St Albans astronomers discover Earth-like planet

John Barnes, at the University of Hertfordshire has been working on a project centred on Tau Ceti, o

John Barnes, at the University of Hertfordshire has been working on a project centred on Tau Ceti, one of the closest and most Sun-like stars 12 light-years from Earth. - Credit: Archant

AN INTERNATIONAL team of astronomers including several from St Albans have discovered that one of Earth’s closest and most Sun-like stars may host five planets, with one in the star’s habitable zone.

Mikko Tuomi and Hugh Jones, both of St Albans, along with John Barnes, from Sandridge, have been studying star Tau Ceti as part of the University of Hertfordshire-led project.

Tau Ceti, the closest single star that has the same spectral classification as our Sun, is 12 light years away and visible to the naked eye at night.

John, an astrophysicist, said the international team of astronomers from the UK, Chile, the USA and Australia had combined more than 6,000 observations from three powerful telescopes.

The researchers had intensively modelled data from those instruments, based in Chile, Australia and Hawaii.


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Aside from discovering that Tau Ceti might host five planets, the team estimated that those planets had a mass between two and six times that of 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 such a zone of any Sun-like star.

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Mikko, from the university and the first author of the study’s paper explained: “We pioneered new data modelling 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 modelling techniques and increased our ability to find low-mass planets.”

He added that Tau Ceti was chosen for a noise modelling study because it was assumed it contained no signals.

Hugh explained: “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.”

Tau Ceti is one of Earth’s nearest cosmic neighbours and so bright that researchers hope the atmospheres of its planets can eventually be studied.

John said that he became interested in astronomy after looking at the night sky from his family’s Yorkshire farm when young, and joined a local astronomical society.

He added: “I remember looking at stars while lying on fields. That inspired me and I decided to study that side of science.”

Research into Tau Ceti will continue, with John saying that one of those five planets could potentially be found to support liquid.

Chris Tinney, from the University of New South Wales, said: “As we stare at 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.”

The team’s finding comes just two months after Mikko announced he and other local astronomers, including Hugh, had discovered a new super-Earth planet that may have a similar climate to Earth and be perfect to support life.

This new super-Earth, HD 40307g, is located 42 light years from Earth, and is part of a six-planet system.

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