Planet Hunters Talk

An interesting paper that mentions KIC 8462852 and Planet Hunters

  • johnfairweather by johnfairweather

    Centauri Dreams


    What’s Next for Unusual KIC 8462852?
    Posted: 15 Oct 2015 06:58 AM PDT
    I want to revisit the paper on KIC 8462852 briefly this morning, as I’m increasingly fascinated with the astrophysics we’re digging into here. The fact that the star, some 1480 light years away, is also a candidate for further SETI investigation makes it all the more intriguing, but all my defaults lean toward natural processes, if highly interesting ones. Let’s think some more about what we could be looking at and why the ‘cometary’ hypothesis seems strongest.
    Remember that we’re looking at KIC 8462852 not only because the Kepler instrument took the relevant data, but because the Kepler team took advantage of crowdsourcing to create Planet Hunters, where interested parties could sign up to study the light curves of distant stars on their home computers. KIC 8462852 has been causing ripples since 2011 because while we do seem to be seeing something passing between its light and us, that something is not a planet but a large number of objects in motion around the star. Some of the dips in starlight are extremely deep (up to 22 percent), and they are not periodic.
    Here’s how Phil Plait describes the situation:
    …it turns out there are lots of these dips in the star’s light. Hundreds. And they don’t seem to be periodic at all. They have odd shapes to them, too. A planet blocking a star’s light will have a generally symmetric dip; the light fades a little, remains steady at that level, then goes back up later. The dip at 800 days in the KIC 8462852 data doesn’t do that; it drops slowly, then rises more rapidly. Another one at 1,500 days has a series of blips up and down inside the main dips. There’s also an apparent change in brightness that seems to go up and down roughly every 20 days for weeks, then disappears completely. It’s likely just random transits, but still. It’s bizarre.
    A ragged young debris disk would be the natural conclusion, but arguing against this is the fact that we don’t see the infrared excess that a dusty disk would create. I also got interested in what nearby objects might be doing to this star when I started digging into the paper, which is cited at the end of this piece. Yale postdoc Tabetha Boyajian and colleagues present an image from the UK Infrared telescope (UKIRT) that shows KIC 8462852 along with a second source of similar brightness, as shown in the image below. Notice the ‘extension’ of KIC 8462852 to the left.

    Image: UKIRT image for KIC 8462852 and another bright star for comparison, showing that it has a distinct protrusion to the left (east). For reference, the grid lines in the image are 1000 × 1000. Credit: Tabetha Boyajian et al.
    A follow-up Keck observation revealed what the UKIRT image suggested, that there is a faint companion star.

