I’m delighted to see the high level of interest in Dysonian SETI shown not only by reader comments here but in the scientific community at large. I wouldn’t normally return to the topic this quickly but for the need to add a quick addendum to our discussions of Project Hephaistos, the effort (based at Uppsala University, Sweden) to do a deep dive into data from different observatories looking for evidence of Dyson spheres in the form of quirks in the infrared data suggesting strong waste heat.
Swiftly after the latest Hephaistos paper comes a significant re-examination of the seven Dyson sphere candidates that made it through that project’s filters. You’ll recall that all seven were M-dwarfs, which struck me at the time as unusual. Only seven candidates emerged from over five million stars sampled, interesting especially because the possibility of a warm debris disk seemed to be ruled out. But Tongtian Ren (Jodrell Bank Centre for Astrophysics), working with Michael Garrett and Andrew Siemion, who share an affiliation with the same institution, has other ideas.
The researchers brought in new data from the Very Large Array Sky Survey, the NRAO VLA Sky Survey and two other sources that would allow a cross-matching of the seven Hephaistos candidates with radio sources. Hephaistos had been working with Gaia data release 3 along with the findings of the Two Micron All-Sky Survey (2MASS) and results from the Wide-field Infrared Survey Explorer, which now operates as NEOWISE. The search for radio counterparts to its Dyson candidates drew hits in three cases.
This looks strongly like data contamination, and the Jodrell Bank scientists think they’ve found the sources of the infrared signatures for these three:
Candidates A and G are associated with radio sources offset approximately ∼ 5 arcseconds from their respective Gaia stellar positions. We suggest that these radio sources are most likely to be DOGs (dust-obscured galaxies) that contaminate the IR (WISE) Spectral-Energy Distributions (SEDs) of the two DS candidates. The offsets for candidate B are smaller, approximately ∼ 0.35 arcsecond. Since M-dwarfs very rarely present persistent radio emission (≤ 0.5% of the sample observed by Callingham et al. (2021)), we suspect that this radio source is also associated with a background DOG lying very close to the line-of-sight. We note that the radio source associated with G has a steep spectral index with a best fit of α = −0.52 ± 0.02 – this value is typical of synchrotron emission from a radio-loud AGN with extended jets.
Let’s untangle this. A dust-obscured galaxy is generally studied at infrared wavelengths, being too difficult a target for visible light observations. There is likely strong star formation going on here, and perhaps an AGN, or active galactic nucleus, emitting energy across the electromagnetic spectrum. Usefully a DOG with an AGN can also be examined at radio wavelengths, which can tease out information about the gas content of the galaxy. So here we have background objects that can contaminate our infrared observations and can be identified by using surveys at different wavelengths.
All seven of the Hephaistos candidates are implicated in possible contamination if we bring in the objects known as hot dust-obscured galaxies, which have inevitably achieved the acronym Hot DOGs. The authors propose that the Spectral-Energy Distributions (SEDs) of each of the Hephaistos objects are “significantly contaminated” by background galaxies of this category. If this is the case, then the oddity of finding seven Dyson sphere candidates around M-dwarfs is resolved, but it will take deeper observations of all seven to confirm this, an effort the authors believe is warranted.
Image: Here is an artist’s impression of the Hot DOG W2246-0526, based on the results of a 2016 paper by Díaz-Santos et al. (2016). In that work (not connected with today’s paper), the authors used ALMA observations to show that the interstellar medium in the Hot DOG is dominated by turbulence, and may be unstable against the energy being injected by the AGN here, potentially producing an isotropic outflow. The WISE mission was essential to finding this galaxy because the galaxy is covered in dust, obscuring its light from visible-wavelength telescopes. But the radio signature of such objects, detected by other methods, raises questions about the recent Hephaistos findings. Image credit: NASA/JPL.
Bear in mind that only 1 out of every 3,000 galaxies that WISE observed fits into this category, so we are dealing with comparatively unusual objects. But given that the Hephaistos survey ran five million objects through its pipeline, the possibility of contamination in the data in the seven proposed candidates seems worth pursuing. The hunt continues, but more and more it appears that if Dyson spheres are achievable by advanced civilizations (and if such civilizations actually exist), they are seldom built.
