I’ve mentioned before that I think the name ‘Tabby’s Star’ is a wonderful addition to the catalog. It trips off the tongue so much more easily than the tongue-twisting KIC 8462852, and of course it honors the person who brought this unusual object to our attention, Yale University postdoc Tabetha Boyajian. 1480 light years away, Tabby’s Star is an F3 with a difference. It produces light curves showing objects transiting across its face, some of them quite large, and the search is on to find an explanation that fits within the realm of natural causes.
Five articles about Tabby’s Star have already appeared in these pages, with the most likely explanation being some kind of cometary activity, an answer that seems to satisfy no one. We’ve also consulted both Boyajian’s paper on the subject and a paper by Jason Wright and colleagues out of the Glimpsing Heat from Alien Technologies project at Penn State. The light curves we’re looking at do fit the scenario of a ‘Dyson swarm,’ a cluster of power-collecting surfaces that an advanced civilization might create to extract maximum energy from its star.
Thus we can’t rule out the possibility of an extraterrestrial civilization, but no one is claiming that we’ve found one. The point is that in terms of Dysonian SETI, which looks for signs of another civilization’s activity in our astronomical data, Tabby’s Star is the most interesting target we’ve found, so it only makes sense to investigate it. Assuming we do deduce a natural cause for its signature, we will have learned something about an unusual astrophysical process, and that is all to the good. The sole driver here is to investigate and find out what is happening.
The SETI Institute has a natural interest in all this and has been deploying the Allen Telescope Array on Tabby’s Star for more than two weeks. Now we have an update on what the Institute has found. The effort used the Array’s 42 antennas north of San Francisco to look for narrow-band signals (approximately 1 Hz in width) that could be part of an interstellar beacon. In general, SETI at radio and optical frequencies (SETI, that is, of the non-Dysonian kind) looks for this kind of signal, a deliberate attempt by a civilization to declare its presence.
Image: Allen Telescope Array. Credit: Seth Shostak, SETI Institute.
But the SETI Institute also looked for broadband signals, an interesting choice. Here we are asking whether, if there really is an enormous astro-engineering effort going on around this star, there would be spacecraft sent out to service it. Our own investigations into quick travel around the Solar System point to microwave beaming as a feasible solution, the basis for an interplanetary infrastructure. Such intense microwave beams might well be visible, a kind of ‘leakage’ from the civilization’s activities that implies nothing about communication.
Here’s the result, from the SETI Institute’s paper on the work (Jy stands for jansky, a unit of density used in radio astronomy):
The observations presented here indicate no evidence for persistent technology-related signals in the microwave frequency range 1 – 10 GHz with threshold sensitivities of 180 – 300 Jy in a 1 Hz channel for signals with 0.01 – 100 Hz bandwidth, and 100 Jy in a 100 kHz channel from 0.1 – 100 MHz.
So no clear evidence for either kind of signal between 1 and 10 GHz. The paper goes on:
These limits correspond to isotropic radio transmitter powers of 4 – 7 1015 W and 1020 W for the narrowband and moderate band observations. These can be compared with Earth’s strongest transmitters, including the Arecibo Observatory’s planetary radar (2 1013 W EIRP [effective isotropically radiated power]). Clearly, the energy demands for a detectable signal from KIC 8462852 are far higher than this terrestrial example (largely as a consequence of the distance of this star).
What this initial search does is to place upper limits on anomalous emissions from Tabby’s Star. It tells us that we can rule out omnidirectional transmitters broadcasting narrow-band signals at approximately 100 times today’s total terrestrial energy usage, as well as broadband emissions of ten million times terrestrial energy usage. These numbers are high, as the Institute notes, but the paper goes on to say that required transmitter power for narrow-band signals could be reduced considerably if a signal were being beamed in our direction intentionally. It’s worth remembering, too, that any civilization of K2 status (capable of building a Dyson swarm) should have approximately 1027 watts to work with, the energy output of its star.
In any case, says Institute astronomer Seth Shostak, we keep looking:
“The history of astronomy tells us that every time we thought we had found a phenomenon due to the activities of extraterrestrials, we were wrong. But although it’s quite likely that this star’s strange behavior is due to nature, not aliens, it’s only prudent to check such things out.”
Exactly so. The authors add that the star will be the subject of observations for years to come.
