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KIC 8462852: A Dusty Solution?

Research into Boyajian’s Star, otherwise known as KIC 8462852 or ‘Tabby’s Star,’ has continued in robust fashion even as many of us were distracted by that other curiosity with a faint SETI potential, the interstellar asteroid `Oumuamua. In both cases, a highly interesting object provoked speculation as to its origins, with Boyajian’s Star getting the lion’s share of attention because the unusual dips in its lightcurve proved hard to explain.

Now a team of more than 200 researchers led by Tabetha Boyajian herself is drawing useful conclusions about the star. Also on the team is Penn State’s Jason Wright, whose interest in possible SETI signatures led him to point out that engineering on a vast scale could not immediately be ruled out. The paper now being made available in The Astrophysical Journal Letters shows that the star dims more at some wavelengths than at others.

And that is, to say the least, problematic for the idea that an artificial megastructure orbits Boyajian’s Star. The paper, titled “The First Post-Kepler Brightness Dips of KIC 8462852,” draws on data collected by Boyajian (Louisiana State) and colleagues as a result of a Kickstarter campaign in which some 1700 contributors donated money to observations through the Las Cumbres Observatory, a network of robotic telescopes with northern hemisphere sites in the Canary Islands and Hawaii. Follow-up data were acquired from a number of other instruments.

The observations ran from March 2016 to December 2017, with four main 1–2.5% dips, beginning in May of 2017 and named “Elsie,” “Celeste,” “Skara Brae,” and “Angkor,” persisting on timescales from several days to weeks. What analysis of these dips shows is not consistent with any solid structure around the F3-class Star. As Wright explains on his PSU site:

Eva Bodman has done a lot of work to characterize how much deeper the dips are at blue wavelengths than red ones. If there were opaque objects blocking our view of the light, the star should get equally dim at all wavelengths. Instead, Eva finds that the blue (B) dips are much deeper—about twice as deep—as they are when we look at infrared wavelengths (i’ band, just beyond human vision).

This is consistent with ordinary astrophysical dust, and a major conclusion of our paper: the dips are not caused by opaque macroscopic objects (like megastructures or planets or stars) but by clouds of very small particles of dust (less than 1 micron in typical size). We can also say that these clouds are mostly transparent (“optically thin” in astrophysics parlance).

Image: Analysis of LCO data by Eva Bodman.

This work marks the first real-time detection of a dip in brightness for this unusual star, and as the paper notes, “Triggered spectroscopic and polarmetric observations taken during the dips reveal no large, obvious changes compared to out of dip observations.”

The paper goes on to say:

Invoking dust still challenges our creativity in developing a unified theory to explain all the observations; however, the models of Wyatt et al. (2017) give hope to a swarm of yet unspecified objects in an eccentric orbit (in this case, exocomets, with an alternative being dust-enshrouded planetesimals as proposed by Neslušan & Budaj 2017) causing the brightness fluctuations. Continued monitoring to detect events in the future will help narrow down any periodicity within the dip occurrence, which would strengthen the argument that the source of the obscuring material was in orbit around the star, as opposed to density fluctuations in the ISM, etc.

It would have been exciting, to say the least, to find evidence for an artificial cause of Boyajian’s Star’s peculiarities, but I find this work exhilarating in its own right. What we have here is a highly publicized, privately funded investigation into an enigmatic phenomenon that now seems to be closer to a solution. That extraterrestrial engineering is not involved doesn’t diminish the power of the process, in which scientists examined an observational anomaly from all angles and counted an ETI hypothesis among the possibilities.

Bear in mind that using through the Kepler data on Boyajian’s Star alone would not have been sufficient because ground-based follow-up observations were not contemporaneous. That made the ability to summon up a crowd-funded campaign to observe with various instruments at differing sensitivities, resolutions and wavelengths an essential component in this result.

A friend asked not long after the Boyajian’s Star story broke whether I would be disappointed if it turned out to have a ‘boring natural cause.’ But that’s just it. I don’t find natural causes boring, especially when they push us to the limit to explain them. We still have a mystery here, because the original comet hypothesis — or the idea that some kind of circumstellar material is responsible — gains new life at the same time that regular dimming of the star itself — through mechanisms not yet understood — cannot be ruled out. Getting a handle on unusual astrophysical phenomena has a deep allure as we continue to learn about the cosmos.

Where next, then, with Boyajian’s Star? The paper concludes:

We emphasize the importance that continued monitoring will bring to our understanding of the physical processes responsible for the light curve features. In general, precise, long-term photometric monitoring to detect future dips is a level-zero requirement. These data also provide the means of informing planned triggered observations such as high-resolution spectroscopy to study the events in more detail. Furthermore, extended photometric monitoring will enable us to characterize the star’s long-term variability (Schaefer 2016; Montet & Simon 2016; Meng et al. 2017; Simon et al. 2017), which is thought to be linked to the dips in some way. All-in-all, the apparent low duty cycle of the dips, unclear predictions on when they will recur, and fairly unconstrained multiyear timescales of the long-term variability will require a committed, intensive monitoring program spanning the next decade and beyond.

The paper is Boyajian et al., “The First Post-Kepler Brightness Dips of KIC 8462852,” Astrophysical Journal Letters 2018 January 3 (preprint).


{ 69 comments… add one }
  • Chris S January 3, 2018, 11:54

    What if it’s a black cloud, a-la Fred Hoyle? A distributed intelligence in orbit around KIC 8462852 using solar power to maintain a robust virtual realm for whatever? Maybe analogues to Baxter’s photino birds from the Xeelee sequence, inexorably killing the star? A von Neumann machine of colossal proportions deconstructing the star or objects in its neighborhood.

    • Ron S. January 3, 2018, 16:25

      When you find yourself reaching for increasingly improbable hypotheses to explain the data in order to support your preferred outcome you are almost certainly on the wrong track.

      • DJ Kaplan January 3, 2018, 16:42

        A scientific approach starts with NOT having a preferred outcome, whether with aliens or without aliens. As long as we have biases, we will never figure this out.

      • Ashley Baldwin January 3, 2018, 20:46

        I couldn’t agree more. As Sherlock Holmes famously said ” We need more data . Without data, facts are made to fit theories rather than theories to fit facts “.