The paper is Tongtian Ren et al., “Background Contamination of the Project Hephaistos Dyson Spheres Candidates,” available as a preprint.
This was always the most likely outcome, but absence of evidence might not be evidence of absence. An advanced civilization could create neutrino-antineutrino pairs from pure energy, using them to carry away enough heat from the photosphere that a heat engine can generate much more than the energy required to make the neutrinos. (Early neutron stars cool predominantly by neutrinos naturally) With no more need for the star to actually shine, the builders could simply pave the outside of a yellow subgiant with an insulating layer (above the heat engines and neutrino emitters), creating a gigantic 1g space habitat – with no need for “gravity generators” to be possible. Such a habitat might still radiate visible and infrared light to space (if desired), but from a far smaller area than a Dyson sphere.
But they would need to tame the star to avoid unruly prominences from ruining their space habitat. As it happens, this very day we see this seems much more likely, because the planetary hypothesis of solar activity seems to be mathematically sound! Simulations say tiny planets at a vast distance from the Sun can exert an outright astrological influence on its 11-year cycle as Venus, Earth, and Jupiter come into alignment. https://phys.org/news/2024-05-rethinking-sun-physical-planetary-hypothesis.html If it is possible to control a star from such a distance, it is not so absurd to imagine taming one you can stand on.
Meanwhile, the solar maximum of the Sun correlates with a 0.07% increase in luminosity. Is it possible to identify such small variations in other stars, and use them to create well-informed models of the orbital parameters of their exoplanets?
The stellar Immortan Joe
https://phys.org/news/2024-05-dark-galaxy-innermost-stars-immortal.amp
https://m.youtube.com/watch?v=wWq02VnC26s
If I am not mistaken, here are the coordinates of the seven candidates in GAIA according to the table in the article :
A RACS-DR1
sky.esa.int/esasky/?target=191.303%20-26.8684&hips=2MASS+color+JHK&fov=0.08321479372026806&cooframe=J2000&sci=true&lang=en
B A RACS-DR1
sky.esa.int/esasky/?target=59.0159%20-40.5301&hips=2MASS+color+JHK&fov=0.08321479372030696&cooframe=J2000&sci=true&lang=en
G VLASS
sky.esa.int/esasky/?target=353.88693%20-0.07359&hips=2MASS+color+JHK&fov=0.0832147937203026&cooframe=J2000&sci=true&lang=en
G FIRST
sky.esa.int/esasky/?target=353.8868%20-0.0737&hips=2MASS+color+JHK&fov=0.08321479372032156&cooframe=J2000&sci=true&lang=en
G NVSS
sky.esa.int/esasky/?target=353.8844%20-0.0737&hips=2MASS+color+JHK&fov=0.08321479372031074&cooframe=J2000&sci=true&lang=en
G RACS-DR1
sky.esa.int/esasky/?target=353.8868%20-0.0737&hips=2MASS+color+JHK&fov=0.08321479372031074&cooframe=J2000&sci=true&lang=en
G TGSS
sky.esa.int/esasky/?target=353.8868%20-0.074&hips=2MASS+color+JHK&fov=0.04137245947818547&cooframe=J2000&sci=true&lang=en
Two remarks:
one of the frequencies studied is not far from the wavelength of the hydrogen; the other frequencies remain potentially wavelengths that could be exploited by a civilization that would have had substantially the same level of development as us (truck friends, don’t try to call them on 2m:)
Candidates G all have a low declination: correct me if I say a mistake but could the measurement be distorted by other objects since the observation is then made in the plane of the equator celeste?
Exciting!
Hello, Fred.
If I understand correctly, breaking the displayed data down to RA in degrees and declination in same.
RA dec Catalog name
1: 191.303 26.8684 A RACS-DR1
2: 59.0159 40.530 B A RACS-DR1
3: 353.88693 0.074 G VLASS
4: 353.8868 0.07359 G FIRST
5: 353.8844 0.0737 G NVSS
6: 353.8868 0.0737 G RACS-DR1
7: 353.8868 0.074 G TGSS
Of course, this information appears to be from some sort of telemetry stream rather than a plain to read table. And maybe I am misinterpreting it. But the surprise of it is that five of seven targets are so close together that their coordinates are hardly distinguishable from each other. The first two are separated in right ascension by about 180 and 30 degrees, plus some differences in declination ( 26 and 40 degrees). With the low declination values of the remainder, I suspect we are dealing with galactic coordinates.
