An analysis of Alpha Centauri, which is the closest solar system to our own, has ruled out the existence of larger planets which could “endanger small, habitable worlds”.
Professor Debra Fischer, an astronomer with Yale University, said: “The universe has told us the most common types of planets are small planets, and our study shows these are exactly the ones that are most likely to be orbiting Alpha Centauri A and B.”
Alpha Centauri sits just 24.9 trillion miles away, or about 4.4 billion light-years, and is home to three stars – Centauri A, Centauri B, and Proxima Centauri.
Last year scientists revealed there was an Earth-like planet circling Proxima Centauri.
Previous models of Alpha Centauri had predicted larger planets were present in the system, but the new study led by a team of Yale astronomers has found it “almost certain to be small, rocky planets.
The team analysed data from a new wave of instruments in Chile, including the spectrograph CHIRON, which was built by Fischer's team, HARPS, and UVES, part of the Very Large Telescope Array.
According to the researchers, small, rocky planets would have gone undetected in spectrographic analysis.
This means there could be planets smaller than 50 Earth masses that were overlooked orbiting Alpha Centauri A.
There also could be eight planets smaller than Earth masses orbiting Alpha Centauri B.