        I’m sure this will run for years . This paper alone has over two hundred authors . Wow ! That’s a lot of theories . I think this is best summed up by a quote from the “Discussion” section ….”invoking dust still challenges our creativity in developing a grand unified theory to explain all the observations ” . Somewhat speculative and also focuses exclusively on an external occultation theory rather than an intrinsic stellar explanation. It’s as if because Kepler was original a transit photometry mission looking for planetary transits that the only explanation allowed for this anomalous finding can be transit or occultation related .

        We started with Dyson Spheres and gradually moved down to cometary swarms , large ringed gas giants to circumstellar or interstellar dust of increasingly different sizes . Paul knows my feelings on this and I agree that although the explanation will undoubtedly be “natural” ( something constantly redefined ) it certainly won’t be boring . ( a Dyson Sphere would have been great though !)

        To return to the paper again in the “Introduction ” section it is stated that.. ” KIC8462852 is a peculiar variable star ..which manifests itself in asymmetric drops in brightness of up to 22% , many of which last several days” before going on to say ..” despite being nothing other than an ordinary main sequence F3 star ..” Surely by its very nature , intrinsic or extrinsic KIC8462852 is anything but an ordinary star? Nothing else exactly like it has ever been observed before or after !

        That said , I would posit that F type dwarfs are unusual stars by their very nature and position in the main sequence – the more so as they become earlier . Transforming from Sun like , intermediate mass slow rotators and magnetically benign F9s, to A type rapid rotating ,potentially magnetically active and unpredictable F1-3s. Jim Kaler ( Emeritus Professir at the Univetsity of Chicago and leading stellar astronomer aptly describes F type stars as “stars in transition .” in his book “Stars and their spectra ” for just this reason .

        KIC8462852 rotates in in less than a day , very much at the rapid end of the class. It may even be somewhat squashed or oblate . With a mass of 1.43Msun it is close to the 1.5 Msun limit where it has little or no convective envelope to slow it down and has a predominantly convective rather the radiative core . Such stars can be ( but not commonly ) very active magnetically – probably through a combination of the factors described above and also if their magnetic and spin axes are offset. So called “oblique rotators “. Magnetically active stars have active photospheres with extensive sunspot activity , much more so than the sun. ( with hundreds of Gauss strength fields versus the Sun’s paltry 1-2) . The commonest false positives for Transit photometry ? Spectroscopic binaries , which the robust spectroscopy and photometry carried out for this paper seem to exclude , and….sunspots .

        Ockham’s razor is sharpened .

        Are there any facts that support this a cause Watson ? Well yes . Sheikh et al applied an avalanche statistical review of the KIC8462852 photometry that strongly suggested a phase inversion between two separate states strongly suggestive of a magnetic basis A more recent review of the same spectroscopy used here, by Foukal ( referenced here but hastily dismissed ) also supported a magnetic cause mediated through localised photospheric cooling and sunspots

        Another potential driver to magnetic activity in a star of KIC8462852 would be its age. If only young ( less than a few hundred million years ) it might just be big enough to still possess its internal ” fossil ” magnetic field of creation that could then interact chaotically with any internal convection/ rotational Dynamo field . If older then it could be beginning to evolve off the main sequence with all the unpredictability that brings not least with flux transfer from core to surface as well as magnetic variations .

        So early F dwarfs are anything but ordinary as a class and have the further potential to be extraordinary on rare occasion . Presumably not commonly , but given Kepler observed 150K stars of which about 10 % were F dwarfs , should we be surprised to find a few distinctly atypical examples amongst an atypical group ? It should be remembered that the F class includes the most famous variable stars of all , the Cepheids . To say nothing of a smattering of other atypical magnetically variable Ap and Am stars spread throughout the class and into the A spectrum. Nothing like KIC8462853 but illustrative of what F type stars are capable of and why .

        There is mention in this article of Bradley Schaefer’s diligent analysis of old photographic plates to show a century long decline in KIC8462852’s brightness ( he is one of the co-authors ) . This has been challenged but ironically an uncommon not previously described intrinsic stellar variability would also potentially fit with its findings.

        What surprises me most is that everyone is so surprised by KIC8462852 . A we have more large field extended precision time series spectrophotometric studies I’m sure we will encounter other such oddities . I hope PLATO lasts for more than its four year primary mission and continues to stare at the same field for a decade as that will be close to a lot of stellar natural activity cycles as we see with the sun.

        So that’s my alternate take and I thank Paul for a thought provoking essay ( and the get in ) . I will finish by citing one last quote from the paper’s “conclusion” ….” the observed dips appear to be in some tension with intrinsic cooling of the star “.

        I apply tension to my facial skin to get a closer shave. I think a bit of tension can do no harm in allowing Ockham’s razor to get some of the hair off Tabby’s star and help us to see the mysteries that lies beneath….

    • Alex Tolley January 3, 2018, 16:42

      Or just dust that presumably is not evenly distributed but in clumps.

      I thought dust had been ruled out early in the analysis, but this result seems to suggest the cause is dust.

      • HSchirmer January 3, 2018, 19:49

        Early analysis ruled out “shattered planets” and “late heavy bombardment” levels of dust, because we’d detect the IR from planetary mass dust clouds. Refined calculations found that the dips could be produced with only ~10-20 comets worth of dust, which wouldn’t really be detectable.

      • Ashley Baldwin January 4, 2018, 8:32

        They initially ruled dust out early on , with the clear observational absence of any evidence of an infrared excess typical of circumstellar dust ring. This appears to have now evolved into an extended theory that rather than a “solid dust mass” ( whatever that is ) it was some varisnt that is 1/ More diffuse 2/ Possibly in the interstellar medium between Sol and KIC8462852 and 3/ the dust particles would have to be of a distinct particle size – this last to presumably try and explain the absence of infrared emission .

        Facts made to fit theories rather than theories to fit facts .

        Ashes to ashes and dust to dust

  • ljk January 3, 2018, 15:24
  • tchernik January 3, 2018, 16:06

    Potential LGMs (that is, the little green men of pulp sci/fi folklore) have an illustrious history as triggers for astronomical discoveries.

    Usually, motivating the proposal of ways to discount them and explain them as natural phenomena.

    Seems Tabby’s star falls in the same category of discoveries. Bummer, but the good part is that knowledge was gained and that’s always good.

    • Andrei January 4, 2018, 16:31

      Yes such ideas heard many times, natural Masers suspected of being artificial. Quasars suggested as Kardashev civilization powerplant, and Pulsars thought to be cosmic lighthouse for starship navigation.
      With so many examples I was more than little suspicious on the idea of Little Green beings building Dyson sphere in our little corner of Kosmos.

