The "Boyajian's Star" sparked wild speculation about alien megastructures back in 2018, only to turn out to be a case of cosmic dust causing a stir. But the hunt for these hypothetical Dyson Spheres is still very much on.
Astronomers on the prowl for these alien megastructures typically rely on two key methods: looking for dips in a star's brightness as the structure passes by and searching for an excess of
However, that infrared light can also come from dusty leftovers from star formation or even super-smashing collisions between space rocks. This makes things tricky, especially when you consider most stars expected to have these discs are younger ones. That's why two new studies found something interesting: they spotted stars with excess infrared light, some older than expected!
Project Hephaistos, an international endeavour involving scientists from Sweden, India, the US and the UK, has taken a massive leap forward in this quest. After meticulously sifting through data from the European Space Agency's Gaia star map, the 2MASS infrared survey, and NASA's WISE space telescope, scientists have collectively surveyed five million distant solar systems using 'neural network' algorithms.
One of the aforementioned studies identified 53 stars with way more infrared than expected, including some older stars that become more intriguing candidates for Dyson Spheres. But before we start sending out invitations to an intergalactic potluck, these stars need further investigation to determine their exact ages and eliminate more mundane explanations (dust clouds, anyone?).
The second study focused on a different kind of Dyson Sphere — an incomplete one. They found seven M-dwarf stars (smaller, cooler stars than our Sun) with unexpected infrared signals. This is particularly interesting because M-dwarfs rarely have debris discs, which could explain the infrared.
Regardless, the implications are staggering. If these infrared excesses are indeed signatures of Dyson spheres, it wouldn't just confirm the existence of intelligent life elsewhere in the universe. It would unveil a civilisation far surpassing our own in technological prowess. The Kardashev Scale, a method for classifying civilisations based on their energy utilisation, suggests these potential alien societies have reached a Level II or higher, capable of manipulating their environment on an astronomical scale!
Alternatively, the hunt for Dyson Spheres is leading us to strange and wonderful cosmic oddities. Even if these stars don't turn out to be alien megastructures, they're helping us understand our universe better. And who knows, maybe someday we'll find that smoking gun, that undeniable proof that we're not alone. But for now, let's keep our expectations cautiously optimistic as we explore the cosmos.
The first study’s findings have been detailed in pre-print server arXiv, while the second has been accepted for publication in the Monthly Notices of the Royal Astronomical Society.