Two potentially habitable ‘super Earths’ are spotted orbiting a sun-like star that is so close to our planet it can be seen with the naked eye
Also known as the ‘Goldilocks zone’, this is the orbital region that is neither to hot nor too cold to allow liquid surface water and, potentially, life.
The new discovery is a continuation of previous research into the star system, in which scientists detected five planets orbiting the star, labelled tau Ceti b to f.
The new study, which included experts at the University of Hertfordshire, confirmed the existence of tau Ceti e and f and found two new planets, called tau Ceti g and h.
The three planets b, c and d claimed in the previous study were not detected in the latest set of data.
The four planets identified have masses as low as 1.7 Earth mass, making them the smallest planets ever detected around the sun-like stars at such wide orbits.
Previous research suggested that planets e and f were too large to be rocky and hence were unlikely to have the atmosphere needed to host alien life.
The new study found that e and f have masses 3.9 times that of Earth, which the researchers say means it could support life after
Sophisticated modelling techniques using data from thousands of observations allowed the team to detect tiny signals generated by the gravitational tugs on tau Ceti from the ‘Super Earth’ orbiting planets.
Star movements of 10 cm/s (4″/s) are the upper limit required for detecting an Earth ‘analog’ – a planet or moon with environmental conditions similar to those found on the planet Earth.
Dr Fabo Feng, an astronomer at the University of Hertfordshire and lead researcher on the study, said: ‘We’re getting tantalisingly close to observing the correct limits required for detecting Earth-like planets.
‘Our detection of such weak wobbles is a milestone in the search for Earth analogs and the understanding of the Earth’s habitability through comparison with these.’
Sun-like stars are thought to be the best targets for searching for habitable worlds Earth-sized planets, due to their similarity to our own star.
Tau Ceti is very similar to the sun in its size and brightness, and they both host multi-planet systems.