I hadn’t expected a new paper on KIC 8462852 quite this fast, but hard on the heels of yesterday’s article on the star comes “KIC 8462852 Faded at an Average Rate of 0.165±0.013 Magnitudes Per Century From 1890 To 1989,” from Bradley Schaefer (Louisiana State University). Schaefer takes a hard look at this F3 main sequence star in the original Kepler field not only via the Kepler data but by using a collection of roughly 500,000 sky photographs in the archives of Harvard College Observatory, covering the period from 1890 to 1989.
The Harvard collection is vast, but Schaefer could take advantage of a program called Digital Access to a Sky Century@Harvard (DASCH), which has currently digitized about 15 percent of the archives. Fortunately for us, this 15 percent covers all the plates containing the Cygnus/Lyra starfield, which is what the Kepler instrument focused on. Some 1581 of these plates cover the region of sky where KIC 8462852 is found. What Schaefer discovers is a secular dimming at an average rate of 0.165±0.013 magnitudes per century. For the period in question, ending in the late 1980s, KIC 8462852 has faded by 0.193±0.030 mag. From the paper:
The KIC 8462852 light curve from 1890 to 1989 shows a highly significant secular trend in fading over 100 years, with this being completely unprecedented for any F-type main sequence star. Such stars should be very stable in brightness, with evolution making for changes only on time scales of many millions of years. So the Harvard data alone prove that KIC 8462852 has unique and large-amplitude photometric variations.
That’s useful information, especially given the possible objection to the Kepler findings that they might be traceable to a problem with the Kepler spacecraft itself. Evidently not:
Previously, the only evidence that KIC 8462852 was unusual in any way was a few dips in magnitude as observed by one satellite, so inevitably we have to wonder whether the whole story is just some problem with Kepler. Boyajian et al. (2015) had already made a convincing case that the dips were not caused by any data or analysis artifacts, and their case is strong. Nevertheless, it is comforting to know from two independent sources that KIC 8462852 is displaying unique and inexplicable photometric variations.
As Schaefer notes, KIC 8462852 can now be seen to show two unique episodes involving dimming — the dips described here yesterday for the Kepler spacecraft, and the fading in the Harvard data. The assumption that both come from the same cause is reasonable, as it would be hard to see how the same star could experience two distinct mechanisms that make its starlight dim by amounts like these. The timescales of the dimming obviously vary, and the assumption would be that if the day-long dips are caused by circumstellar dust, then the much longer fading that Schaefer has detected would be caused by the same mechanism.
Image: KIC 8462852 as photographed from Aguadilla, Puerto Rico by Efraín Morales, of the Astronomical Society of the Caribbean (SAC).
Thus we come to the comet hypothesis as a way of explaining the KIC 8462852 light curves. Incorporating the fading Schaefer has discovered, a cometary solution would require some mind-boggling numbers, as derived in the paper. From the summary:
With 36 giant-comets required to make the one 20% Kepler dip, and all of these along one orbit, we would need 648,000 giant-comets to create the century-long fading. For these 200 km diameter giant-comets having a density of 1 gm cm?3, each will have a mass of 4 × 1021 gm, and the total will have a mass of 0.4 M?. This can be compared to the largest known comet in our own Solar System (Comet Hale-Bopp) with a diameter of 60 km. This can also be compared to the entire mass of the Kuiper Belt at around 0.1 M? (Gladman et al. 2001). I do not see how it is possible for something like 648,000 giant-comets to exist around one star, nor to have their orbits orchestrated so as to all pass in front of the star within the last century. So I take this century-long dimming as a strong argument against the comet-family hypothesis to explain the Kepler dips.
If Schaefer’s work holds up, the cometary hypothesis to explain KIC 8462852 is deeply compromised. We seem to be looking at the author calls “an ongoing process with continuous effects” around the star. Moreover, it is a process that requires 104 to 107 times as much dust as would be required for the deepest of the Kepler light dips. And you can see in the quotation above Schaefer’s estimate for the number of giant comets this would require, all of them having to pass in front of the star in the last century.
The paper is Schaefer, “KIC 8462852 Faded at an Average Rate of 0.165+-0.013 Magnitudes Per Century From 1890 To 1989,” submitted to Astrophysical Journal Letters (abstract).
Two ideas come to mind immediately:
1. A big planetary collision/breakup in the recent past (maybe 500y ago?) with slowly dimming afterglow. Although this still has the issue with the lack of infrared.
2. Ongoing ALIEN construction project.
tee hee
If this long-term dimming is due to an ongoing Dyson sphere engineering effort, how long will it take to block all visible light? I guess several hundred to thousands of years. Is this a plausible time span?