  • Geoffrey Hillend January 3, 2018, 16:27

    I’ll wait for the high resolution spectroscopy; I’ll agree that it is most likely dust if there is a big infrared signature.

    • Ashley Baldwin January 4, 2018, 8:47

      Fancy a bet that they find an infrared signature ?

      The low RES spectroscopic data here is dismissed in excluding dust as a cause BUT dismissively in excluding an intrinsic stellar explanation to the dimming .

      Foukal’s study used EXACTLY the same spectroscopic data ( to be fair made available by Boyajan ) to find that phosphospheric activity and sunspots DID explain the dimming , likely due to a rare but real magnetic origin. Entirely consistent with the findings of Sheikh et al , Hippke and others.

      As Paul says this is indeed an unusual star . It is often said in medicine that “Common things are commonest but there are lots of a rare things”

  • Robin Datta January 3, 2018, 17:05

    Next, a transmission from Boyajian’s Star: “Pardon our dust”?

  • John walker January 3, 2018, 18:50

    Dr. Boyajian was very reliable in her updates to the funders. I enjoyed the process greatly. Shame that despite 18 months of observations a repeat of the 20% dips was not seen. The irregularity in the light curve remains interesting.

  • Neil S January 3, 2018, 20:39

    If I were an alien race building a megastructure around a star and wanted to disguise that fact from any bloodthirsty aliens, the last thing I’d do is build it out of something opaque. I’d use a material with light transmitting properties like some common astronomical material, say, dust.

    • ljk January 4, 2018, 12:40

      Most professional astronomers don’t want the answer to be aliens. It will disrupt the neat and clean explanations for everything in the Universe, to say nothing of finally making humanity realize we are the not the special focus of the Cosmos and its presumed Creator.

      For political/military/industry leaders and the general public, this is an even stronger sentiment, except for those who expect ETI to come and “save” us from ourselves.

      • Ron S. January 4, 2018, 14:14

        “Most professional astronomers…”

        Your attempt to smear an entire group of professional scientists only exposes your own biases. You are in dire need of a mirror.

        Of course everyone has biases and astronomers are no different. The mark of a good scientist is to look at the data and evaluate competing theories without being swayed by their personal biases.

        • ljk January 4, 2018, 15:17

          Happy to be proven wrong here, but every time I see an article on Tabby’s Star with the latest round of astronomers saying it is giant comet swarms, huge rings, or immense dust clouds and not ETI building a Dyson Shell, the headlines practically read “Wheh! No Aliens!” and those interviewed also seem relieved when they are not talking about ETI with no small amount of social and no doubt professional embarrassment.

          Of course it is understandable in one sense regarding beings who can think up and then actually build a structure the size of a solar system. The power and abilities of such a civilization would naturally bring a level of fear to beings who have barely gotten out of their cosmic cradles and until only recently entertained such notions just past the line of science fiction and sheer fantasy. Tack on our decades of stories about alien invaders and our own bloody history of what a powerful society often does to those who are smaller and weaker and you have a perfect storm in terms of attitude towards the rest of the Universe.

          This isn’t just about Tabby’s Star in particular, as you may have guessed. TS is just the most prominent symptom of our cultural angst, fear, and ignorance when it comes to cosmic forces. I suppose I should be grateful for the intellectual baby step that TS has even been seriously considered as the construction of an alien Dyson Shell or something similar. Even if it is proven to be ultimately wrong and Dyson Shells turn out to be a misstep when it comes to the concept of alien megastructures and how a sophisticated intelligence might actually go about expanding into the Cosmos, the fact that serious thinking outside the box in the early 21st Century is taking place at all is heartening for a positive and progressive future.

          • Harold Shaw January 5, 2018, 14:14

            I understand your frustration. In the context of Sagan’s test, if the only life and industrial intelligence is from Earth, then by definition, Earth is extraordinary. The fact that so many people assume sharing a galaxy or universe with other industrial peoples is more extraordinary than us being unique boggles my mind. I think it requires using anthro-nonpareilism as a first principle rather than an actual model for abiogenesis and evolution.

            There is a clear link between the rarity of an outcome and the mechanics that generate that outcome. Shuffling and dealing a deck of 52 cards will generate outcomes with greater ‘absolute’ rarity than a deck of 51 cards. Hydrogen is more common than plutonium because producing hydrogen requires fewer processes. In the context of Occam’s razor, we should be willing to carve into the mechanics of abiogenesis and evolution until it is no more complex than necessary to explain us.

            That being said, I can understand the emotions behind an astronomer’s statement that they are happy to be done with aliens. The environment of ETI hypothesis is a difficult environment to navigate. A serious scientist would need share that environment with a sensationalist media, a public as likely to caricature the scientific method as understand it, enthusiasts unwilling to respond to evidence, etc. I think most astronomers would be happy to discover an alien super project. I just don’t think they want all the crap that goes with looking.

      • Ashley Baldwin January 7, 2018, 10:29

        I disagree.

        I think the entire astronomy nee science community would be besides themselves if unequivocable evidence of ANY extraterrestrial life could be found let alone intelligent life. As a highly skeptical academic I know it’s how I feel. The greatest single discovery in human history and immensely reassuring to finally have evidence that we were not alone in an awfully large universe ( how tawdry and depressing that would be )! . However , extraordinary claims DO require extraordinary evidence . By it’s very nature science must be conservative and all findings falsifiable .

        Ironically I think the very reason that the KIC8462852 group have got themselves into such a terrible tizzy here is BECAUSE there WAS initial consideration given , however fancifully and brief, that the star might indeed harbour some form of technological artefact . That has subsequently been eroded by sober analysis and robust evidence to the contrary such that they have been left with no where to go other than increasingly speculative ( and frankly dull) explanations of an erstwhile external occulter in the absence of alien mega structure . I would guess that this is a downside to the crowd sourced research funding here given that an alien megastructure concept was perhaps ever so slightly and unconsciously dangled as a tacit incentive.

        A weakness of the entire scientific process is the “positive publication ” bias – whereby negative research results ,though equally important ,don’t make great Press and thus don’t get published as much by science journals . These have to make money like any periodical by selling copy and resulting advertising space . This has happened with KIC8462852. The researchers have put themselves under pressure to deliver the most positive result they can within the data set available . However far fetched. “Dull as dishwater” could equally well read as “dull as dust” though. Something to be wary of in future crowd funded studies .