Addendum: The Boquete Optical SETI Observatory in Panama is also going to be brought into the search, as per this story.
The paper is Harp et al., “Radio SETI Observations of the Anomalous Star KIC 8462852” (preprint). A SETI Institute news release is also available.
I stood on the beach and stared at the ocean for ten minutes. I did not see any fish swimming in that big body of water, therefore no fish must exist in the ocean.
That is how I feel about this (and most other) SETI efforts, irregardless of whether or not KIC 8675309 has aliens building big structures around it.
https://centauri-dreams.org/?p=27889
http://www.daviddarling.info/encyclopedia/S/SETI_critical_history_cover.html
Microwaves are not an interesting wavelength for power beaming across empty space. Microwaves only offer a key benefit when they have to travel through dense atmosphere with minimal losses. Due to their long wavelength, they diverge too quickly, and are only good for beaming power from orbit to the surface, or if you want to place the rectennas on a planetary surface, covered with atmosphere.
I have serious doubts that any advanced intelligence that creates Dyson swarms will keep using microwaves for power beaming purposes. I don’t understand why they think that microwaves should be interesting at all in this context
Good analogy ljk. The SETI work was no-lose; it could only prove something interesting; disproof of the possibility (which is admittedly very low) of ETI is beyond our capabilities at the moment. Tabby’s Star is almost better as an interesting unknown, if it serves as a running motivator.
Optical SETI will be involved too. It’s a start.
http://stgist.com/2015/10/seti-to-search-for-laser-pulses-near-kepler-alien-mega-structure-star-4649
I wonder whether we still have AM or FM radio by 2500 A.D.
@ljk: Only 10 minutes? Are you sure not 10 seconds?
By 2500 AD where will we have put 9 trillion human beings?
Something drastic is going to change long before we voyage to the stars…
I think…
@ljk. In California you can see sharks and marine mammals with quite short observation periods. Find a rock pool and life, including small fish is evident.
But that isn’t the approach to take. Life leaves signatures that can be detected, providing information on its existence. For terrestrial life, the oxygen signal is notable. We’ve started looking for evidence of KIII and KII civs that impact stellar emissions. So far KIII seems absent assuming our approach is correct, which it may not. But I think the approach makes more sense. SETI restricts itself primarily to active signaling, again wil no success to date. It may be that civs stay tucked unobtrusively around their stars, but just as on Earth, I would expect the predators to leave clear signs.
While lack of evidence isn’t evidence of absence, I think that we should take as the null hypothesis that we are alone in space and at this time, at least in the immediate vicinity, and probably the galaxy and maybe the observable universe. Perhaps an astonishing conclusion that we may be the only advanced technology culture extant. If so, we should take great care and preserve our planet and species for the long term, and make preparations to expand into the Galaxy. I do expect life to be present on our habitable worlds, just not advanced ETIs.
The reason nobody likes comets as the explanation is because it is extremely hard to figure out how dirty icebergs can obstruct up to 22% of an F3 star and not also produce excess infrared radiation.
Why not “Boyajian’s Star”, similar to “Barnard’s Star” or “Teegarden’s Star” where the name of the star uses the last name of the person?
I’m really not convinced by this strategy, it seems more designed to chase headlines than anything that might stand a reasonable chance of success. Similar to the fanfare they make about pointing their radio telescopes at whatever “habitable” exoplanet made the news at the time.
andy said on November 6, 2015 at 15:05:
“I’m really not convinced by this strategy, it seems more designed to chase headlines than anything that might stand a reasonable chance of success. Similar to the fanfare they make about pointing their radio telescopes at whatever “habitable” exoplanet made the news at the time.”
Study the history of SETI since Project Ozma in 1960 and you will see most efforts have been token ones. An example would be to study a few hundred sunlike stars (and this was before we even knew if any of them had planets around them) for a few weeks or so, often when they could get some time on the radio telescope – and it was almost always a radio telescope.
Part of the reason was that radio was firmly established in 1959 by the famous Nature paper on what would become known as SETI. Interestingly one of the inventors of the laser, Charles Townes, advocated Optical SETI in 1961, but that method was drowned out by what can only be called the Radio SETI Mafia until Dr. Stuart Kingsley finally got Optical SETI back into the mainstream of the field in the late 1990s.