We should then see a shift to infrared.
Also, distance based on absolute luminosity would be over-estimated.
This star is highly evolved. Surely some sort of stellar variability could account for these changes ? There are plenty of variables that change their luminosity by magnitudes. Kepler was the first of its kind for stellar science as well as exoplanet so as has already been pointed out it shouldn’t be a surprise if it discovers some new form of stellar phenomena or indeed even several.
On the other hand, the theory that the Kepler fades are the result of the on-going construction of a Dyson sphere / swarm seems to me to be entirely consistent with these new data.
I wonder if this star appears in the IRAS data and, if so, if there has been an increase in its IR flux since then.
((( joke ahead )))
This is clearly definitive proof that an alien civilisation has been building a Dyson sphere at KIC 8462852 over those 100 years!
(runs for cover :-)
So the Dyson swarm is farther along that we thought?
I believe there is one vaguely similar anomaly in earlier Kepler data for star KIC 4110611 ,which ultimately turned out to be one of a close bound system of five stars. Took yeas of investigation to establish though as I suspect this will. Complex , but effectively as previously stated ,one of the commonest causes of false positives with transit photometry , eclipsing binaries. I can’t say it enough ,boring as it may be, “common things are commonest” ( though there are of course lots of rare things !)
If you were a Kardashev civilisation capable of building Dyson spheres my hunch is that you could do it quicker than a hundred years and would use energy rather than matter . Much easier .
@Ashley Baldwin January 14, 2016 at 12:29
‘This star is highly evolved. Surely some sort of stellar variability could account for these changes ? There are plenty of variables that change their luminosity by magnitudes.’
Starspots can hang around the polar regions for years and can gather in large groups, if the star is also a fast spinner as this one is the ‘gravity darkening effect’ flux changes would be more pronounced but 20% decreases is a hell of a lot of dimming.
I’m not an astronomer, but this paper is something of a bombshell, right? It seems to demolish all normal hypotheses about the KIC 8462852 light curve. It will be interesting to see if it holds up to peer review, and if the calculations can be replicated.
What are the chances that KIC 8462852 is actually much younger than has been assumed? Could this account for all the light variations we’ve seen, over the various time scales? I believe this is the hypothesis that Jason Wright favors.
The cometary hypothesis was a hale mary from the beginning. You know what .. This is getting to be creepillyy .. interesting don’t thou think?
All these scientific papers and research based on massive searches for AI based intelligent civilizations .. and then when you find a good candidate everyone is getting cold feet and fudging..
@Ashley Baldwin
“If you were a Kardashev civilisation capable of building Dyson spheres my hunch is that you could do it quicker than a hundred years and would use energy rather than matter .”
I bet it was a no-bid contract.
@ Ashley Baldwin Building a Kardeshev Dyson sphere quicker then a hundred years ..
Just how many billion square kilometers of surface area we talking about here. I would think it would take ten thousand years..
One thing that I see no discussion on is .. this is an F3 home star how old could it be .. not more then a billion or two I presume. They (the aliensis) would then be on a pretty fast track?
Or perhaps they are from the little dwarf nearby .. wanting something a little more warmer in the cold of the night.
It would be interesting to measure the V magnitudes from the plates (or R) and see if there’s also a trend in B-V or B-R. The plate drift in these colors could be corrected.
If either ratio stays constant over the date range, then the star would be dimming in all colors… which would be extremely unusual.
If the ratio indicates that the star is getting bluer or redder over time, it would indicate a new stellar phenomena. Maybe the very, very long period indicates a new type of pulsating variable star.
Thanks Michael. A classic example of what big samples pull out perhaps, the full inverted bell curve complete with long thin tails. Still (just ?) within the realms of recognised phenomena though an extreme example. Whether intrinsic stellar variability or not , pushing the limits of normal as with KIC4110611 and its quirky stellar ménage-a-cinq.
To be fair I don’t think the star is that heavily evolved , possibly just beginning to though I guess ( not being a stellar astronomer ) this is a time of significant magnetic field instability related to changes in convection and the rapid rotation you allude to giving rise to substantial differential rotation that could lead to widespread sun spots. I’ve certainly seen impressively extensive examples of sunspots in interferomic images of Betelgeuse and also on Doppler tomography of other stars .
It sounds like a bombshell to me. People with reputations in the field will, and should, seek natural explanations and they may find one but to me the idea of some kind of megastructure being built over a longer term seems to be the simplest explanation; assuming the long-term data is verified.
“Curiouser and curiouser” to quote Alice.