If background galaxies provide some infrared, we could be dealing with one or three such objects.
On the other hand, if there is validity to the Dyson sphere hypothesis, this would represent some clustering – a “community” as it were. Were there not and the “spheres” were all over the sky, mulling that, I could suggest that thise sites were actually some sort of major league stadiums were galactic teams got together for events….
Thanks for the assist on this.
@WDK
You have to check my data. I’m not 100% sure of what is displayed in Gaia although the coordinates match (I did the test with Polaris) The proximity of the targets also intrigued me. In Gaia 3, here https://gea.esac.esa.int/archive/ you have to enter the coordinates of the objects in RA & Dec in international format ICRS in the form H:mm:sec. It is indicated “equatorial” so I suppose that it is not the galactic coordinates (?) I am also not sure of the reference time: 1950? 2014?
Here is my method: starting from the coordinates RA/DEC and the ID (J2000? ) of the seven stars given in the table I have written each one in the page of “search” of Gaia without modifying the other tabs. In the other tab “simple object search, I did the same test this time by entering the coordinates ID of the table. I have not had time to check; do not hesitate to correct me:) but the low DEC of the five stars label “G” jumps to the eyes in the table…
I have a doubt. Is it a mistake on my part or was this region of space chosen for a specific reason in which case it would be extremely surprising to find 7 stars out of 5 million in this small area that could be candidates for DS!?
Before going any further I have to check these coordinates. What is interesting in Gaia is that you can have many other information. I am not a professional astromname, you must know how to handle the database and be in the right reference system because the angular distance is extremely small. Anyway, it’s raining this morning in France => I have work:)
Fred
Well, that didn’t take long to find a natural solution to at least a few of the candidates.
But as Mike S states above (and as have others) this is not “evidence of absence”, because we may be looking for the energy signatures of our primitive heat engines, rather than some more advanced energy generation method that may have a very different signature.
Given the many popsci articles on the evidence of possible megastructures with clickbait titles, it is clear that we humans are interested in any suggestion that advanced aliens could exist. How long before technology and deep fakes make us disbelieve real evidence when it arrives, a 21st century version of the Great Moon Hoax or even Orson Welles’ 1938 radio broadcast of The War of the Worlds?
Well, so far so good. It sounds plausible that a background radiation source could provide an unusual stellar emission profile. But it is still unclear to me – and maybe others – why this phenomenon should affect seven M dwarf stars – and not other types. And it was noted that the survey results had “captures” about 200 parsecs out. Now admittedly there are more red dwarfs than just about anything else…
Could it be that their profiles are such that hotter (K or G) stars would mask that
trailing ( 2 micron) long wavelength effect? Or for it to show up, the K or G would have to be at a deeper depth in the galaxy so its IR signature would drop to a low enough level for a background dust obscured galaxy to raise any apparent discrepancy? “Dust obscured galaxies” could raise some interesting issues too, depending on where the dust was swept.
@WDK
The 2 sources must look sufficiently similar to create the apparent long wavelength emission that the Project Hephaistos algorithm would flag. [See the image in the “Seven Dyson Sphere Candidates” post.] A hotter star might well mask out the distant galaxy source, while the dimmer M_dwarf would not. As only 7 candidates out of 100 million fit the model, it doesn’t surprise me that chance allowed the match of location and spectra to occur.
The rapid resolution for 3 of the candidates suggests that the model needs further refining to eliminate these false positives due to combined sources that evaded the background filter. Interestingly, the prior excitement over Tabby’s Star was over a possible partial DS megastructure, whilst this was based on the spectrum, implying a relatively homogenous distribution of the sphere or swarm around the star depending on the length of GAIA’s observation time.
It will be interesting to see whether, or how quickly, the remaining 4 stars are shown not to have Dyson megastructures around them.
It is a pity we cannot see a millennium into the future concerning humanity’s ideas on how to power a civilization and whether the DS approach is considered as obsolete as a coal-fired power station [assuming humanity remains on a path of increasing technological capability and total economic growth]. Our descendants’ ideas in this regard might be as incomprehensible to us, as our technology would be to 10th-century Europeans living under feudalism.
