JWST Just Examined Two Stars Suspected of Harboring Dyson Spheres

"Fnord666" writes:

JWST Just Examined Two Stars Suspected of Harboring Dyson Spheres. Here's What It Found...:

Somewhere in the Universe, an alien culture may have developed the technology to build giant megastructures around stars, harnessing their energy on an unimaginable scale.

First proposed in 1960 by theoretical physicist Freeman Dyson , the Dyson sphere has become one of the most enduring symbols of the search for extraterrestrial intelligence.

This is because such structures should change starlight in ways we can detect from Earth - telltale technosignatures that could finally reveal an advanced alien civilization.

Now, astronomers have used the JWST 's golden infrared eye to put two of the strongest Dyson sphere candidates to the test.

"Waste heat. That is the whole game," astrophysicist Olivia Curtis of Pennsylvania State University, co-author of a preprint describing the analysis , told ScienceAlert.

"A civilization can hide its star behind a shell of solar collectors, but thermodynamics always collects its tax, and all that captured starlight has to come back out as a warm mid-infrared glow."

That glow would be unavoidable. Just as a laptop or lightbulb gives off waste heat, so too would any machine that harvests a star's energy. The larger the hypothetical megastructure, the brighter that excess infrared radiation should become.

That excess is exactly what Project Hephaistos , led by astrophysicist Erik Zackrisson of Uppsala University in Sweden, set out to find. Even false positives could teach us how to better search for alien tech - by revealing the many ways the Universe can mimic it.

The search sifted through roughly five million Milky Way stars looking for exactly this kind of infrared excess - more mid-infrared light than an ordinary star should produce.

Seven stars survived the team's increasingly stringent tests, with the two studied here emerging as the search's most compelling candidates.

JWST quickly exposed the two candidates as Dyson sphere impostors - and the explanation was brilliantly simple. The light from both stars was being boosted by a distant galaxy almost perfectly lined up behind them.

"The first images did it," Curtis said.

"At the shortest wavelength you mostly see the star, and as you step out to 10 and then 15 microns the star fades away while a second source right next door lights up. The moment you see two sources where WISE saw one, you know the star was never the thing glowing, and the spectra only confirmed what the pictures had already given away."

These weren't just any background galaxies. Both are exceptionally bright in infrared light, exactly the wavelengths astronomers search when hunting for the waste heat of a hypothetical Dyson sphere.

One, sitting behind Candidate D, appears to be a Hot Dust-Obscured Galaxy, or Hot DOG, whose central supermassive black hole is heating vast clouds of dust.

The other, behind Candidate E, is likely a dusty starburst galaxy, where stars are forming at a furious rate.

Both galaxies naturally produce the kind of warm infrared glow astronomers were searching for.

Read more of this story at SoylentNews.