Would it be possible to create a software that would combine the scanned(preferably completely) archives of Harvard Connection with search for dimming patterns similar to those in this star?
”
Bilal Gicvan January 14, 2016 at 15:52
” All these scientific papers and research based on massive searches for AI based intelligent civilizations .. and then when you find a good candidate everyone is getting cold feet and fudging..”
It’s not the first candidate, they were several ones before. This one is though very well covered by media and a bit different from the previous ones as it can’t be explained by other phenomena. However we know multiple candidates for Dyson Spheres from previous searches.
I was wondering if there was a type II civilization in around Tabby’s star wouldn’t they need to get rid of of comets and asteroids that could prove hazardous to a Dyson sphere? Maybe they are rounding them up as we speak?
Two ideas on further tests:
1.) Someone should look at a large sample of the Harvard Plate data to see how often these century-long fades are.
2.) There is a new Hubble AO out today (Hubble Space Telescope Cycle 24 was just announced). I wonder how the review process would view a proposal for HST to sit on this object for a few orbits to see if there are smaller fades from smaller occulting objects.
David Bernard January 14, 2016 at 17:24
“I was wondering if there was a type II civilization in around Tabby’s star wouldn’t they need to get rid of of comets and asteroids that could prove hazardous to a Dyson sphere? Maybe they are rounding them up as we speak?”
Get rid of them? That’s raw material!
Think I’ll take this excuse to salute DASCH and similar programs. Incredibly important work.
@Ashley Baldwin
Our notion of time is very limited to the fragility of the precarious vessels of our souls. Our lifetimes last for a blink of time in the great scheme of things.
100 human years could be nothing for a more advanced species who have mastered total control of their own biology.
The other day, even here on Earth, I read about some of the oldest known animals living among us today
https://en.wikipedia.org/wiki/Jonathan_(tortoise)
Apart from a different perspective of time, different species can have different motivations for building out stellar scale infrastructure.
It would be too much of a coincidence if we were so lucky as to be witnessing the first and only such structure built by any given species.
It would be “commoner” to stumble upon merely one of possibly hundreds or thousands such construction sites.
An advanced species would build one Dyson sphere, but a really advanced species would automate the process to capture a number of stars in a stellar group.
However long it takes to deploy and automate the roll out of swarms of builders may not have (and on Earth frequently doesn’t have much) to do with the urgency or ability of the property owner.
Would someone please take a stab at describing the the fate of all that energy being absorbed? I know a little teensy bit of thermo…high “quality” energy degrades to longer and longer wavelengths…ultimately heat.
If there is a society harvesting that star’s output at the 20% level how could they prevent it from reappearing at some longer wavelength? What could anyone do with that much power?
Ship time one way at constant 1 gee accelerate/brake is 14.21 years for the 1480 LY trip. Jus’ sayin’ :)
IR observations of KIC 8462852:
http://arxiv.org/ftp/arxiv/papers/1512/1512.00121.pdf … (4.2 microns) http://arxiv.org/abs/1511.07908 (4.5 microns)
http://arxiv.org/abs/1512.03693 (850 microns and 273 GHz)
Thompson et al (1512.03693) do a nice job summarizing the available data (see their figure 3). The 4 micron data constrain the IR flux to be < about 100 K, but a swarm (of dust or other small objects, natural or artificial) with a temperature of 30 K could emit roughly the same IR flux as the star itself emits in the visual _and be consistent with the current observational constraints_. (This “case iii” has a mass of 7.7 M_Earth in their dust model, but that mass estimate is not relevant in the hypothesis of an artificial swarm.)
So,
1.) The data are indeed consistent with a Dyson swarm and
2.) If this is a Dyson swarm, it is a very thermodynamically efficient one and
3.) Someone really needs to look at this object at 900 GHz with ALMA.
I think Paul noted that the Allen array had a listen. But the ATA is an interferometer of 40 x 1 meter dishes. Of those about 30 are working. That is a collecting area of about 20 square meters. Is that enough to be useful?
Hopefully someone will inform us that my information is incorrect and the ATA has become SETI-ready?
Over the years many many millions of dollars have gone into this “promise” and so precious little has come out of it. Heads really should roll in the insular california seti camp…who seem to market themselves as your one-stop shop for all your seti needs. Time for some fresh meat.
At some stage Tabby’s star may warrant professional investigation. That time may be now. It would be a shame if negative results from ATA discouraged further listening programs
@Coacervate January 14, 2016 at 21:35
‘Would someone please take a stab at describing the the fate of all that energy being absorbed? I know a little teensy bit of thermo…high “quality” energy degrades to longer and longer wavelengths…ultimately heat. ‘
Its is most likely been reflected rather than absorbed, sulphur dioxide could reflect a lot of the light rather than absorb it. I suspect a moon like Io around a planet in a very eccentric orbit or indeed the planet itself is evaporating emitting huge amounts of reflective material to cause the dimming events. Gravity darkening is also having an effect to skew the light curve.