There were reasons why SETI has been the way it is for so long: A lack of funding, a realistic fear of being lumped in with the UFO crowd, limited technology, and – dare I say – limited imaginations to a degree.
This is why I am grateful for KIC 8675309, no matter if aliens are not the cause for its unusual appearance: It has expanded the paradigm of what advanced ETI might do and how we may find them for both the general public and even the professional scientific community, who still think radio is the only way to go. This combined with our own progressive technology may finally give us the chance to at last see if we are alone or not in the galaxy.
And oh yeah, that $100 million gift will help, but it will not last forever. And one thing the SETI community has not been the best at is managing its finances properly in terms of keeping their various projects funded consistently. Peeking at the skies once in a while with only a few type of instruments in a galaxy of 400 billion star systems is not going to cut it unless we are very lucky.
Once again I highly recommend this online book be on everyone’s reading list, especially if you want to see humanity find out if other minds exist in the Cosmos or not sometime before Sol becomes a red giant:
http://www.daviddarling.info/encyclopedia/S/SETI_critical_history_cover.html
Could the variations be intrinsic to the star, instead of extrinsic?
Charles Quarra maintains that “microwaves or not it an interesting wavelength for power beaming” and that their only benefit is that they have low losses in our atmosphere. However there are much deeper arguments for the use of microwaves. First of all, microwaves propagate across interstellar distances very well and in some astronomical regions better than any other frequency. But their key utility is that they are a very efficient technology; therefore high-power systems will require less energy to drive them. Efficiency is an economic factor that should not be overlooked. Note that microwaves are used entirely for our communication across the solar system. Lasers, though having lower divergence, also have poorer efficiency and lower power. And they are more expensive. They are in need of development when it comes to sophisticated amplification. All of these technological problems are why lasers are not yet being used for communication across interplanetary communication. Power beaming with lasers is even more demanding, so may come to pass in the future. But for power beaming, microwaves are the only technology that we would use for all but the most demanding missions for engineering and economic reasons.
The reason why you don’t get an RF signal from ETI planets [with an average spacing of 1340 lys per Marconi’s calc] is perhaps they are using smoke signals, passenger pigeons , advanced laser-com , gravity waves or some futuristic Star Track FTL subspace com. What’s the probability of a nearby ETI civilization being comparable in technology to Earth’s?
LJK:
Did you look at the ground, though? On most beaches, you would have seen ample and clear evidence of seaweed an shellfish within a fraction of a second of looking.
Looking for microwave leakage is an example of looking *first* for what we can see. It’s good that optical SETI will also have a look. The odds of us seeing microwave power-beams, that’d be in rather narrow cones to minimise losses, seems remote – but it’s something we *might* get lucky enough to see if the system is full of microwave pushed vehicles and lots of active radar scans all over the sky scoping for incoming matter. However, if the ETIs have graduated to mass-beams for moving energy around the place, then the odds of leakage drop immensely.
On the odds of seeing microwave beaming, there’s this preprint by Loeb & Guillochon: SETI via Leakage from Light Sails in Exoplanetary Systems .
A lot of disappointing KIC~852 headlines this week, at least for lay observers. Even if those headlines are unsurprising.
What was much more surprising to me from Thursday’s press release is how limited the perceptive options actually are for SETI. The Allen Array’s observations seem to require gargantuan energy waste or comically specific exotechnologies by a subject civilization. The SETI Institute’s efforts are the best on the menu, yet by those detection methods an observable extraterrestrial civilization would have to be close by and inefficiently conspicuous — which we could have identified in the Wow! Big Ear days — or distant and impossibly deliberate. As in, to meet our current thresholds for detection a technologically sophisticated and efficient KIC~852 ETI would have had to address our planet specifically, broadcast the galactic equivalent of Bette Midler, and have played that concert over a thousand years before humans were even in the audience.
So maybe there’s no ETI around Boyajian’s Star, as headlines suddenly agree; or there is, and they just had better and quieter things to do in 535 CE. We can’t really tell the difference. And that’s the truly discouraging surprise in this week’s news: humans are exquisitely equipped to ask the SETI questions, but not to answer them.