    Image: Keck AO H-band image for KIC 8462852 showing the companion was detected with a 200 separation and a magnitude difference ∆H = 3.8. Credit: Tabetha Boyajian et al..
    This gets important as we consider the cometary debris hypothesis. The paper argues that the chance alignment possibility is only about one percent. If the companion is at the same distant as KIC 8462852, which is an F-class star, then we would be looking at an M-class red dwarf, roughly 885 AU distant from its companion. From the paper:
    At this separation, the second star cannot currently be physically affecting the behavior of the Kepler target star, though could be affecting bodies in orbit around it via long term perturbations. If such a star is unbound from KIC 8462852, but traveling through the system perpendicular to our line of sight, it would take only 400 years to double its separation if traveling at 10 km sec−1. So, the passage would be relatively short-lived in astronomical terms.
    Recall that the paper settles on cometary activity as the most likely natural explanation for the unusual KIC 8462852 light curve. We could be looking at a series of comet fragments seen close to the star as they move on a highly eccentric orbit, a collection of objects that has spread around the orbit and may be continuing to fragment. And as seen yesterday, Boyajian and team make the case that both thermal stress and the presence of super-Earth planets orbiting within 1 AU of the star could account for the tidal disruption that would have produced this scenario.
    We’ve often discussed cometary disruptions in these pages, speculating on what the passage of a nearby star might do to comets in the Oort Cloud. As per the images above, it’s a natural speculation that the anomalies of KIC 8462852 are the result of a similar scenario. We have no idea whether the companion star is bound to KIC 8462852, but assume for a moment that it is not. A star passing close enough to this system has the potential for triggering a swarm of infalling comets. If the star is gravitationally bound, then we can invoke the so-called Kozai mechanism, ‘pumping up comet eccentricities,’ as the paper puts it. We can explore this hypothesis by studying the motion of the companion star to confirm its bound or unbound status.
    The paper, as we saw yesterday, explores other hypotheses but settles on comet activity as the likeliest, given the data we currently have. The kind of huge collision between planets that would produce this signature would also be rich in infrared because of the sheer amount of dust involved, and we don’t see that. You can see why all this would catch the eye of Jason Wright (Penn State), who studies SETI of the Dysonian kind, involving large structures observed from Earth. Because if we’re looking at cometary chunks, some of these are extraordinarily large.
    So what’s next? The paper explains:
    First and foremost, long-term photometric monitoring is imperative in order to catch future dipping events. It would be helpful to know whether observations reveal no further dips, or continued dips. If the dips continue, are they periodic? Do they change in size or shape? On one hand, the more dips the more problematic from the lack of IR emission perspective. Likewise, in the comet scenario there could be no further dips; the longer the dips persist in the light curve, the further around the orbit the fragments would have to have spread. The possibility of getting color information for the dips would also help determine the size of the obscuring dust.
    Monitoring of KIC 8462852 will continue from the ground thanks to the efforts of the MEarth project, which will begin the effort in the fall of this year, and that’s going to be useful for tracking the variability of the dips. Remember, too, that problem of lack of infrared excess. Those numbers could change if we really are witnessing a recent event. The paper continues:
    Several of the proposed scenarios are ruled out by the lack of observed IR excess but the comet scenario requires the least. However, if these are time-dependent phenomenon, there could be a detectable amount of IR emission if the system were observed today. In the comet scenario, the level of emission could vary quite rapidly in the near-IR as clumps pass through pericenter (and so while they are transiting). The WISE observations were made in Q5, so detecting IR-emission from the large impact scenario, assuming the impact occurred in Q8 is also a possibility. We acknowledge that a long-term monitoring in the IR would be demanding on current resources/facilities, but variations detected in the optical monitoring could trigger such effort to observe at the times of the dips.
    What a fascinating object! There has been a media flurry about the SETI possibilities, but that doesn’t mean that we shouldn’t investigate KIC 8462852 in SETI as well as astrophysical terms. No serious scientist is jumping to conclusions here other than to say that there is nothing in the laws of physics that would preclude the existence of civilizations more advanced than our own, and nothing that we know of that would keep us from detecting large artifacts. How they could be detected around other stars will be the subject of a forthcoming paper from Jason Wright and colleagues in The Astrophysical Journal, one we’ll obviously discuss here.
    The paper is Boyajian et al., “Planet Hunters X. KIC 8462852 – Where’s the flux?” submitted to Monthly Notices of the Royal Astronomical Society (preprint).

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  • johnfairweather by johnfairweather

    Original paper is here - http://arxiv.org/pdf/1509.03622v1.pdf

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  • amr2014 by amr2014

    Where i can Find KIC 8462852 Chart Link?

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  • jasondarnieder by jasondarnieder in response to amr2014's comment.

    I am looking for the same

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  • bubuntu59 by bubuntu59

    companion very close, 1000au, if same happened to companion,
    alien hypothesis possible

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  • CMEdwards by CMEdwards

    I read the paper. The hypothesis is a collection of thousands of objects, but they don't expressly say that the light curve shows this. If it did, I think the debate would have been shorter.

    The two occultations that most clearly are not planets (D800 and D1500) are unique in the Kepler data, but give the appearance that this "unique" event happened twice in the KIC 8462852 system. This isn't incompatible with the comet hypothesis, given the near 2:1 resonance between D800 and D1500.

    However, I can't resist the urge to point out that, while there aren't enough observations to nail down the orbits yet, there are allowed solutions with both collections of objects inside the habitable zone.