        Though natural , some form of previously unknown stellar variable is actually not just a much better explanation than dust ,of any type ,but also a far more exciting one . You could even make as good or even better ( but still far fetched ) case for it being evidence of some form of alien technology – if you could build a Dyson Sphere around a star I’m sure you would also possess the ability to tinker with the star too.

        Regardless, Tabby’s star remains “a paradox wrapped in an enigma”

        • Michael Fidler January 7, 2018, 23:57

          The one good thing about all this is that a much larger segment of the populace are made aware of the concept of mega-structures and Dyson Spheres. The chance of the earth being impacted by an asteroid has made a lot of press which is now seen in the tabloids regularly, so the concept is not seen as outrages as it was just 25 years ago. I will never forget after giving a lecture to a group just after the New Horizon flyby of Pluto a lady asked me what about the astronauts on the mission? It kind of gives you perspective on just how few people even really understand or care about such subjects as they go thru there daily lives.
          The one thing about finding extraterrestrial life is that the whole community of Astronomers and Space explorations will have job security till Kingdom come.

          • ljk January 8, 2018, 14:42

            Late night talk show host Jimmy Kimmel does a segment where he interviews people on the street about recent news events but adds a twist to them to see if people catch the lie or not.

            In 2015 he did a segment after New Horizons flew by Pluto and asked random passerbys if they had heard that America had landed astronauts on Pluto! Of the ten people shown on the program, only one corrected the “reporter”. The rest either just agreed with the statement or went into elaboration, including one who mentioned the dog that went on the trip!

            It is an uphill battle, folks, and yes, we space buffs all need to be advocated and educations in addition to engineers, scientists, etc. The above just shows that having high technology and instant information access does not equal a better educated public.

            • ljk January 8, 2018, 14:44

              Advocates and educators. This is why I wish this blog had an edit feature, especially when I am typing too fast. :^)

        • ljk January 8, 2018, 14:48

          Ashley Baldwin said the following:

          “I think the entire astronomy nee science community would be besides themselves if unequivocable evidence of ANY extraterrestrial life could be found let alone intelligent life. As a highly skeptical academic I know it’s how I feel.”

          To be more accurate, the science community will embrace and celebrate the unequivocal discovery of alien life only after someone else has done it, probably while risking their professional reputations along the way.

          There is that old saying about a scientific discovery that goes from a professional first saying it’s a bunch of nonsense to finally declaring “I though of it first!” :^)

    • ljk January 4, 2018, 12:42

      I still think humanity is like an ant colony in the middle of a human construction site when it comes to dwelling in the galaxy. We don’t really know what we are looking at or comprehend the reality all around us, especially if it contains artificial features.

  • David Herne January 3, 2018, 23:14

    I haven’t read the paper yet and am interested in the specific spectral characteristics that have been measured. However, much deeper blue end of the spectrum attenuation versus less red end of the spectrum attenuation would not be surprising if energy collection by an alien megastructure was based principally on the photoelectric effect. We don’t have to think in terms of completely opaque structures do we?

  • James Franklin January 4, 2018, 8:23

    Whilst an artificial cause would be the most exciting, what a way to prove we are not alone, eventually it was clear that a new natural cause was the most likely.

    Interestingly the conversation regarding the magnetic activity of the star is intrigueing, and intetestingly, may not rule out dust. It is possible for the material orbiting tbe star to become ionised as a result of both the solar wind charged particle but also the varying magnetic activity. If parts of the material orbiting the star did/do become ionised then they would interact with the magnetic field of the star. Depending on the axis the field has in relation to Earth we could have a viable mechanism for some, though likely not all, of the strange behaviour we observe.

  • Ronald January 4, 2018, 10:11

    Happy, healthy and successful new year to all! And in particular to Paul and CD, keep up the good work! May this be a year of great discoveries.

    • Paul Gilster January 4, 2018, 12:42

      The same good wishes to you, my friend. I’m sure 2018 will not disappoint us when it comes to new discoveries!

  • Robert Feyerharm January 4, 2018, 10:22

    Are we certain the dust (if it is dust) obscuring Tabby’s Star is circumstellar? Could it be an interstellar dust cloud?

    • DJ Kaplan January 4, 2018, 15:30

      It’s a good point. There could be something that happens to be between us and the star. I think its proximity to the star is an assumption?

    • Ron S. January 5, 2018, 11:03

      Unlikely. An unbound object/cloud/swarm would make exactly one pass, whereas what we see here is an irregular periodicity. An intervening cloud with suitable characteristics would have to be exceptionally, even impossibly large and dense. It would almost certainly be visible on its own without Tabby’s Star as a back light.

  • Anton M. January 4, 2018, 12:49

    I am a bit on the fence if one should really consider it a theoretically possible ETI phenomena. The distance from Tabby’s is laughable. Should anyone be building megastructures there, they would have been all over the place with other exciting stuff – signals, spaceship trails, energy signatures etc. It would be a real Kardashev Type II, for Fermi’s sake! On the other hand, it is hard to believe in one-in-a-Galaxy odd star. For example, the main point about the natural cause in pulsar discovery was the multitude of the objects. Now we have something odd and in the only case and we know that Nature repeats itself – supernovas, GRBs, planet systems – particularly with such a banal globe of hot matter like a star. Or maybe it is a very special star and we still do not know a thing about the star variability in general, like Ashley wrote.

    • Ron S. January 4, 2018, 13:26

      Finding one is not evidence of uniqueness. Think about it.

      • ljk January 4, 2018, 15:36

        Bingo! Kepler’s original mission was to examine a very small slice of sky in the Cygnus constellation region for exoplanets. That it happened to come across Tabby’s Star from such a rather small cosmic sampling means we either got very lucky or objects like TS are not uncommon and we just haven’t been looking long or hard enough for them.

        Think of the very recent discovery of our interstellar visitor ‘Oumuamua in comparison. Astronomers are saying that now that we have the technological capability to detect objects approaching from other star systems we may find between one and ten of them every year, but of course the reality or falsehood of that possibility remains to be seen. It is still far from unlikely that something like ‘Oumuamua is not common to the Sol system or that such things are happening in the other 400 billion star systems of the Milky Way galaxy – unless a lot of big pointy rocks are being flung violently out of their systems into interstellar space all the time.