Hello, A.T.
It was noted above that the investigators approached this exercise in the spirit of “what can we do to investigate the Dyson Sphere conjecture?” And the results were interesting enough. They led to more tests or conjectures.
Consequently, I had a conjecture or two myself.
On the G star conjecture, maybe I should elaborate or clarify with a simple illustrative comparison. To first order, both the main sequence M and G stars would have some gross black body characteristics. And if the M’s could have a distinctive IR signature at an apparently fixed distance, then why not another spectral type as well? And for illustration let’s take two stars to represent the properties of each with some round off. The G with a surface effective temperature of 5800 K and the M with 2900 K. And let’s say the red dwarf is about 20% of the solar radius.
For the black body luminosity ratio, the G would be about 240 x brighter.
Consequently, were we to ignore the spectral distribution of stellar flux, the
G star would have to be more than 15 x further away than the red dwarf to have about the same overall brightness.
Now if we examined the two cases more closely, the distribution over the visual and infrared would not be the same. But there is still a possible alteration of the G star’s overall signature in the IR by a background IR source. And it might be most pronounced at a given distance. And if there were a background infrared source such as a “galactic dust cloud”, then it likely would not match up exactly.
But with this first order inquiry so far, one might wonder if the phenomenon observed with red dwarfs could be duplicated with G stars 15 times farther away ( 3000 parsecs) – or with K stars at some intermediate distance. The number of M’s in the galactic neighborhood far exceeds G’s or K’s, but these can be observed over greater distances.
And at the early stage of just a few days ago though, it was not clear what we were dealing with.
Despite not having discovered any Dyson sphere civilizations, the investigators gave all of us a different perspective on the galaxy – as does the Gaia telescope mission itself.
@WDK
Thank you. I hadn’t really considered the issue of stellar distance, so I now see what you were getting at.
I can only hope the filter algorithm[s] are published with access to a database to inspect the data for each star to understand why most stars were filtered out leaving the initial 7 to remain. Perhaps this is a good case for citizen science to be engaged in looking at the data to visually determine which stars look interesting.
I kept silent on the previous posts, since I indeed waited for someone to have a second look at this.
That happened faster than what I expected.
So while I am happy to learn some now turned out to be hot-dogs located far behind, I feel some level of confidence that also the others will turn out to be ones that got line-of-sight objects that .
…but also a bit embarrassed as I am somewhat involved, Upsala is one univ that’s one of the collaborators on my current research. And a spectacular claim – to have found several alien civ’s should have been rechecked better before going public.
Hello Andrei,
again, I am not professional and I am not used to handling Gaia. Although the notations are standardized, there may be small differences in the configuration – with big consequences:) – between the Anglo-Saxon article; the IRCS standards as well as in the choice of the Gaia configuration. I’ll let the professionals check it out. Thank you, team, for all of this work.
Andrei said on May 28, 2024 at 18:20:
“And a spectacular claim – to have found several alien civ’s should have been rechecked better before going public.”
You are correct about this Andrei. However, this seems to be the pattern these days. Plus, they certainly got the publicity from this announcement. Overall, I think it is and will be a good thing for SETI science by creating awareness and expanding our paradigms.
Hello Fred and LJK!
I’m afraid you’re right that ‘insta science’ indeed have become the norm. But not always….
Some colleagues had a sensational result a few years back, and when told beforehand by one of the professors, since I was marginally involved in the matter. I thought for a moment and replied: ‘That cannot be right.’
And he replied: “That’s why we’re rechecking it for a fourth time now before publishing.”
They did recheck for potential errors or contaminated data, and could not find any. And so far no one have challenged it. And this is what I consider good science.
But yes, while some exposure can be good. We also need to consider how this also trigger the madcaps, who make wild and incorrect statements online.
And I fully agree we should keep looking, though what we’re trying to find is likely to be a very rare bird indeed.
What I honestly hope to see in my lifetime is the unequivocal announcement of a life bearing planet. Such would in my estimate be comparably more common, even if one such would hold only microbes or perhaps very basic organisms.
And that might be one announcement that would have me jump over to exobiology, to try to figure out how old that life is as well as the world it is found on.