Great update Paul. It will be interesting to see how this holds up in peer review. If you read this paper, the manner in which the measurements are compiled from the plates seem open to some degree of interpretation or error.
Consider that the author admits there is already some degree of variation in the magnitudes recorded on the plates (0.13 mag), plus an accuracy ‘error bar’ based on who is doing the measuring of the point source: ~0.3 mag for an ‘inexperienced’ user and ~0.1 mag for experienced users. The author is obviously an experienced user. But considering the reported slow decline is just 0.16 mag over 100 years, I’m wondering if this trend is actually as significant as presented…
Just when I thought this discovery was fading away! Such a surprise to see this new data! This diming event has made me wonder if it could be the result of an ETI shade beacon. Does anyone here know if this diming effect is oreintated across the galactic plane?
@Ashley Baldwin
I had to dig around for it and then remembered it is in a past CD post.
http://www3.mpifr-bonn.mpg.de/staff/mmassi/c6-StellarActivity.pdf
Potentially a planet has a close approach and the magnetic fields of the star and planet are creating star spots on the stars surface which persist creating the dimming effect. It happens in another system HD 189733, perhaps a planet is pulling the star spots to the polar region where they collect making the effect much larger.
http://www.wired.com/2014/11/science-graphic-week-magnetic-stars-planets/
Dyson sphere or not it just shows how desperately we need to discover some form of alternative , independent life. I cant even imagine an alternative single cell organism though it might do some of the things we were familiar with , but as to alien intelligence and psychology . Not a clue . All options apply !
Anyone read the Alastair Reynolds – Revelation Space -series? Super-old AI designed to destroy any intelligent life as soon as it reaches a certain technological level. They dismantle the whole system to build a weapon to destroy the star. Maybe the system is being destroyed? Bits and pieces of small and large planets flying around?
I dont get the Dyson sphere -thing? With that extreme hightech available, why not just extract all the energy you need from pure vacum or just build a fusion reactor on a chip with a 1000 year waranty and hand out to all your citizens at birth/ or build*
You could probably power a whole star-cruiser with that “fusion on a chip”
*”build” -as in a whole society transcendence to digital instead of biological.
Data points: How many plates old are we talking? Hopefully several. Even so, is it reasonable to compare 2015-ish data (which is CCD collected and IC stored) with 120 year old data (collected and stored on a chemically etched plate)? To obtain gnat’s ass magnitude changes? As Frank H suggested: Is the star dimming at all colors? There is still an absence of IR to explain from any viable hypothesis. Marshall’s idea for the HST to concentrate on Tabby’s star is a great idea, dig in and look for smaller duration events.
@EricSECTW
What would be the time resolution, the duration of time gaps between new data points for any measurements to be considered?
Say, if a year’s worth of dimming in the last century can be confirmed to be similar to this year’s dimming, would that be enough validation?
In that case, it would take a year to collect enough data.
Or can it be reasonably calculated in less time?
What if the aliens suspended construction this year, but had been busy building for the previous 100 years?
:-)
1.) The WOW! podcast has a special episode devoted to this paper. It is well worth a listen if you are interested:
Season 3 Episode 3 – The Slow and Fast Dimming of Tabby’s Star, in which
Host Paul Carr talks to Dr. Bradley Schaefer about his research showing a dramatic dimming of Tabby’s Star over a century.
http://www.wowsignalpodcast.com/2016/01/season-3-episode-3-slow-and-fast.html
2.) The Harvard plates have been fundamental to long term (optical) astronomical research for a long time. For example, when the 3C273 (the first Quasar recognized) was discovered to be an unusual “star,” Harvard plates showed it had been varying for almost a century, at times rapidly, which showed that it was a very small object for its apparent brightness. Properly cared for, glass optical plates will basically last forever. See Figure 1 in
http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1985AJ…..90.2474A&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf
3.) The USNO has a lot of old plates, I will ask and see if there is any chance of a independent dataset from those.
Awesome article by variable star guru Bradley Schaefer. Be sure to download and read the entire paper. Bradley explains how the data was collected. He discusses the potential error bars for observations. The Harvard glass plates are very stable and are a very reliable data source. Maybe more reliable than modern sources. One Hundred twenty years from now try finding something to read a CCD data disk that was recorded in 2016.
