been observed to have a “super-Earth” (GJ 667Cb) with an orbital period of 7.2 days, although this finding was never published. But that orbit is too tight, and thus that planet is too hot to support life.
GJ 667C might also host a distant gas-giant planet, and an additional super-Earth with an orbital period of 75 days, but more observations are needed to confirm this, the researchers say.
Data that led to the finding came from the European Southern Observatory’s 3.6 meter telescope; one of the two 6.5 meter Magellan telescopes of the Carnegie Observatories; and one of the twin 10 meter Keck telescopes operated by the University of California and the California Institute of Technology.
The article can be found at: Anglada-Escudé G et al. (2012) A planetary system around the nearby M dwarf GJ 667C with at least one super-Earth in its habitable zone.
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Source: UNSW.
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