Humanity's search for advanced extraterrestrial civilizations is currently being pursued in different wavelength bands using various techniques. In a recent study, a team of experts claimed to have spotted technosignatures from the Dyson spheres of an advanced civilization.
What Is a Dyson Sphere?
The Dyson sphere is a hypothetical megastructure for capturing the power output of a star. It is a concept that attempts to describe how a spacefaring civilization would meet its energy requirements once it exceeds those generated from its home planet.
Scientists believe that Dyson spheres can only be built by advanced civilizations. In this sense, the term 'advanced' refers to the kind of almost unimaginable capabilities that would enable a civilization to create a structure around an entire star.
The construction of the Dyson sphere is believed to have provided civilization with the means to harness all of a star's energy. According to experts, only a civilization that has reached Level II on the Kardashev Scale can build something massive and complex.
Search for Dyson Sphere Technosignatures
In a new study, scientists from the US, UK, India, and Sweden developed a strategy to spot Dyson sphere signatures. This collaboration is called Project Hephaistos, named after the Greek god of fire and metallurgy.
Led by Matías Suazo from Uppsala University in Sweden, the research team presented a comprehensive search for partial Dyson spheres by analyzing infrared and optical observations from Gaia, WISE, and 2MASS. The details of their study are discussed in the paper "Project Hephaistos - II. Dyson sphere candidates from Gaia DR3, 2MASS, and WISE".
The three large-scale astronomical surveys generate massive data from individual stars. The research examines the photometry of approximately 5 million sources to create a catalog of potential Dyson spheres.
The scientists tried to look for partially completed spheres that would give off excess infrared radiation. However, they are not the only objects in the universe that can do so. Many natural celestial objects, like nebulae and circumstellar dust rings, also demonstrate this ability. Additionally, background galaxies can also release excess infrared radiation and make false positives.
To identify potential Dyson sphere candidates, Suazo and colleagues developed a specialized pipeline focusing on sources that display anomalous infrared excesses. Then, the team examined the candidates further based on optical variability, H-alpha emissions, and astrometry.
From their initial list, 368 sources survived the last cut, while 328 were rejected as blends. Of these candidates, 29 were rejected as irregulars, and four were rejected as nebulars. This left seven potential Dyson spheres out of 5 million initial candidates. The research team is confident that those seven candidates are legitimate.
While the seven potential Dyson spheres are the strongest contenders, they are still candidates. There could be some reasons why they emit excess infrared, and scientists assume that it could be due to warm debris disks surrounding them.
The research team plans to conduct a follow-up optical spectroscopy to help better understand the seven sources. They aim to understand the H-alpha emission better since it originated from young disks.
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