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  • johnfairweather by johnfairweather

    I was at a lecture last week, where the lecturer thought that parts of the light curve (which was shown) might be due to instrument problems.

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  • johnfairweather by johnfairweather

    Interesting follow-up paper - http://www.desdemonadespair.net/2015/10/did-kepler-space-telescope-discover.html

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  • planetsam by planetsam in response to JohnF.'s comment.

    That's not a follow-up paper, just someone selectively taking parts from a 2-year old paper and saying handwavingly "oh that looks a little bit like it, they must be the same". Notice they don't even appreciate the problem with multiple long-duration planetary transits...

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  • johnfairweather by johnfairweather

    Further Centauri Dreams article here -

    Back from my break, I have to explain to those who asked about what exotic destination I was headed for that I didn’t actually go anywhere (the South Pacific will have to wait). The break was from writing Centauri Dreams posts in order to concentrate on some other pressing matters that I had neglected for too long. Happily, I managed to get most of these taken care of, all the while keeping an eye on interstellar news and especially the interesting case of KIC 8462852 (for those just joining us, start with KIC 8462852: Cometary Origin of an Unusual Light Curve? and track the story through the next two entries).

    Whatever the explanation for what can only be described as a bizarre light curve from this star, KIC 8462852 is a significant object. While Dysonian SETI has been percolating along, ably studied by projects like Glimpsing Heat from Alien Technologies, the public has continued to see SETI largely in terms of radio and deliberate attempts to communicate. Tabetha Boyajian and team, who produced the first paper on KIC 8462852, have put an end to that, ensuring wide coverage of the object as well as the notion that detection of an extraterrestrial intelligence might occur through observing large artificial structures in our astronomical data.

    Meanwhile, the delightful ‘Tabby’s Star’ is beginning to emerge as a replacement for the star’s unwieldy designation. Coverage of the story has been all over the map. The term ‘alien megastructures’ has appeared in various headlines, while others have focused on the natural explanations that could mimic the ETI effect. The tension between natural and artificial is going to persist, and it’s the subject of Jason Wright and colleagues in their recent paper (submitted to The Astrophysical Journal), which asks that kinds of signatures an alien civilization’s activities could create, and what natural phenomenon could explain such signatures.

    I think the Wright paper hits exactly the right note in its conclusion:

    Invoking alien engineering to explain an anomalous astronomical phenomenon can be a perilous approach to science because it can lead to an “aliens of the gaps” fallacy (as discussed in §2.3 of Wright et al. 2014b) and unfalsifiable hypotheses. The conservative approach is therefore to initially ascr…

    Just so, and the lengthy discussions in the comments section here on the previous three articles on KIC 8462852 are much in that spirit. We do have the cometary hypothesis suggested in the original Boyajian paper as what had been considered the leading candidate, and Michael Million, a regular in these pages, has pointed to a paper from Jason Barnes (University of Idaho) and colleagues that looks at the phenomenon of gravity darkening and spin-orbit misalignment.

    In this scenario, we have a star that is spinning fast enough to become oblate; i.e., it has a larger radius at the equator than it does at the poles, producing higher temperatures and ‘brightening’ at the poles, while the equator is consequently darkened. The transits of a planet in this scenario can produce asymmetrical light curves, a process the Wright paper notes, and one that Million began to discuss as early as the 17th in the comments here. That discussion was picked up in Did the Kepler space telescope discover alien megastructures? The mystery of Tabby’s star solved, which appeared in a blog called Desdemona Despair. The author sees the case as clear-cut: “There are four discrete events in the Kepler data for KIC 8462852, and planetary transits across a gravity-darkened disk are plausible causes for all of them.”

    Screenshot from 2015-10-26 09:29:52

    Image: Effects of rapid rotation on the shape of stars. Credit: Ming Zhao (Penn State).

