The search for extraterrestrial intelligence (SETI) has taken a new turn with two recent studies identifying unusual stars that could potentially harbor alien megastructures (2024) like Dyson Spheres. These gigantic hypothetical structures would completely surround a star to capture its energy.
In 2018, a star named KIC 8462852, nicknamed “Boyajian’s Star” or the “alien megastructure star,” caused a stir due to its unusual dimming patterns. While planetary transits can cause dimming as a planet blocks starlight from our view, Boyajian’s Star exhibited erratic dimming episodes. This led to speculation about a Dyson Sphere, but further investigation revealed dust clouds were the culprit.
Undeterred, astronomers continue the hunt for signs of advanced civilizations (Type II on the Kardashev Scale) that might build such structures. By analyzing starlight, astronomers can glean information about a star’s composition, age, and type. In the quest for Dyson Spheres, they look for two key signatures: fluctuations in brightness as the structure eclipses the star, and excess infrared radiation potentially emitted by the megastructure’s waste heat.
However, as both studies acknowledge, excess infrared light can also arise from circumstellar dust, debris disks left over from planetary formation, or protoplanetary disks surrounding young stars. While excess infrared is expected around younger stars, it diminishes as the star ages and the material coalesces into planets and asteroid belts.
The new studies identified intriguing exceptions. One study, analyzing data from nearly 5 million stars, found 53 potential candidates with unexpectedly high infrared emissions. These included stars of various ages, making them more interesting for further investigation. The other study, focused on partial Dyson Spheres, examined a catalog of 320,000 stars and identified seven with puzzling mid-infrared light surpluses.
Interestingly, these last candidates were M-dwarf stars – stars smaller than our Sun in their main sequence (stable phase of their lifespan). This is surprising because M-dwarf debris disks are exceptionally rare.
The studies emphasize that these are intriguing targets for further exploration, but the possibility of alien megastructures (2024) remains highly speculative. There are numerous natural explanations for the unusual observations. The good news is that this search can shed light on rare stellar systems while potentially revealing Dyson Sphere candidates, offering a win-win scenario.
The first study is available on the preprint server arXiv, while the second is accepted for publication in the Monthly Notices of the Royal Astronomical Society. As we explore the cosmos, these findings remind us that the universe holds many mysteries waiting to be unraveled.