On the bright side, investigation of Boyajian’s Star has just begun and this is a much-needed exercise in scientific discipline for those of us in the inexpert public. If ETI exists, and humans are to have meaningful future scientific knowledge of ETI, we must knuckle up to the far less sexy challenges that science -has- clearly identified. For example, heading off the carbon holocaust. Multi-yottawatt interstellar telegrams will mean nothing on a silent posthuman planet of hypoxic orange oceans and green sulfide skies. Figuring out what exactly happened around Boyajian’s Star 1,480 years ago is — no surprise — going to require us to prove our intellect again and again and again, here, now.
I love that first sentence of the 3rd paragraph “Thus we can’t rule out the possibility of an extraterrestrial civilization”. The fact that this is still being considered, to me, is astonishing!
” It tells us that we can rule out omnidirectional transmitters broadcasting narrow-band signals at approximately 100 times today’s total terrestrial energy usage, ”
I have to ask myself, would I like to be anywhere near such a powerful radio source? At least not or near Earth. Also if a civilization is in the process of building a form of Dyson sphere, I’m not sure they would commit to using such energy is such a frivolous way.
Such a civilzation as required to build a “Dyson Sphere”, “Swarm”or anything else would have to be 100s of thousands if not millions of years ahead of us, I should think. It absurd to think they would still use radio and what POSSIBLE justification is there for even considering they would try to beam something our direction on purpose? If they exist, I’d say they have a much bigger project on their hands.
It is sheer arrogance to believe we could even conceive of the technology of such a civilization, PLUS what possible social, philosophical, economic even religious influences could be guiding such construction.
The fact intelligence is still -apparently- under consideration IS surprising to me, if true. I say “If true” because I’ll bet the mortgage apparently “Unnatural alien civilizations” is not merely the LAST thing you want to think, it’s the one thing they NEVER really want to find. There would go the last bastion of human uniquness, -our VERY existence- right along with “Earth is the center of the universe” and “Special creation”.
A thought came up, if it actually is a Dyson swarm under construction, we’ll eventually find out as the transits will gradually get deeper and more frequent. Might take some time though.
The idea that a star 1400 light years away from us will be broadcasting traditional SETI-type terrestrial radio directly at us is anthropocentric arrogance at its finest. I understand the SETI scientists are simply eliminating a few possibilities, but if you read some of these deceptive headlines the story is: “SETI found no radio signals, can’t be ET, it’s entirely natural.”
That is a huge, arrogant assumption. Nothing has been proven or disproven, there is no natural explanation that fits convincingly. This star should be under constant surveillance by Kepler and other instruments besides the sad little SETI radio astronomy effort until an explanation is determined one way or the other.
I can’t think of any other deep space research right now even as remotely as interesting or important.
If they are KII we’re seeing them 1480 years ago…
What might they be progressing toward now…
Rendezvous With Rama, hurry up…
This is a very loose and tongue-in-cheek analogy but when I heard the Allen Telescope Array failed to detect any radios signals from Tabby’s Star I couldn’t help but think of an abandoned subdivision that is a few miles from my house. It was going to be a huge 300 house community but when the banking crisis hit in 2008 all work was stopped leaving just a series of paved streets running around empty lots and five completed model homes.
It’s depressing to consider a K2 status alien species able to build a Dyson Swarm suffering from greedy bankers along with irresponsible politicians.
Eniac said on November 6, 2015 at 19:35;
LJK:
I stood on the beach and stared at the ocean for ten minutes. I did not see any fish swimming in that big body of water, therefore no fish must exist in the ocean.
“Did you look at the ground, though? On most beaches, you would have seen ample and clear evidence of seaweed an shellfish within a fraction of a second of looking.”
Ah, but radio SETI doesn’t look at anything beyond its deliberately limited range, namely that self-proclaimed Cosmic Water Hole of 1420 MHz. I get why they look there, but as has been stated elsewhere really advanced beings would probably use more sophisticated (and less leaky) methods of communication through space – and only with members of their own tribe or compatible aliens.
In the case of KIC 8675309, we would have had to assume not only would they be using radio but also aiming their transmissions deliberately and directly at the Sol system almost 1,500 light years away. Thus my ocean-fish analogy. We know there are plenty of other scientifically legitimate and plausible methods of interstellar communication, we just need to get beyond this decades-old paradigm.