    Meanwhile, Centauri Dreams reader Jim Galasyn uncovered a paper by a team led by Shoya Kamiaka (University of Tokyo) studying gravity darkening of the light curves for the transiting system PTFO 8-8695, also studied by Barnes, which involves a ‘hot Jupiter’ orbiting a rapidly rotating pre-main-sequence star. Gravity darkening appears to be very much in play, and we can, as the Desdemona Despair blog does, cite the Barnes paper: “An oblique transit path across a gravity-darkened, oblate star leads to the long transit duration and asymmetric lightcurve evident in the photometric data [for the PTFO 8-8695 system].”

    In Wright et al.’s “Signatures and Information Content of Transiting Megastructures” paper, which looks in depth at the natural sources of unusual light curves, these possibilities are discussed in relation to non-spherical stars, and this is worth quoting:

    The dominant effect of a non-disk-like stellar aspect on transit light curves is to potentially generate an anomalous transit duration; the effects on ingress and egress shape are small. Gravity darkening, which makes the lower-gravity portions of the stellar disk dimmer than the other parts, can ha…

    Another effect of a non-spherical star is to induce precession in an eccentric orbit. Wright also takes note of PTFO 8-8695, “which exhibits asymmetric transits of variable depth, variable duration, and variable in-transit shape.” Here astronomers were helped by the star’s age, which was soundly established by its association with the Orion star forming region. Wright adds that effects of this magnitude would not be expected for older, more slowly rotating objects.

    The work on KIC 8462852 continues, and I also need to mention that the Allen Telescope Array focused in on this fascinating target beginning on October 16, even as the American Association of Variable Star Observers (AAVSO) published an Alert Notice requesting that astronomers begin observing the system. For more on this, see SETI Institute Undertakes Search for Alien Signal from Kepler Star KIC 8462852. Universe Today quotes the SETI Institute’s Gerald Harp as saying: “This is a special target. We’re using the scope to look at transmissions that would produce excess power over a range of wavelengths.” I’ll obviously be reporting on the paper that comes out of the ATA search.

    The papers discussed today are Wright et al., “The Ĝ Search for Extraterrestrial Civilizations with Large Energy Supplies. IV. The Signatures and Information Content of Transiting Megastructures,” submitted to The Astrophysical Journal (preprint); Barnes et al., “Measurement of Spin-Orbit Misalignment and Nodal Precession for the Planet around Pre-Main-Sequence Star PTFO 8-8695 From Gravity Darkening,” accepted at The Astrophysical Journal (preprint) and Kamiaka et al., “Revisiting a gravity-darkened and precessing planetary system PTFO 8-8695: spin-orbit non-synchronous case,” accepted at Publications of the Astronomical Society of Japan (preprint).

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  • johnfairweather by johnfairweather

    Another follow-up paper - http://mikegarrett.blogspot.nl/2015/10/another-hint-that-kepler-system.html?spref=fb

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  • CMEdwards by CMEdwards

    The Allen Telescope Array took a look at KIC 8462852 for two weeks at the end of October. They detected no narrow band radio signals above 180 Jy and no broadband signals above 100 Jy at frequencies between 1 GHz and 10 GHz. They scanned with a multiband filter in 8 MHz steps.

    Now, KIC 8462852 is 454 parsecs away. A signal that still has even 100 Jy power after that distance would need a big whopping transmitter. You couldn't even rule out our own planet at that distance with that sensitivity. However, they enable us to say two important things about the alien megastructure hypothesis.

    First, no one at Tabby's Star is deliberately trying to contact us on the monitored frequencies. Although a big transmitter would be required, it's not one beyond even our own capabilities, much less hypothetical people able to put rings around a star. So it's not unreasonable to assume that the reason we aren't seeing one is because it's absent.

    Second, this puts a limit on microwave emissions from Tabby's Star than can rule out some hypothetical astroengineering. They're not doing anything like system-wide microwave power transmission that leaks a lot at the monitored frequencies or we'd see that. (Remember, we're talking about a hypothetical astroengineering project. The capabilities needed to build such a thing exceed our own by a few orders of magnitude. They could get the power together to leak out a few petaWatts if that's what they wanted to do with their megastructure.)