        Whether TS or ‘Oumuamua, we are just learning about them. They may be unusual only because we are so new at this game called astronomical science. It still boggles my mind that only in the 1920s did professional astronomers finally accept the reality that the Milky Way was not the entire Universe but just one of billions of galaxies throughout space.


        • Michael Fidler January 5, 2018, 10:13

          Linear vs. Non-Linear Thinking.

          Science has a tendency to work in a very linear manner until something very disruptive comes along and then jumps into a nonlinear mode of chaos and the outcome is a quantum leap to a new level of understanding. Very similar to Wars which is why prediction is used in both cases, with science fiction being the best at nonlinear concepts.


          Assuming the dwarfs have a median age of about 5 billion years, that means each has accumulated about 1% of the Earth’s mass worth of asteroidal material over their lifetimes. But that in turn means that anywhere from 10–100% of the Earth’s mass worth of rocks were ejected into interstellar space due this same process by each white dwarf!


          Ejection of material –“Jurads” — from post main sequence planetary systems
          Brad Hansen, Ben Zuckerman
          (Submitted on 19 Dec 2017)
          We show that the rate of pollution of white dwarfs by asteroidal material implies a concomitant rate of material ejection that can contribute significantly to the population of interstellar minor bodies. We note also that the irradiation during post main sequence evolution implies that much of this ejected material may lose volatiles, providing a rationale for the curious properties of the recently discovered interstellar object Oumuamua.


          Going back to the White Dwarf/Dyson Sphere Nemesis concept, the original star or even the possibility of a binary Nemesis star, would of left a signature in our solar system. The Late Great Bombardment 4 to 3.8 billion years ago could of been caused by the explosion of an early A class star (A1-A2) that had evolved into the red giant phase. This would be the correct time for it to have evolved into the red giant phase when the original Sun-Nemesis binary system developed 4.5 billion years ago. Another possibility is that a close binary A class Nemesis star system would eventual end up becoming a stable super-Chandrasekhar White Dwarf of up to 2.6 mass of the sun.
          There should be many indicators of this but the earth’s plate tectonics was one of the probable outcomes of The Late Great Bombardment so much of the radioactive geologic tracers may of been mix into the lower mantle.

          The Goddess of Nemesis Reigns Over Us…….

          • Harold Shaw January 5, 2018, 14:27

            Thank you for that ‘Oumaumau link. The only other hypothesis I had seen, put the ejection mechanism during planetary formation.

          • Michael Fidler January 7, 2018, 4:14

            Have been doing some calculations on the 26 million year orbital period of Nemesis and found that it moves only .05 arc second per year if in a circular orbit. This would take 20 years to show a movement of 1 arc second, the National Geographic Society – Palomar Observatory Sky Survey from the 1950’s compared to current surveys does not have enough resolution. The Dyson Sphere would only cover up stars or possibly gravitational lens nearby stars along its path. The current thinking is that Nemesis is at its most distant point from the Sun so it would probably not show up until a 100 years. In that time it may of covered 2.5 arc second in the sky and may be visible by blocking light from 2 separate stars, if the survey telescopes had that high of a resolution. If it was transferring the Milky way the stars are close enough together that it may dim two stars as it passes because the two would be merged on the photo plate.

            Since the assumption is that any advanced civilizations that built such an object would have no problem in covering up its electromagnetic signature. The only way to detect it would be if the Dyson Sphere was covering stars or the central white dwarf creating a gravitational lens, but we would have to know were to look in order to have high enough resolution to observe it. (Hubble Space Telescope)

            One other way is that the may make a dump of energy to regulate the sphere and this would most likely show up in the IR, but then you would be needing to be looking in the right place at the right time.

            Hmm, could be but moving to fast:

            ALMA: Interesting Objects in the Outer System



            Did they ever find out what these objects were, Glitch?

            • Michael Fidler January 8, 2018, 7:34

              Since this Dyson Sphere may only be 2 to 3 light years away from the Sun, it should be picked up by the GAIA mission thru astrometric microlensing. The problem is that the object is not visible, so machine learning (AI) would have to go thru the whole database looking for such an object. This would be a good project for Zooniverse with home personal computers that have NVIDIA’s newest Titan V GPU.

              Astrometric Microlensing with the GAIA satellite.

              GAIA is the “super-Hipparcos” survey satellite selected as a Cornerstone 6 mission by the European Space Agency. GAIA can measure microlensing by the small excursions of the light centroid that occur during events. The all-sky source-averaged astrometric microlensing optical depth is about 10^{-5}. Some 25000 sources will have a significant variation of the centroid shift, together with a closest approach, during the lifetime of the mission. A covariance analysis is used to study the propagation of errors and the estimation of parameters from realistic sampling of the GAIA datastream of transits in the along-scan direction during microlensing events. Monte Carlo simulations are used to study the 2500 events for which the mass can be recovered with an error of less than 50 per cent. These high quality events are dominated by disk lenses within a few tens of parsecs and source stars within a few hundred parsecs. We show that the local mass function can be recovered from the high quality sample to good accuracy. GAIA is the first instrument with the capabilities of measuring the mass locally in very faint objects like black holes and very cool white and brown dwarfs. For only 5 per cent of all astrometric events will GAIA record even one photometric datapoint. There is a need for a dedicated telescope that densely samples the Galactic Centre and spiral arms, as this can improve the accuracy of parameter estimation by a factor of about 10.


              Found another project that could go much further then GAIA, “Theia: Faint objects in motion or the new astrometry frontier”. This is an ESA M5 project using a high resolution space telescope in the 32 inch (o.8 meter) range, not to be confused with the 4 meter Telescope for Habitable Exoplanets with the Star Shade!

              Theia: Faint objects in motion or the new astrometry frontier.
              The Theia Collaboration ∗
              July 6, 2017
              In the context of the ESA M5 (medium mission) call we proposed a new satellite mission, Theia, based on relative astrometry and extreme precision to study the motion of very faint objects in the Universe. Theia is primarily designed to study the local dark matter properties, the existence of Earth-like exoplanets in our nearest star systems and the physics of compact objects. Furthermore, about 15 % of the mission time was dedicated to an open observatory for the wider community to propose complementary science cases. With its unique metrology system and “point and stare” strategy, Theia’s precision would have reached the sub micro-arcsecond level. This is about 1000 times better than ESA/Gaia’s accuracy for the brightest objects and represents a factor 10-30 improvement for the faintest stars (depending on the exact observational program). In the version submitted to ESA, we proposed an optical (350-1000nm) on-axis TMA telescope. Due to ESA Technology readiness level, the camera’s focal plane
              would have been made of CCD detectors but we anticipated an upgrade with CMOS detectors. Photometric measurements would have been performed during slew time and stabilisation phases needed for reaching the required astrometric precision.