By the way, this is not to say we shouldn’t keep looking in the radio realm of the electromagnetic spectrum, as radio is a relatively easy method signalling between stars, but we need to expand our horizons. Optical has advantages over radio such at not needing a special frequency and being very noticeable if a beam is aimed right at us.
Here is a whole range of methods for conducting SETI (and METI):
http://www.coseti.org/lemarch1.htm
Personal Notes: The above piece was the first main article put in SETIQuest magazine, which was only the second serious periodical devoted to SETI and its related fields after the famous Cosmic Search magazine a decade before it. I was the editor and co-producer of SETIQuest, which may be best described as a critical if not financial success in its alltoobrief run.
The figure of the Dyson Sphere in the section “Infrared Radiation” was created especially for Dr. Lemarchand’s article in SETIQuest. I have been both pleased and amused at how many times I have seen this diagram reproduced across the net whenever Dyson Spheres are the topic (without attribution, I have noted, but I think few know its true origins).
I also wrote the section “Concluding Remarks” (the piece needed a proper conclusion), which I am pleased to say is probably the most reproduced part of the article whenever it has been discussed: An issue Analog magazine is one example I distinctly recall.
ljk: Optical SETI has an even LESS chance of producing a positive result at 1400 LY than Radio SETI. Correct me if I am wrong, but; if Darth Vader pointed the Death Star at Earth from a distance of 1400 light years and fired its death-ray beam DIRECTLY AT US, I doubt whether ANY of our most sensitive telescopes would detect any photons at all when the beam passes through our solar system! Tom Mazanek: Even ARTIFICIAL structures should emit SOME IR! Borg Cubes MIGHT be able to adapt well enough to keep all the IR radiation contained within the cubes, but I even doubt that. The ONLY structures in the science fiction literature to pull off this trick would be something akin to Clarke’s “black monoliths”, but with a purpose of not turning a gas giant planet into a star, but instead; of turning a star into WHAT(I can’t possibly immagine). As far as it being some NATURAL intrinsic property of a star, it would be the first EVER detected out of billions and billions of stars! Of course. a K2 civilization Should havethe TECHNOLOGY to do it intrinsically. James Benford: What telescopes ALREADY ON-LINE would have the BEST chance to detect “lightsail leakage” at HIGHER FREQUENCIES than the ATA UPPER LIMIT of 10GHz? In your post on this subject, you mentioned that a recent scientific paper stated that “tens of GHz would be the optimal frequency for the transmitters. Could Green Bank or the JVLA detect these higher frequencies, or we going to have to WAIT for either the SKA or the Chinese “Super Aricebo” to come on-line to do the trick?
Well, Harry, then pick a SETI method you like. I provided a link to a whole bunch of scenarios above.
ljk and James Benford: Wright et al are waiting until a software package is installed sometime next year at Green Bank(which is ALREADY thousands of times as sensitive as ATA)to listen to 1.5 billion channels at once UP TO 115 GHz! This should be enough to detect any king of “lightsail leakage” and just about any kind of other leakage possible. My only concern now is whether Green Bank can DIFFERENTIATE between KIC8462852 and its M dwarf binary companion. Andrew LePage stated earlier that the JVLA COULD. I hope a software package SIMILAR to the one to be installed at Green Bank next year can ALSO be installed on the JVLA sometime in the near future.
AmericaSpace’s take on this event:
http://www.americaspace.com/?p=88392
I just wish the title did not perpetuate the notion that SETI is one monolithic group, which it certainly is not. Nor is radio the only way to search for alien technology.
hi @James Benford,
“But for power beaming, microwaves are the only technology that we would use for all but the most demanding missions for engineering and economic reasons.”
I agree for our technological short-term case. My concern is to assume that advanced ETI capable of creating the transits that we see (assuming that’s the cause of course) will have a preference for MW for beaming. Yes, they could happen to coincide on our same technical preferences and limitations, but my guess is that for the purposes of SETI, microwaves shouldn’t be singled out as special
@Steve White November 7, 2015 at 12:54
“Such a civilzation as required to build a “Dyson Sphere”, “Swarm”or anything else would have to be 100s of thousands if not millions of years ahead of us, I should think.”