One such might even be found nearby, while I am sceptical about some of the Earth sized planets near M-stars, I got some hope for the very quiet Teegarden’s Star that got 3 known planets and this year got two more candidates which bring the number of planets in the habitable zone to 3.
See fig 6 in the PDF linked below.
https://arxiv.org/pdf/2402.00923
We are learning. Searching for ETI in its various possible forms is just starting to emerge from its early stages, when most of the folks who conducted this effort were looking for deliberately aimed radio signals designed to get our attention.
It has only been a few decades that SETI switched to Optical SETI after even more decades of rejecting the idea of lasers and infrared transmissions as a possible sign of intelligent life out there.
So whatever the case is with this current search, it should be seen as how science progresses. We are trying to find others in a realm vaster and more populated than our current evolution prepared us for.
That we can conceive of beings on other worlds in a non-supernatural fashion is impressive enough. Now we are trying to find them and with rather limited resources and tools. At least we are doing it. We just need to ramp up our efforts and search parameters. The Dyson Shells are a good start.
SET is finally being allowed out of its crib and that is how we are going to succeed.
I always found the target choice somewhat paradoxical. Why look at sunlike stars and especially red dwarfs? Well, they provide a long-lasting and calm environment. But if a civilization continues to be expansive until KII stage, why it should turn to seeking longevity just at this point? Naturally, if it was energy-, matter- and space-hungry all the way through, it will remain the same. Then, it would seek matter- and energy-rich environments, and this would be OB stars and compact objects.
At KII stage, it takes not much effort to migrate from homeworld into an open cluster, at least for a fraction that desires to continue expansion. There, it would obtain resources that are orders of magnitude richer than in their home system. Massive stars live fast and die young, but hey, it’s still millions of years, much longer than travel time.
Orange and red dwarfs make good gravitational lenses to build a communication hub around them, but stellar remnants are much better, and they could be found in open clusters as well.
Of course, Dysonian SETI is much more complicated here because OB stars often have dusty environment, but the power throughput, and thus visibility, is many order of magnitudes higher than it would be around ordinary stars. Anyone searched the depths of Orion, or the Homunculus nebula, for radio emission, ultra-narrow laser lines and ultra-fast transients? :-)
The links I posted above that point to anything. I don’t know why. Sorry.
You have to go to Gaia Archive here https://gea.esac.esa.int/archive/
then
– choose the “single object” tab at the top left (few seconds to display the tab)
– delete the coordinates details displayed by default in this tab
– enter the coordinates of the candidate stars by copying the ID of each object, given in the table of the article. (copy and paste in “J+RA+DEC”)*
– keyboard “enter” key or mouse click.
Gaia normally displays the object in the right window after a few seconds.
* The coordinates are displayed by hovering over this window with the mouse.
In this window you can copy the link of the URL (4th icon from the right, top right) The image is enlarged in ESA-Sky.
We see that the A&B objects are not in the same place on the celeste sphere but that the lable G are.
Apologies for polishing my apple but may I remind readers of the “Dyson Shutter” I wrote about some years ago. A spectacular object with almost 360 degree intergalactic signaling capability.
Paul, I’m still at work on another article!
https://www.centauri-dreams.org/?s=citizen+SETI
Good! Keep at it, Scott, and send along when ready.
Hello Scott
I read your article with great pleasure, especially because I was a radio amateur (I no longer practice).
Could you send us ACD (the link is empty) I wish I could run it on Linux-ubuntu. I don’t have a mathematical mind but rather creative, I like this kind of modeling. I’ve never been able to get “Grabby alien”* to work, which has the same idea but your model is more interesting because it introduces the end of the radio broadcast of a civilization which gives this diagram in rings. I would come back because it’s exciting…
Fred
*https://www.centauri-dreams.org/2022/05/20/if-loud-aliens-explain-human-earliness-quiet-aliens-are-also-rare-a-review/
Bean counting a Dyson Shell project…
https://arstechnica.com/science/2023/03/building-a-dyson-sphere-whats-the-payback-time-of-disassembling-a-planet/?utm_source=facebook&utm_medium=social&utm_campaign=dhfacebook&utm_content=null
If a more distant galactic source contaminates the spectral data, would this not be evident from the spectra due to the red-shifted absorption lines that add to the main star’s apparent spectral absorption lines?