    Does this rule out a megastructure? No. But it's not exactly the proof of one that I was hoping for, either.

    You can find their article at:

    http://arxiv.org/abs/1511.01606

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  • pcrumley by pcrumley

    In my opinion it rules the alien megastructure somewhat. However, they could be "chatting" softer than we can hear. I think its not an alien megastructure. Its probably a bigger than normal swarm of comets or debris.

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  • CMEdwards by CMEdwards

    In all fairness to probably nonexistant space aliens, a signal of 100 Janskies at 454 parsecs goes beyond anything necessary for simple communications inside their system. That is the best the ATA could do on short notice, but it's a little coarse.

    I don't think it's "comet clumps". The conditions necessary for comets to make this signal without an infrared contribution would be almost as miraculous a coincidence as space aliens.

    Yeah, I want it to be a megastructure, but what I should really be hoping for isn't space aliens. It's more data.

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  • johnfairweather by johnfairweather

    An update -

    Centauri Dreams


    A Cometary Solution for KIC 8462852?
    Posted: 25 Nov 2015 07:00 AM PST
    KIC 8462852 is back in the news. And despite a new paper dealing with the unusual star, I suspect it will be in the news for some time to come, for we’re a long way from finding out what is causing the unusual light curves the Planet Hunters group found in Kepler data. KIC 8462, you’ll recall, clearly showed something moving between us and the star, with options explored by Tabetha Boyajian, a Yale University postdoc, in a paper we examined here in October (see KIC 8462852: Cometary Origin of an Unusual Light Curve? and a series of follow-up articles).
    To recap, we’re seeing a light curve around this F3-class star that doesn’t look anything like a planetary transit, but is much more suggestive of debris. Finding a debris disk around a star is not in itself unusual, since we’ve found many such around young stars, but KIC 8462 doesn’t appear to be a young star when looked at kinematically. In other words, it’s not moving the way we would expect from a star that has recently formed. Moreover, the star shows us none of the emissions at mid-infrared wavelengths we would expect from a young, dusty disk.
    Jason Wright and the team at the Glimpsing Heat from Alien Technologies project at Penn State have taken a hard look at KIC 8462 and discussed it briefly in a recent paper (citations for both the Boyajian and Wright papers are at the end of this entry). It seems entirely reasonable to do what Wright did in referencing the fact that the light curve we see around the star is what we would expect to see if an advanced civilization were building something. That ‘something’ might be a project along the lines of a ‘Dyson swarm,’ in which huge collectors gather solar energy, or it could be a kind of structure beyond our current thinking.
    We all know that the media reaction was swift, and we saw some outlets acting as if Wright had declared KIC 8462 an alien outpost. He had done no such thing, nor has he or the Penn State team ever suggested anything more than continuing investigation of this strange star. What seems to bother others, who have scoffed at the idea of extraterrestrial engineering, is that Wright and company have not explicitly ruled it out as a matter of course. The assumption there is that no other civilizations exist, and therefore we could not possibly be seeing one.
    I come down on the side of keeping our options open and studying the data in front of us. We have a lot of work ahead to figure out what is causing a light curve so unusual that at least one of the objects briefly occulting this star caused a 22 percent dip in its flux. That implies a huge object, evidently transiting in company with many smaller ones. There seems to be no evidence that the objects are spherically symmetric. What’s going on around KIC 8462?
    A new paper from Massimo Marengo (Iowa State) and colleagues looks at what Tabetha Boyajian identified as the most likely natural cause of the KIC 8462 light curves. All I have at this point is the JPL news release and a release from Iowa State — the paper has not yet appeared online — describing evidence for a swarm of comets as the culprit. The study, which has been accepted at Astrophysical Journal Letters relies on Spitzer data dating from 2015, five years later than the WISE data that found no signs of an infrared excess.

