The basic idea is simple: an advanced civilization would want to capture as much of its star's energy as possible. Rather than building one impossibly large shell around a star, scientists now think the most realistic version would be a "swarm"—thousands or millions of individual solar collectors orbiting together, soaking up nearly all the star's light.
The question has always been: if something like that actually exists out there, what would it look like through a telescope? Amirnezam Amiri, a researcher at the University of Arkansas, set out to answer exactly that. His study, soon to be published in the journal Universe, narrows down where to look and what to look for.
The Best Stars to Search Are the Smallest Ones
It turns out that the most promising targets aren't bright, Sun-like stars. They're the dim, unassuming ones—red dwarfs and white dwarfs.
Red dwarfs are the most common stars in the Milky Way. They're small, cool, and incredibly long-lived, burning their fuel so slowly that they can last for trillions of years. From an engineering standpoint, their smaller size is a major advantage. A Dyson swarm around a red dwarf could orbit much closer to the star—between 0.05 and 0.3 astronomical units—meaning it would require a fraction of the building material needed for a larger star.
White dwarfs may be even better candidates. These are the dense, Earth-sized remnants left behind after Sun-like stars run out of fuel and collapse. Because they're so compact, a swarm could orbit just a few million kilometers above the surface. They also release energy at a steady, predictable rate for billions of years—essentially a reliable, long-term battery for any civilization lucky enough to live near one.
A Star That Glows in the Wrong Color
Astronomers organize stars on a chart called the Hertzsprung-Russell diagram, which plots temperature against brightness. A Dyson swarm would push a star into a part of this chart where no natural star should exist.
Here's why: the swarm would absorb almost all of the star's visible light and convert it into usable energy. But energy can't just vanish. The waste heat from all that activity would be radiated outward as infrared radiation—invisible to the naked eye but detectable with the right instruments.
The star's total energy output would stay the same, but its apparent temperature would plummet. A typical red dwarf sits around 3,000 Kelvin. A Dyson swarm surrounding it could register as cold as 50 Kelvin—roughly a hundred times colder. That's a region of the diagram that is completely empty in nature. Anything found there would immediately stand out.
A Clean Signal With No Dust
There's another telltale sign. Ordinary stars surrounded by debris often show silicate emissions—a spectral fingerprint of cosmic dust. A Dyson swarm, on the other hand, would be made of structured radiator panels, not loose particles. The result would be an unusually "clean" infrared signal with none of the messy dust signatures astronomers normally expect around stars with orbiting material.
Strange Flickering Could Be the Final Clue
A fully solid Dyson sphere is almost certainly impossible to build—the engineering requirements are simply too extreme. A swarm, however, would have gaps between its components. As those individual collectors orbit the star, they would cause the star's brightness to dip and shift in ways that no natural phenomenon would produce. These wouldn't be the smooth, regular dimming patterns caused by passing planets. They'd be irregular, complex, and clearly artificial—light curves that don't match anything in our existing catalogs.
We're Already Looking
The James Webb Space Telescope is ideally suited for this kind of search because it was designed specifically to observe in infrared. Older missions like WISE have also contributed data. In fact, in May 2024, a project called Hephaistos identified seven promising Dyson sphere candidates—all orbiting red dwarfs—after scanning roughly 5 million stars. One was later ruled out when a background supermassive black hole explained the signal. That leaves five candidates still worth investigating.
None have been confirmed as alien structures, and they may all turn out to be natural phenomena we don't fully understand yet. But Amiri's work gives astronomers a sharper set of tools to tell the difference. If a Dyson swarm is out there somewhere in the Milky Way, the infrared fingerprints it leaves behind may finally lead us to it.