The star τau Ceti has been the subject of a pioneering new study investigating stellar jitter, or to you and me, stellar noise. This study has improved the sensitivity of modelling techniques which enable us to detect lower mass planets orbiting stars and τau Ceti is now believed to have five planets. These planets are two to six times the mass of Earth and one resides in the habitable zone for that star. This zone is the region where a planet may retain a liquid water atmosphere under certain pressure conditions.
This star, which is a mere 12 light years away and visible to the naked eye, is our nearest neighbouring star with the same spectral classification as our Sun. The discovery of low mass planets around our nearest neighbours is intriguing. Technological improvements mean that we may be able to unravel the secrets of these planetary systems; moreover in the near future we could manage to glimpse the atmospheric composition and even search the habitable planets for signs of life.
These results came as a slight surprise when the star was initially selected by the scientific team, led by Mikko Tuomi from the University of Hertfordshire. It was believed to be a solitary star which could provide a benchmark system during sensitivity advances in the detection of planets. The presence of stellar noise in signals received from stars suggests the presence of further stars.
More than six thousand observations were combined from three different instruments and utilised in intensive modelling. This modelling adds artificial signals to the data and tests the recovery of these signals to then subtract the noise from the samples. These advances allow signals half the size to be deciphered and is very significant in the search for Earth-like planets.