I sincerely doubt your proposed timescales, especially when, technically, we human beings have already started down that path with the thousands of square metres of solar arrays we’ve lobbed off the Earth into geocentric and heliocentric orbits. Yes they are spaceprobes and observatories that get power from sunlight for their onboard computations rather than bona-fide powerplants but what of the near future, especially with Japan’s orbital powerproduction plans now that fission is a bad word over there at the mo. I think it logical that our space hardware will expand in numbers totalling hundreds of square kilometres of solar array area. Our fledgling space-based industries will then add to the numbers and then there’s no stopping it, especially as space harvested energy will be used in situ rather than heating up the Earth with that pesky second law of thermodynamics.
For the reasons outlined by James Benford above, microwaves should be in our bag of tools for centuries yet, or they may be our technology of choice for millenia (ignoring New Physics) as it’s proven, versatile and we are exquisitely good at improving those technologies. It may be an excellent way of handling the logistics of building a Swarm and keeping things working within the confines of a solar system.
Dyson Swarms are independent habitats, not the solid shell later folks envisioned and which Freeman Dyson never said was his original design. I do not think those will take hundreds or thousands of years to build unless one accounts for the current pace of the various space programs at enacting even basic colonization of the Sol system.
LJK:
Ah, yes, if your comment was about the effectiveness of SETI, you have a real good point.
As a comment on how likely it is that ETI exist without our knowledge, it does not work. The “looking at the beach” analogy points out that there are many ways in which we could (and likely would) know about ETI, if they existed, with no Searching at all.
Eniac, my comment is largely on our current methods of SETI, which I find to be dated, limited, and quite frankly lacking in both imagination and boldness. Radio SETI still dominates all these decades later in both practice and perception of how the field should operate, when other more advanced and effective methods need to be ramped up. Doing a couple of infrared searches for Dyson Shells/Swarms is again yet another token effort by the SETI community.
A two-week radio search by the ATA of Terry’s Star then having everyone declaring nothing was found was nothing short of ridiculous. When I read those headlines, it made me feel like their efforts were the equivalent if I went outside at night and stared really hard at the part of the sky that star system is in to achieve similar results.
I hope that wealthy Russian’s gift to SETI is put to good use and grows into maturity from the seeds he is planting, because until now the field has largely been running on table scraps and restrained into just a few places on the electromagnetic spectrum. The results are mostly token efforts which the media and general public (and even professionals) interpret as Mission Accomplished.
You want a surprising example of this? In one of the biographies about Carl Sagan, he apparently did a little SETI on the Andromeda galaxy (Messier 31) using the Arecibo Observatory in 1975. By “little SETI” I mean he sat at the control desk and listened to our neighboring galaxy (2.93 million light years away) for any signs of intelligence between the crackling natural radio noise of our Cosmos for a couple of hours. Then he got bored and left.
THIS is the kind of token SETI I am talking about. Yet if you read some other accounts of what Sagan did at Arecibo 40 years ago, you would think he conducted some major scientific research into seeking alien transmissions from our neighboring stellar island. Too many SETI projects have been of this nature.
Even the modern Optical SETI program run by The Planetary Society is largely automated and no one checks on any potential detections until well after a run is completed. Much like they were doing at OSU with Big Ear in 1977.
http://www.planetary.org/explore/projects/seti/optical-seti.html
TPS also used to run a Radio SETI program at the same Harvard observatory until a windstorm knocked down the venerable but old radio dish. Which they failed to inform their members or others for quite a while. Then they let the dish be torn down for scrap. And we wonder why humanity has not found ETI yet.
Given how much more time hypothetical ETI had, and how many more of them there would be, it is far more likely for them to have found us than for us to find them. Regardless of the vigor (or not) of our SETI programs. Even if we keep searching vigorously for millenia to come.
Yes, I know, this is not a reason to not be looking, but it just might be a good reason to spend the money some other way. On discovering exoplanets, for example. I suspect that this is the reason for the sorry state of SETI that you lament.
Well, Eniac, as Monty Python once sang, pray that there is intelligent life somewhere out in space, ’cause there’s bugger all down here on Earth!
https://www.youtube.com/watch?v=dvwH8Qij0JY
Happy Christmas to you Paul, and to all the interstellar travel community!
And to you as well, Jean-Pierre! Thank you for being a reader and a participant in the interstellar community. Have a wonderful holiday.