Dyson Spheres in the Milky Way?
by Annelia Anderson | Jun 4, 2024 | Daily Paper Summaries | 0 comments
Title: Project Hephaistos – II. Dyson sphere candidates from Gaia DR3, 2MASS, and WISE
Authors: Matías Suazo, Erik Zackrisson, Priyatam K. Mahto, Fabian Lundell, Carl Nettelblad, Andreas J. Korn, Jason T. Wright, Suman Majumdar
First Author’s Institution: Observational Astrophysics, Department of Physics and Astronomy, Uppsala University, Sweden
Status: Published in Monthly Notices of the Royal Astronomical Society [open access]
Civilizations of the Future
As civilizations progress, so does their need for greater sources of energy. Such is the simple but sound concept that drove astronomer Nikolai Kardashev to formulate his hypothetical classification of advanced civilizations based on the amount of energy they are able to control.
Presented in 1964, the Kardashev scale proposes three stages: Type I: civilizations that utilize all available energy from their planet; Type II: civilizations that draw energy directly from their star; and Type III: civilizations that tap the energy of their entire galaxy. (Further stages are commonly accepted today and place our own civilization at Type 0.7, as we have not harnessed the full potential of our planet’s energy.)
In 1960, a similar minded physicist Freeman Dyson imagined that a futuristic civilization, with technology requiring more energy than their planet could provide, would create some sort of spherical structure around their host star to mine more of its energy, now called a Dyson sphere.
Furthermore, he realized that if such a “Type II” civilization exists, we would be able to detect the waste-heat emission of their Dyson sphere as an excess of infrared (IR) radiation from the star it surrounds. Thus began the search for Dysonian technosignatures of advanced extraterrestrial life.
Project Hephaistos (appropriately named for the Greek god of blacksmiths and fire) heeds Dyson’s suggestion, with the help of modern observations and analysis. In 2018, their search for nearly complete Dyson spheres which dim the observed light of the star unfortunately left them empty-handed. But remarkably, in today’s paper their search for partial Dyson spheres, which only partially obscure the star’s light, has revealed seven candidates within the Milky Way!
Full article here, plus a new image of a Dyson Shell under construction:
https://astrobites.org/2024/06/04/dyson-spheres-in-the-milky-way/
As we are increasingly becoming aware, biological humans are connected to the terrestrial biosphere. If we are effectively anchored to Earth except for short forays into space, there is no reason to build a Dyson sphere for our terrestrial needs (Unless melting the planet is the absurd goal). Therefore, the idea of living inside the sphere for lebensraum is not really going to work with a very long time to recreate the terrestrial biosphere inside it. A Dyson swarm of O’Neill-type habitats makes more sense, if, a big if, we solve the technological issues of being terrestrial biospheres in a bottle. If we want just purely the energy collection, the sphere must have a gap for our planet or be built outside our orbit and the energy used for non-terrestrial purposes – e.g. build a Matrioshka Brain or other energy demanding goals.
For a Dyson Sphere, it seems to me, that the only inhabitants would be artificial – machines and robots as they do not require a biosphere, just a technosphere.
If this logic is correct, then if we do detect such a structure, it will not be filled with biological beings (except as temporary visitors) but be almost entirely like a machine with a robotic civilization.
Finding a Dyson sphere could be our first contact with alien life
BY MARK R. WHITTINGTON, OPINION CONTRIBUTOR –
06/02/24 9:30 AM ET
https://thehill.com/opinion/technology/4696800-finding-a-dyson-sphere-could-be-our-first-contact-with-alien-life/
‘Dyson spheres’ were theorized as a way to detect alien life. Scientists say they’ve found potential evidence
Story by Jacopo Prisco, CNN • 1h •
https://www.msn.com/en-us/news/technology/dyson-spheres-were-theorized-as-a-way-to-detect-alien-life-scientists-say-they-ve-found-potential-evidence/ar-BB1o9FIa?rc=1&ocid=winp1taskbar&cvid=1b104791faeb4125923acbe3bf18dcb9&ei=4
The article above focuses on the need to take Jupiter apart to make a Dyson Shell. Robert Bradbury said it could be done with Mercury, which would be much easier in comparison.
People are still focusing on the original methods and uses for Dyson Shells rather than the new concepts which make even more sense to build them. How long before the media ever catches up with this?