    Image: This illustration shows a star behind a shattered comet. Is this the explanation for the unusual light curves found at KIC 8462852? Image credit: NASA/JPL-Caltech.
    If there had been a collision between planets or asteroids in this system, it was possible that the WISE (Wide-field Infrared Survey Explorer) data, taken in 2010, reflected conditions just before the collision occurred. Now, however, we can rule that out, because Spitzer, like WISE, finds no excess of infrared light from warm dust around KIC 8462. So the idea of planet or asteroid collisions seems even less likely. Marengo, according to the JPL document, falls back on the idea of a family of comets on an eccentric orbit. He’s also aware of just how odd KIC 8462 is:
    “This is a very strange star,” [Marengo] said. “It reminds me of when we first discovered pulsars. They were emitting odd signals nobody had ever seen before, and the first one discovered was named LGM-1 after ‘Little Green Men… We may not know yet what’s going on around this star, but that’s what makes it so interesting.”
    It would take a very large comet indeed to account for the drop in flux we’ve already seen, but a swarm of comets and fragments can’t be ruled out because we just don’t have enough data to make the call. I assume Marengo also gets into the fact that a nearby M-dwarf (less than 900 AU from KIC 8462, is a possible influence in disrupting the system. The comet explanation would be striking if confirmed because we have no other instances of transiting events like these, and we would have found these comets by just happening to see them at the right time in their presumably long and eccentric orbit around the star.

    Image: Left: a deep, isolated, asymmetric event in the Kepler data for KIC 8462. The deepest portion of the event is a couple of days long, but the long “tails” extend for over 10 days. Right: a complex series of events. The deepest event extends below 0.8, off the bottom of the figure. After Figure 1 of Boyajian et al. (2015). Credit: Wright et al.
    So, despite PR headlines like Strange Star Likely Swarmed by Comets, I think we have to take a more cautious view. We’re dealing with a curious star whose changes in flux we don’t yet understand, and we have candidate theories to explain them. We’re no more ready to declare comets the cause of KIC 8462’s anomalies than we are to confirm alien megastructures. At this point we should leave both natural and artificial causes in the mix and recognize how long it’s going to take to work out a viable solution through careful, unbiased analysis.
    The Marengo paper is Marengo, Hulsebus and Willis, ”KIC 8462852: The Infrared Flux,” Astrophysical Journal Letters, Vol. 814, No. 1 (abstract). I write about it this morning only because it is getting so much media attention — more later when I can go through the actual paper. The Boyajian paper is Boyajian et al., “Planet Hunters X. KIC 8462852 – Where’s the flux?” submitted to Monthly Notices of the Royal Astronomical Society (preprint). The Wright paper is Wright et al., “The Ĝ Search for Extraterrestrial Civilizations with Large Energy Supplies. IV. The Signatures and Information Content of Transiting Megastructures,” submitted to The Astrophysical Journal (preprint).

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  • johnfairweather by johnfairweather

    Another interesting paper - http://mikegarrett.blogspot.nl/2015/10/another-hint-that-kepler-system.html

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  • CMEdwards by CMEdwards in response to johnfairweather's comment.

    Marengo's analysis is comfortably sound as far as it goes. I'm also encouraged that he also includes an accounting for the 2.4 sigma infrared flux signal that came out of his model in spite of the 3.0 sigma cutoff for his hypothesis test, seeing as it's not uncommon for a small shortfall in a signal to go away in later, more precise measurements. So, his model result is still valid for either flux. However, if you read his infrared flux model description carefully, the model itself has a problem: he is specifically modeling dust; therefore, he can only conclusively eliminate dust. His model can't differentiate between two different causes with the same lack of dust.

    You can find the new paper at http://arxiv.org/abs/1511.07908.

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  • CMEdwards by CMEdwards

    It's a pity we missed it this year. If the frequency is roughly that of the published Fourier analysis, then the next big dip should occur in mid July to early August of 2017.

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  • johnfairweather by johnfairweather

    "Optical SETI Observations of the Anomalous Star KIC 8462852" - http://arxiv.org/abs/1512.02388v1 - Click on PDF link (RHS) for full paper.

