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Astronomers identify five potential planets orbiting Tau Ceti
Posted: Fri, Dec 21, 2012, 10:33 AM ET (1533 GMT)
Tau Ceti exoplanets illustration (J. Pinfield/RoPACS) Astronomers announced this week the discovery of up to five extrasolar planets orbiting the nearby star Tau Ceti, including one that is potentially habitable. Astronomers identified the five planets in radial velocity observations of the star taken at the European Southern Observatory in Chile as well as at the Anglo-Australian Telescope in Australia and the Keck Observatory in Hawaii. The five planets have orbital periods ranging from 14 to 640 days and masses of 2 to 6.6 times that of the Earth. One planet, with a minimum mass of 4.3 times the Earth and a period of 168 days, lies in the star's habitable zone; some argue the the outermost planet may also be habitable. Tau Ceti is a Sun-like star about 12 light-years from the Earth. Some astronomers are skeptical of the finding, noting that the periodic shifts seen in spectral features could be explained by stellar activity or may be noise.
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