If there are Dyson spheres around white dwarfs, we should be able to detect them

Artistic representation of a Dyson sphere. Credit: Kevin McGill

The search for Dyson spheres, rings or swarms remains a concern for many astronomers. If there are, they will eventually be found, and the person or research team that does so will go down in history for making one of the most important discoveries in human history. If you’re interested in claiming this accolade for yourself, a great place to look may be around white dwarfs. At least that’s the theory put forward in a new paper by Benjamin Zuckerman, a retired UCLA professor of astrophysics.

Dyson spheres belong to very advanced civilizations, generally thought of as artificial spheres surrounding an entire star. However, if they are actually constructed, they are more likely to appear as a partially completed sphere, or even a ring or “swarm” of small habitats that encompass their host star. Collectively called DSR by Dr. Zuckerman, each of these configurations would have a unique and telling sign: they would alter the infrared signature of that star.

This is the subject of Dr. Zuckerman’s work. His theory centers on scanning white dwarfs for anomalous infrared signatures that might indicate an artificial construct surrounds them. But why white dwarfs? In addition to being reasonably ubiquitous, they have the distinction of being the end state of stars like ours.

The life cycle of a solar-mass object would go through the main sequence, like we’re in now, and then back up into a red giant phase, potentially gobbling up many of the planets the system has accumulated in the meantime. It would then basically collapse into a white dwarf, where it has existed for billions of years before potentially degenerating into a low-power black dwarf.

UT video discussing Dyson spheres.

While white dwarfs are still alive, they emit thermal radiation up to a few thousand degrees Kelvin, which could potentially be absorbed and reappropriated to power a DSR. However, as Dr. Zuckerman points out, this star would need to have developed a technological civilization before such an object was built around it, because any civilization capable of creating a RSD is probably not interested in one. build one around a particular white dwarf. than the one around which they grew up.

Zuckerman’s earlier work points to the possibility that if there are, in fact, technologically advanced civilizations in the Milky Way, at least some of them would have seen their host star turn into a white dwarf. If their response to this potentially cataclysmic event is to build a DSR around their now more stable star, then we should be able to see them using our new infrared telescopes.

In fact, there have been observation campaigns at WISE and at Spitzer. They both observed white dwarfs with masses around what we would expect our own sun to transform into. They even noticed a few incidences of anomalous infrared signatures. However, researchers believed that dust was the most likely cause of these anomalies, and there was no evidence of DSR.

UT video discussing DSR detection

There has never been evidence of a DSR in astronomical data, however, much to the chagrin of alien hunters. But the absence of evidence is not evidence of absence – it just helps limit the likelihood. According to Dr. Zuckerman, with the observations we have already made, we can make a statistical calculation that less than 3% of habitable planets that orbit stars that eventually turn into white dwarfs build a RSD around them. . Admittedly, current estimates put the number of habitable planets around G-type stars at 300 million likely to evolve into white dwarfs. So there could still be over 9 million civilizations that have built a DSR around their white dwarf star.

But for now, the Fermi Paradox still holds, and science continues to collect data that will further limit estimates of the number of advanced technological civilizations in our galaxy or prove that we are not alone once and for all. Either way, the more advanced infrared telescopes, like JWST, which are slowly coming online, are one of our best ways to find them. And there will always be people who want to keep looking.

Planetary remnants around white dwarf stars

More information:
B Zuckerman, Infrared and optical detectability from Dyson spheres to white dwarf stars, Royal Astronomical Society Monthly Notices (2022). DOI: 10.1093/mnras/stac1113

B. Zuckerman et al, Characterization of planetary material chemistry around white dwarf stars, Handbook of exoplanets (2017). DOI: 10.1007/978-3-319-30648-3_14-1

B. Zuckerman et al, Excessive infrared radiation from a white dwarf – an orbiting brown dwarf?, Nature (2003). DOI: 10.1038/330138a0

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