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  • Dwight Huth by Dwight Huth

    ...but still how can comets or cometary debris cause a 15% dip in the light of KIC? The area covered by a swarm of comets would have to be immense giving that Jupiter would cause a 1% dip in the light of KIC. Jupiter is 6.696455938697318% the diameter of KIC at 139,822 km in diameter. I did some calculations and came up with 15% of KIC's diameter is 313,200 km in diameter which is a difference of 173,378 km in diameter compared to Jupiter.

    I just don't see a swarm of comets causing a 15% and more so a 22% dim in the light of KIC. A 22% dim in KIC caused by a transiting planet would make the object 459,360 km in diameter.

    I was also reading about Quantum Eraser.

    Is it possible to use the same process with Kepler to create a better resolution factor when viewing stars?

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  • CMEdwards by CMEdwards

    Part of the difficulty is that the system has no dust disk. However, in all other systems in which exocomets have been identified, a critical step of that detection process was identifying regular variations in the infrared spectrum of a dust disk. Thus, just as early detections of exoplanets were biased toward hot jupiters, early detections of exocomets have been biased toward young dusty stars. Those are the ones that are easiest to find.

    If KIC 8462852 really has comet clumps, it will be the first detection of comets around a star without significant detectable dust to give a background spectrum.

    So, if it's comets, what makes this star special?

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  • CMEdwards by CMEdwards

    This analysis might be another development: http://arxiv.org/abs/1601.03256

    According to this fellow, the star's magnitude has been fading over the past century of observations.

    However...

    He says Boyajian et al. performed the same check but arrived at a different answer. I'm not sure how that happened.

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  • johnfairweather by johnfairweather

    As I say elsewhere, someone then wrote a paper, about how long it would take to build a Dyson Sphere.

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  • CMEdwards by CMEdwards

    Just out of curiosity, while we're on the topic of astroengineering and stars that may or may not be fading, does anyone know what a Criswell Sun should theoretically look like? Does star lifting have a spectral signature?

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  • johnfairweather by johnfairweather

    Must confess, never heard of it, until now - https://en.wikipedia.org/wiki/Star_lifting

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  • CMEdwards by CMEdwards

    In other developments, there is a new analysis by Michael Hippke questioning Scaeffer's claim that the star in question has been fading in an unusual pattern over 100 years. That article can be found here: http://arxiv.org/abs/1601.07314

    Bradley Schaeffer has posted a response here: http://www.centauri-dreams.org/?p=34933

    In short, Hippke has claimed that the apparent fading reported by Schaeffer is most likely an artifact, probably due to a combination of instrument changes over the past century and some fairly large gaps in the dataset. Schaeffer counters that Hippke's analysis is insufficient because it doesn't exclude datapoints with known instrument changes that would in fact predictably magnify systematic errors and should be kicked out.

    In my opinion, Schaeffer has the better argument, but this makes twice now that other teams reported no significant variation. It would be nice to have someone repeat Schaeffer's result.

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  • johnfairweather by johnfairweather

    I did post details here - http://talk.planethunters.org/#/boards/BPH0000007/discussions/DPH0001f4l

    Perhaps the two threads need to be merged.

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  • JenniferConnors by JenniferConnors

    I often feel like proof or a solution to this mystery may have been over looked or just waiting to be found in this star system. Most speculations lack a significant proof.

    I have studied this star system in a multitude of ways over the years and at every turn I have found nothing that appears to not be natural. As a thought of looking for a solution I recently created a gallery for images of KID 8462852. Nothing can be assumed from it, while the possibility of gaining ideas of what to look for remains. We know we are looking for something that would cause a 15% drop in the light curve.

    I have also taken notice of a background star that is in motion/ or mysteriously becomes brighter and larger than KIC 8462852 at times.
    See the picture where the back ground star at 12:30 suddenly becomes brighter and larger than KID 8462852. Any thoughts on that?

    Gallery KID 8462852

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  • johnfairweather by johnfairweather

    This might be of interest - https://www.reddit.com/r/KIC8462852

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