This is no sci-fi film.
Scientists say they may have discovered evidence of alien life – in the form of enormous Dyson spheres.
Dyson spheres are hypothesised structures that surround entire stars to absorb their energy – a way in which advanced aliens could draw huge amounts of power.
If such objects exist, they should give off a detectable infrared glow – also known as a technosignature.
Now, after combing through mountains of space data, astronomers think they may have found not one, but seven.
In a collaboration known as Project Hephaistos, teams of astronomers from Uppsala University in Sweden and the International School for Advanced Studies in Italy combined data from the European Space Agency’s Gaia satellite, the 2MASS sky survey and Nasa’s Wise satellite.
Each team separately analysed the same five million stars from the combined datasets and found the same signs of excess infrared heat that could not be explained by known natural processes.
To do this, the teams constructed a pipeline, where they filtered out certain factors to whittle down the sample of five million objects.
The filters focus on detecting sources that display infrared excesses that cannot be attributed to any known source of radiation.
Dr Matías Suazo of Uppsala University and his team spotted strange signals from seven red dwarfs within 900 light-years of Earth, which appeared to be around 60 times brighter in infrared than expected.
‘All of these objects are M-dwarfs, for which astrophysical phenomena cannot easily account for the observed infrared excess emission,’ the researchers wrote.
Up to 16% of each star would have to be covered to account for the signal. If it was aliens, the signals would be more likely something known as a Dyson swarm – a collection of large satellites orbiting a star to collect energy.
The term was coined by physicist and mathematician Freeman Dyson in 1960, after he was inspired by the 1937 science fiction novel Star Maker by Olaf Stapledon.
The spheres are a hypothetical megastructure that surrounds a star and captures a large amount of its solar power output.
The idea is that the energy collectors would absorb and re-radiate energy from the star, making its appear unusual to far-off observers – and helping prove the existence of an advanced civilisation.
Results from the International School for Advanced Studies in Italy found a broader range with 53 candidates among larger stars, including some Sun-like stars at distances of up to 6,500 light-years from Earth.
However, there are some mundane reasons why infrared signatures are being emitted from certain stars.
One natural explanation is that the stars are surrounded by hot, planet-forming debris disks – but the researchers say that the stars they found appear too old to do this.
‘None of them clearly explains such a phenomenon in the candidates, especially given that all are M dwarfs,’ the researchers wrote.
Another possibility is that each star could be positioned in front of a distant galaxy, which is giving off an infrared glow.
Either way, they say that a follow-up spectroscopy would help reveal the sources better, and it might just reveal where aliens are in our galaxy.
The results are published in the Monthly Notices of the Royal Academy of Sciences.