              Waiting for the Gaia Data Release 2 (April 2018).

              • Ashley Baldwin January 8, 2018, 13:58

                Gaia is expected to find tens of thousands of Jupiter – Saturn mass planets via its astrometry ,with atleast 1000 of these within 100 light years. This extends down to Neptune mass within 26 light years . However this will require the full data set to be released five years after primary mission end ,in 2023 . Then hopefully more and with greater precision if the mission is extended to 9-10 years, consumables allowing .

              • ljk January 8, 2018, 14:55

                An advanced ETI would have little trouble hiding even large objects from humanity, in no small part because most of our species would not recognize an astronomical object as artificial, while the professionals who could would naturally place it in the Natural Until Proven Otherwise box – and yes I know there is good reason for that, I am just pointing out why it would be rather easy to hide from us.

                Perhaps what would be the real blow to our collective egos is an alien civilization that could not care less if we know about them or not. Or do not even recognize us as fellow intelligent beings.

                • Michael Fidler January 9, 2018, 10:55

                  I would say they are more worried about a gang of thugs seeing their house all lit up and advertising how much knowledge and high tech they have. Paranoia strikes deep, to have survived for so long they would definitely be very careful!

                  • ljk January 9, 2018, 12:38

                    If ETI were hiding, say, in the Planetoid Belt, and they felt that humans would somehow be a threat to them, all they would have to do is attach a rocket motor with a guidance computer to particular planetoids and then aim them at our main population centers.

                    I am not advocating such an action, I am only trying to point out that aliens having the ultimate high ground could rather easily defend themselves against humanity without the need for hi-tech weaponry or the usual nonsense we often see in most SF films about alien invaders.

                    Despite several decades of talking about it, we still cannot mount a sufficient defense in time in case someone did lob some big space rocks at Earth. Unless the military already has some kind of secret missile defense system already in orbit?

              • Michael Fidler January 12, 2018, 10:18

                Of course this may make it much harder to detect, especially if they could cloak the Gravitational microlensing:

                Are Cloaking Devices Coming? Metalens-Shaped Light May Lead The Way.


                Using Plasma for Cloaking would make sense for a large Dyson Sphere:

                Size validity of plasma-metamaterial cloaking monitored by scattering wave in finite-difference time-domain method.

                Limitation of the cloak-size reduction is investigated numerically by a finite-difference time-domain (FDTD) method. A metallic pole that imitates an antenna is cloaked with an anisotropic and parameter-gradient medium against electromagnetic-wave propagation in microwave range. The cloaking structure is a metamaterial submerged in a plasma confined in a vacuum chamber made of glass. The smooth-permittivity plasma can be compressed in the radial direction, which enables us to decrease the size of the cloak. Theoretical analysis is performed numerically by comparing scattering waves in various cases; there exists a high reduction of the scattering wave when the radius of the cloak is larger than a quarter of one wavelength. This result indicates that the required size of the cloaking layer is more than an object scale in the Rayleigh scattering regime”.



                • Michael Fidler January 12, 2018, 10:56

                  Here is an older article that makes sense but is very similar to the Scientist that said we can not go to the Moon in the early 20th century because rockets where not fast enough! (Before the concept of multi staged rockets)

                  Are we surrounded by Dyson Spheres?

                  “In this week’s “Ask a Physicist,” we’ll explore an awesome mash-up of exoplanets, supercivilizations, and dark matter, and try to figure out whether the “missing mass” in the universe is really advanced aliens with a cloaking device”.


                  Sounds good but what if they make it out of carbon-graphene and what if the universe is small bangs infinite, not big bang? (Halton Arp)

                  You can’t see the forest because of the trees.

                  “Even if the spheres themselves were extremely lightweight, and made up less than 1% of the total mass of their stars, that’s way more of the metals than actually exist in the universe”.

                  They use to call it Magic;-)

  • ljk January 4, 2018, 13:53

    Did “we” really know this day was coming, as the title of the Universe Today news item on Tabby’s Star shown below insists?

    Seems more like another bit of evidence that a wide range of people inhabiting Sol 3 really don’t want there to be aliens for a wide variety of reasons.

    You Knew This Day Was Coming. Alien Megastructures Ruled Out for Tabby’s Star. Dust is the Culprit – Universe Today


    The Universe is incredibly vast and ancient, making our species and planet less than microscopic specks in physical comparison. But that can be avoided and controlled so long as humans don’t look up too much (plus light pollution is getting rid of those pesky twinkling bright points) or bother to learn what science has found out in the last few centuries. There is a bit of dialogue in George Orwell’s 1948 novel 1984 about how easily Big Brother can change the states and distances of the stars or blot them out completely so far as the human mind is concerned which reminds me of our current real situation and doesn’t seem as implausible as it might on the surface of it. Many already willfully avoid learning about the world past their immediate tribal regions.

    However, the detection of or contact from an actual ETI will really upset the cultural apple cart and force humanity to confront what most thinking people have suspected for ages, that we are hardly the only intelligent life forms in the Universe.

    Modern people may think they are ready for real aliens, but I think the dialogue in this bit from the 1997 SF film Men in Black sums up the situation quite nicely:


    • Harold Shaw January 5, 2018, 14:53

      Don’t be so discouraged. I now feel terrible about my flippant response to you in the last post discussing METI. If there are other peoples out there, they can not hide indefinitely and even the stuck-in-their box astronomer is working towards revealing them.

      The greater public does not have to embrace the probability of ETIs. Looking at the motivation of flat Earthers, there are some who will always use the assumption of uniqueness as their first principle. (Insert less than civil response here.) They haven’t stopped astronomy from progressing. Within my lifetime, I went from being ridiculed for insisting that a theory that describes the formation of our Solar system predicts the formation of planetary systems around other stars to being uncomfortably steered to other topics when I insist that a theory describing abiogenesis and evolution on Earth predicts it happening on other planets. That is progress.

      • ljk January 8, 2018, 15:22

        Thank you, Harold, I appreciate that. As I pointed out before in that other thread, it is not that I want humanity to go broadcasting any old thing into the galaxy without regard for who or what may be out there.

