Some of the most promising locations to search for possible alien megastructures, known as Dyson spheres, may not be stars like the Sun, but rather the galaxy’s smallest and dimmest stars.
Physicist Freeman Dyson introduced the idea of a Dyson sphere in 1960, describing it as a shell or, more realistically, a swarm of orbiting collectors that could capture most of a star’s energy. This concept has interested scientists searching for signs of advanced technology, but the question of how such a structure would appear in astronomical observations remained unknown.
Now, a new study, available on the arXiv preprint server, suggests that one of the coldest objects in a stellar system could, in principle, be an artificial megastructure rather than a natural astronomical object.
Amirnezam Amiri, a physicist at the University of Arkansas, explored the question of Dyson spheres by modeling these hypothetical megastructures around two often-overlooked types of stars: red M-dwarfs and white dwarfs. Amiri credits discussions with Harvard astronomer and founder of the Galileo Project, Avi Loeb, with helping shape the study.
Small, Dim, and Built to Last
Red dwarfs make up about 70% of the stars in the Milky Way. These stars burn slowly and can remain stable for trillions of years, much longer than the universe has even existed so far. White dwarfs offer a different benefit. As the dense remnants of stars like the Sun, they shrink to about 1% of their original size. This means a Dyson swarm could orbit much closer, requiring less material and a smaller structure than one built around a star like the Sun.
Amiri’s study explores how astronomers could detect such structures. Both red dwarfs and white dwarfs are dim enough that the infrared heat emitted by a Dyson swarm would stand out more clearly against the star’s own light.
Reading the Wreckage on a Star Chart
Astronomers use the Hertzsprung-Russell diagram to classify stars by temperature and brightness, and this tool is central to Amiri’s analysis. A Dyson swarm would not destroy a star’s energy, but would capture its light and re-emit it as heat at much longer wavelengths.
In the new model, a star with a Dyson swarm would appear on the H-R diagram at the same luminosity but shifted dramatically toward the cool end. For instance, a red dwarf at about 3,000 K could appear surrounded by a shell as cold as 50 K, a difference of about two orders of magnitude. No known stars naturally occupy this region of the H-R diagram.
Identifying Factors
Dust and distant galaxies can also produce strong infrared emissions, so astronomers cannot identify a Dyson swarm using temperature alone. Amiri’s model points to a more complex set of clues. A true Dyson swarm would not show the silicate dust features seen in normal dusty disks, so its spectrum would be unusually smooth for an object with strong infrared emission.
Additionally, if the swarm consists of many separate collectors rather than a solid shell, there would be gaps that cause irregular, non-stellar flickering as the pieces move. Each of these signs can have natural causes, but finding them together is rare and hard to explain without considering artificial structures.
Future Observations
Astronomers can carry out this search using existing telescopes. The James Webb Space Telescope’s infrared instruments are already designed to detect faint, cold signals like these. The Vera C. Rubin Observatory’s new sky survey and the Nancy Grace Roman Space Telescope, which is expected to launch later this year, will add to these efforts. Together, they will generate the kinds of observations needed to search for the signatures described in the study.
Possible candidates for these future observations have already been identified. In 2024, Project Hephaistos identified seven potential Dyson sphere candidates among about 5 million cataloged stars, all linked to red dwarfs. One was ruled out after it was shown that a background black hole caused the observed signal. Several candidate Dyson sphere systems still remain under investigation. Amiri does not claim that any of these are actual Dyson spheres, and the paper makes this clear. Instead, the study offers a better way to tell true anomalies apart from dusty disks before using valuable telescope time. If a Dyson swarm surrounds a star and reradiates its energy at temperatures unlike those of natural stars, upcoming infrared surveys may finally be able to detect one.
Austin Burgess is a writer and researcher with a background in sales, marketing, and data analytics. He holds an MBA, a Bachelor of Science in Business Administration, and a data analytics certification. His work focuses on breaking scientific developments, with an emphasis on emerging biology, cognitive neuroscience, and archaeological discoveries.