My other thought was maybe a couple of trillion Von Neuman machines are dismantling the KIC842852 system. Read John Ringo’s excellent military sci-fi book
Von Neuman’s War
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“Get rid of them? That’s raw material!”
True enough, they probably would use it as building material, I was simply stating it from another point, flying objects in the solar system wouldn’t be helpful to a Dyson sphere civilization, I take this example from Ringworld.
I wonder if they are aware of the possible Proxima Centauri micro lensing event this February – http://hubblesite.org/pubinfo/pdf/2013/22/pdf.pdf
That offers a possibility of discovering a distant planet, and could use intensive observations.
beermotor: That is EXACTLY what Gerald Harp of The SETI Institute said! I can’t WAIT to hear his take on the new data! Ashly Baldwin: Donald Trump could do it EVEN FASTER! Bilal Gicvan: Read “Pandora’s Star ASAP! Marshall Eubanks: I thought that ALMA was TOO FAR SOUTH to observe KIC8462852. Correct me if I am wrong. Frank Smith: Don’t forget “2010: Odessey Two”> Maybe “Black Monoliths” after all! I have JUST ONE QUESTION: How does BBradley Schaeffer’s DASCH data mining DIFFER from Boyajian et al’s? In the Boyajian paper, 700 plates were observed @ a 10% dip detectability threshold and NOTHING OUT OF THE ORDINARY was found. Are the plates Schaeffer used MORE SENSITIVE? Did He use a DIFFERENT analysis code? What gives?
Bilal Gicvan: Exactly damn right. Thanks for saying it for me. Deep down many people do NOT want to find another civilization. They want, and need to feel unique. And so, if the comet idea melts down, they will still torture something else and try to make it fit.
Something obviously REALLY strange is going on around Tabby’s Star, and I KNOW it’s not scientific, but my gut tells me a manifestation of INTELLIGENCE…
I understand that some of the angular momentum of the solar system resides in the planets etc and that therefore the sun rotates more slowly than if it contained the whole mass of the solar system. I note from these articles that KIC 8462852 is rotating faster than might be expected for a star of it’s type and assumed age. What would happen to the speed of rotation of the sun if for example one were to “disassemble” Jupiter and move its material closer to the sun? In the case of KIC 8462852 what mass might need to be moved from where to where to cause its spin to be faster than expected?
Curiouser and curiouser as Alice said.
Clearly something very strange is going on with that star.
Dyson or megaengineering activity is already very low on the list of possible causes. Two couple reasons occur to me to make those possibilities even more unlikely.
The original paper considered a range of possible shapes for potential occulters and estimated they should have to be at approximately Jupiter’s distance from KIC842852 which would seem to be quite suboptimal for mega-structures which I assume would be primarily designed to capture the star’s energy. I don’t know how much stock we should put in those preliminary numbers since the recent paper has cast serious doubt on the cometary hypothesis.
The second reason is, the Kepler light curves seem way too random, I envision mega-engineering would likely proceed in stages, stepping up from smaller building units to larger units. I would expect to see a more smooth distribution of dip depths corresponding to the unit sizes.
I’m now suspecting that whatever’s going on, it’s occurring on the star’s surface, some kind of exotic starspot activity that’s blocking significant percentage of the light.
As for the idea of blocking dust, is it plausible that some kind of materials may not radiate at the IR frequencies we’d expect, but may be radiating at different ones, closer to microwaves? So is it possible that the dust hypothesis may not be totally dead?
These Dyson Swarms/Spheres/Shells from Orion’s Arm will if nothing else help us all think outside the box when it comes to the concept – as if this isn’t already well outside the box for humanity now:
http://www.orionsarm.com/eg-article/4845fbe091a18
Marshall Eubanks writes (re Pale Red Dot):
They are, and as a matter of fact, I have just finished up an essay for Pale Red Dot that will be published on their site in a week or two. It mentions the microlensing prospects and other Proxima planet hunting techniques and their results so far.
I am trying to get people from the AAVSO and Dr. Boyajian to comment on this for the podcast, but it may have to wait. To me, the key thing is what can be done observationally to constrain hypotheses further, or suggest the nature of the occulter (safe assumption it’s an occulter of some kind, since the star appears ordinary?). As Brad Schaefer mentions in the interview, we need to catch it in the act. I am also going to contact Duncan Forgan and ask him what he thinks, and if he wants to comment publicly, since he studies this sort of thing. Duncan also does theoretical SETI studies, and I had him on the podcast in 2013.
How often have I said to you that when you have eliminated the impossible, whatever remains, however improbable, must be the truth?
-Sherlock Holmes
Fascinating!
-Spock