        I am actually quite the advocate for placing information packages on all of our deep space vessels in the event that they are one day found by other intelligences who would undoubtedly appreciate knowing who their otherwise unannounced visitor is – especially the fact that it is not an intentional threat to them. Show me the scientist who would not have been grateful if ‘Oumuamua had been in fact an alien probe that its makers had included some kind of data storage with details on the probe, its mission, who made it, and why.

        That is one reason I was and am still unhappy with the lackluster effort regarding an information package on the New Horizons probe. If nothing else, all that mission team had to do was reproduce the Pioneer Plaque and bolt it on their vessel. Heck, they would not even have had to change the diagrams of the probe on the plaque and they could have certainly left Pluto in the original planetary lineup!

        What I was trying to say about broadcast METI is that we cannot control everyone with a transmitter even if we could. As I have said multiple times here, if China wanted to use their giant FAST radio telescope to transmit into the galaxy, who is going to stop them? They have already made it official that one of the purposes for their brand new astronomical observatory is to be the first nation to have the first successful SETI effort. As a result, could METI be far behind as an “enhancer”?

        This does not mean we should not debate the issue or come up with a series of formal message plans. They are both important and necessary. What must not be ignored is that there are many people and groups who will transmit into deep space and instead of turning into a bunch of totalitarian thugs, we should prepare for potential visitors and outcomes now that we are aware of the possibilities rather than think we can hide from the Universe.

    • hiro January 5, 2018, 22:00

      “They” hide in the Shapley Concentration, there is zero proof one way or the other. There is a big difference between being alone in this galaxy and being alone in this universe, the latter might imply that we live inside an universal quantum computer simulation. On the other hand, the former gives some basic info about life is quite rare in a galaxy but it says nothing about distribution of life in superclusters.

  • Greg Matloff January 4, 2018, 16:58

    Dear Paul
    The comments are are fascinating as the paper. My problem with the dust hypothesis is EM radiation pressure from the star. I suspect that ~1 micron dust particles will be blown out of the system rather rapidly unless there is
    an operating dust source orbiting the star. And would dust clumps yield the apparent repeatability in the dips? This star is truly amazing, whatever the explanation.
    Happy New Year to All, GREG

    • Paul Gilster January 4, 2018, 22:18

      Happy New Year to you and C, Greg, and thanks for being a continuing inspiration in this work!

    • Ashley Baldwin January 7, 2018, 10:40

      I certainly agree. Goodness knows how much UV alone the star is throwing out . If it is ,as the data hints , a potent and chaotic magnetic star it is also likely to be pushing out copious higher energy EM too. It’s rotation rate and mass lie very near to the transition to a late A type star.

  • Harold Daughety January 4, 2018, 21:21

    In every mention of aliens that I have seen, the only basic difference to humans seems to be in body shape. They apparently have the same ideas as humans – do they call their megastructure a Dyson Sphere, I wonder? I did a little thought construction of an alien race and came up with something similar to honeybees. Most of the individuals are sexless, and breeders live in a cloistered environment. Reproduction is on a replacement basis. They have their work, mostly manual, and their arts. I tried to think of a story plot, but decided they are so alien and so boring it was not worth the effort. Our human civilizations have always been xenophobic and that has led to the destruction of entire cultures. Hey, people, ET is not us and doesn’t think like we do!

    • DJ Kaplan January 5, 2018, 14:56

      Agreed. I like to refer to that as the Rubber-Forehead Alien problem. People seem to have trouble understanding the meaning of “alien”. Whatever is out there, we have to be ready for it to violate every one of our definitions.

      • ljk January 8, 2018, 15:01

        Blame decades of bad science fiction films and television series, especially those with low budgets for FX.

  • Coacervate January 6, 2018, 9:03

    I wonder if the dust explanation will hold when the next 20% dip repeats…if it repeats

    • ljk January 8, 2018, 14:58

      It ain’t over til it’s over, as Yogi Berra may or may not have once said.

  • David S. F. Portree January 6, 2018, 12:46

    The Tabby’s Star data might be evidence for one or more new natural phenomena, or for known phenomena acting together in an unusual way, or for known and new natural phenomena working together, or we might have caught a common but short-lived natural event “in the act.” Take your pick. Declaring that what we are observing there “rules out aliens” at this early stage is, however, unscientific. There is enough that is unusual about this star, and enough “wild ideas” out there for advanced space technology and advanced species behavior, that we cannot rule out anything even now.

    This is not a desperate attempt to salvage the “it’s aliens!” hypothesis. Rather, it’s an attempt to wave the little flag of humility. We don’t know everything. At the same time, we can be very pleased of ourselves for finding Tabby’s Star and mustering a big crowd-funded international effort to understand it. Though I think the conclusion reached so far is not as iron-clad as it seems, the fact that we can at short notice focus so much effort on a distant blinky star found through a volunteer effort makes me proud to be human.

  • ljk January 8, 2018, 17:29

    A Brief History of the Big Dumb Object Story in Science Fiction

    James Davis Nicoll

    Mon Jan 8, 2018 at 12:00 pm

    I was recently reminded of the golden age of Big Dumb Object stories (hat tip to reviewer Roz Kaveny for coining the phrase). As this is not yet commonly accepted genre shorthand, perhaps a definition is in order.

    Contrary to the name, BDOs are not necessarily dumb. In fact, most of them have rather sophisticated infrastructure working away off-stage preventing the story from being a Giant Agglomeration of Useless Scrap story. What they definitely are is large.

    To be a BDO, the Object needs to be world-sized, at least the volume of a moon and preferably much larger. BDOs are also artificial. Some…well, one that I can think of but probably there are others…skirt the issue by being living artifacts but even there, they exist because some being took steps to bring them into existence.

    There may be another characteristic BDOs need to have to be considered a classic BDO: absent creators and a consequently mysterious purpose. At the very least, by the time the story begins, the BDO has been around for a long time1. If there’s an example of a story about the construction of a BDO, I cannot think of it. Have fun pointing out the well-known books I have forgotten in comments!

    Full article online here:


    To quote:

    One detail about BDOs that has puzzled me for some time is the incredible lack of women writing them. There’s nothing intrinsic to the concept that shouts “dude!” to me and yet, for some reason I’ve either never encountered a BDO book by a woman or I managed to forget its existence. If you know of any examples, please do point them out to me in comments.

    • Michael Fidler January 8, 2018, 23:24

      Three of my favorites are;

      “EON” by Greg Bear.
      Shades of `Oumuamua.

