CLOSEST SINGLE STAR LIKE OUR SUN MAY HAVE HABITABLE PLANET – An international team of astronomers led by the University of Hertfordshire has discovered that Tau Ceti, one of the closest and most Sun-like stars, may host five planets—with one in the star’s habitable zone.
At a distance of twelve light-years and visible with the naked eye in the evening sky, Tau Ceti is the closest single star that has the same spectral classification as our Sun. Its five planets are estimated to have masses between two and six times the mass of the Earth—making it the lowest-mass planetary system yet detected. One of the planets lies in the habitable zone of the star and has a mass around five times that of Earth, making it the smallest planet found to be orbiting in the habitable zone of any Sun-like star.
The international team of astronomers, from the UK, Chile, the USA, and Australia, combined more than six-thousand observations from three different instruments and intensively modeled the data. Using new techniques, the team has found a method to detect signals half the size previously thought possible. This greatly improves the sensitivity of searches for small planets.
Mikko Tuomi, from the University of Hertfordshire and the first author of the paper, said: “We pioneered new data modeling techniques by adding artificial signals to the data and testing our recovery of the signals with a variety of different approaches. This significantly improved our noise modeling techniques and increased our ability to find low-mass planets.”
“We chose Tau Ceti for this noise modeling study because we had thought it contained no signals. And as it is so bright and similar to our Sun, it is an ideal benchmark system to test out our methods for the detection of small planets,” commented Hugh Jones from the University of Hertfordshire.
James Jenkins, Universidad de Chile and Visiting Fellow at the University of Hertfordshire, explained: “Tau Ceti is one of our nearest cosmic neighbors and so bright that we may be able to study the atmospheres of these planets in the not-too-distant future.”
Over 800 planets have been discovered orbiting other worlds, but planets in orbit around the nearest Sun-like stars are particularly valuable. Steve Vogt from University of California Santa Cruz said: “This discovery is in keeping with our emerging view that virtually every star has planets, and that the galaxy must have many such potentially habitable Earth-sized planets. They are everywhere, even right next door!
“As we stare the night sky, it is worth contemplating that there may well be more planets out there than there are stars—some fraction of which may well be habitable,” added Chris Tinney from the University of New South Wales.