      “Titan” by John Varley.
      Could Titan be hollow?

      “The Architects of Hyperspace” by Thomas R. McDonough.
      Around a neutron star, no less!
      Tom McDonough was the SETI Coordinator for The Planetary Society.

  • ljk January 10, 2018, 13:14

    Today’s Top Space Headline: “Most Scientists in the ‘Never Aliens’ Camp Desperately Want to be Convinced Otherwise”


  • ljk January 10, 2018, 14:53

    As I said before, for some astronomers aliens are just too messy to deal with. However, this is 2018, not 1948. Attitudes have changed and information/new are available at the literal push of a button. The professional community needs to get up to speed/date with the way they disseminate their knowledge and findings to the general public and politicians, or what we saw in 2017 regarding aliens is just a taste of things to come.

    See here:


    To quote:

    “Currently, most SETI-related news seems to be interfering with conventional scientific discoveries, stealing the limelight—without following basic rules of science,” wrote Dutch exoplanet researcher Ignas Snellen of Leiden Observatory, on a Facebook exoplanets discussion group for professional astronomers.

    Although he has “great respect for SETI scientists,” Leiden wrote, “there is no place for alien civilizations in a scientific discussion on new astrophysical phenomena, in the same way as there is no place for divine intervention as a possible solution. One may view it as harmless fun, but I see parallels in athletes taking banned substances. It may lead to short-term fame and medals, but in the long run it harms the sport. Same for astronomy: we should be very careful not to be ridiculed. I really hope we can stop mentioning SETI for every unexplained phenomenon.”

    Anyone, professional or otherwise, who thinks that the real discovery of alien life – be it microbes or signals or spaceships or megastructures – isn’t going to be one heck of a mess when it happens is going to be in for a rude awakening. Hiding under their beds or sticking their heads in the sand isn’t going to change that, except perhaps to make the most important discovery ever possibly worse.

  • Harry R Ray January 12, 2018, 11:54

    One way to POSSIBLY tell if a phemonenon is natural or non-natural is by IRRECONCILABLE DATA SETS! If one “observer” at one specific time records data which is COMPLETELY CONTRARY to another “observer’s” data taken in a DIFFERENT time frame and no scientific framework for reconcilliation can be agreed upon, it might mean that ETI is able to “produce” different CAUSES at different times as a means to communicate their presence to others. We MAY(be VERY VERY cautious here before we race to ANY conclusions) have such a situation with Boyajian’s Star. Michael Castelanz data-mined plates at the Martha Mitchell Observatory and came to the conclusion that Bradley Schaffer’s century long dimming claim is correct. The Sonneborg Sky Patrol plates show completely otherwise. It is URGENT that we find out why these data sets SEEM to be irrecincilable and which is ACTUALLY the case.

    • Harry R Ray January 14, 2018, 14:47

      This COULD be the MOST BIZARRE firm of this I have ever come across! arxiv.org/abs/1801.03585. At the moment, I don’t even have a TAKE on this.

      • ljk January 15, 2018, 10:19


        Indications of an unexpected signal associated with the GW170817 binary neutron star inspiral

        E. Fischbach, V. E. Barnes, N. Cinko, J. Heim, H. B. Kaplan, D. E. Krause, J. R. Leeman, S. A. Mathews, M. J. Mueterthies, D. Neff, M. Pattermann

        (Submitted on 10 Jan 2018)

        We report experimental evidence at the 2.5σ level for an unexpected signal associated with the GW170817 binary neutron star inspiral. This evidence derives from a laboratory experiment simultaneously measuring the β -decay rates of Si-32 and Cl-36 in a common detector. Whereas the Si-32 and Cl-36 decay rates show no statistical correlation before or after the inspiral, they are highly correlated (∼95% ) in the 5 hour time interval immediately following the inspiral.

        If we interpret this correlation as arising from the influence of particles emitted during the inspiral, then we can estimate the mass m x of these particles from the time delay between the gravity-wave signal and a peak in the β -decay data. We find for particles of energy 10 MeV, m x ≲ 16 eV which includes the neutrino mass region m ν ≲ 2 eV. The latter is based on existing limits for the masses m i of the three known neutrino flavors.

        Additionally, we find that the correlation is even stronger if we include data in the 80 minute period before the arrival of the gravity wave signal.

        Given the large number of radionuclides whose decays are being monitored at any given time, we conjecture that other groups may also be in a position to search for statistically suggestive fluctuations of radionuclide decay rates associated with the GW170817 inspiral.

        Comments: 13 pages, 3 figures
        Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics – Phenomenology (hep-ph)
        Cite as: arXiv:1801.03585 [astro-ph.HE]
        (or arXiv:1801.03585v1 [astro-ph.HE] for this version)

        Submission history

        From: Dennis E. Krause [view email]

        [v1] Wed, 10 Jan 2018 23:38:03 GMT (2844kb,D)


        • Michael Fidler January 18, 2018, 9:30

          Just remembered the first Science Fiction novel that I read was “Orphans of the Sky” by Robert A. Heinlein, one of the earliest fictional depictions of a “generation ship.” The ship was part of the “Proxima Centauri Expedition, I had no idea that it was written in 1941!

        • Harry R Ray January 19, 2018, 10:53

          The distance to NGC4993 has been RECENTLY CONFIRMED to be 130 light years. Since the GRB jet was NOT POINTED AT US, the DISPERSION of particles would NOT be CONCENTRATED, and any particles reaching the lab experiments would be EXTREMELY DIFFUSE! It seems to me that the gravity waves THEMSELVES may be responsible, and that this may well be BY FAR THE CLOSEST GW event of this magnitude in the past century, and the reason why this kind of result was never produced PRIOR to this one in past similar lab experiments.

  • Michael Fidler January 14, 2018, 2:12

    There are many examples of stars doing unusual things, this is a prime example of something nearby that may be similar to KIC 8462852.

    Sirius: The brightest star in our sky was once red!

    The alien laser sounds very enticing but it is just probably dust and comets falling into Sirius itself or its white dwarf companion. Has ALMA taken a close look at this system, that may answer the question.

    Sirius, mystery of red color.

    Laser transmission from Sirius.

    Resolving the Red Controversy?

    THE TEAR OF SIRIUS──Color Change Mystery.

    Sirius Issues──Red Controversy.

    Solving the puzzle of “red” Sirius.

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