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KIC 8462852: Fading in the Kepler Data

Those of you who have been following the controversy over the dimming of KIC 8462852 (Tabby’s Star) may remember an interesting note at the end of Bradley Schaefer’s last post on Centauri Dreams. Schaefer (Louisiana State University) had gone through his reasoning for finding a long-term dimming of the star in the DASCH (Digital Access to a Sky Century@Harvard) database. His third point about the star had to do with the work of Ben Montet (Caltech) and Joshua Simon (Carnegie Observatories).

Montet and Simon’s work relied on an interesting premise. Tabby’s Star had been discovered because it was in the Kepler field, and thus we had high-quality data on its behavior, the unusual light curves that the Planet Hunters team brought to the attention of Tabetha Boyajian. As the researchers note in a new paper, Kepler found ten significant dips in the light curve over the timespan of the Kepler mission, dips that were not only aperiodic but irregular in shape, and that varied enormously, from fractions of one percent up to 20% of the total flux of KIC 8462852.


Image: Montage of flux time series for KIC 8462852 showing different portions of the 4-year Kepler observations with different vertical scalings. Panel ‘(c)’ is a blowup of the dip near day 793, (D800). The remaining three panels, ‘(d)’, ‘(e)’, and ‘(f)’, explore the dips which occur during the 90-day interval from day 1490 to day 1580 (D1500). Credit: Boyajian et al., 2015.

Schaefer noted in his Centauri Dreams post (see Further Thoughts on the Dimming of KIC 8462852) that if Tabby’s Star were actually fading at a rate of 0.164 mag/cen, then it should have undergone fading during the period it was under observation by Kepler (in fact, it should have faded by 0.0073 mag over the Kepler lifetime on the main Cygnus field). Montet and Simon have now presented us with their analysis in a paper just up on the arXiv server.

A fading of the kind Schaefer described would be well above the photometric precision of the Kepler instrument. Montet and Simon realized they could search for long-term trends by using the full-frame images (FFI) collected during the Kepler mission. Eight of these were recorded at the beginning of the mission, with another FFI recorded each month throughout the mission. Given that the mission lasted four years, a star dimming at the rate Schaefer suggests should decrease in brightness by 0.6% over the Kepler baseline. And as the authors point out, using FFI data avoids the removal of the dimming trend by the data processing pipeline.

The results: The study, which worked with KIC 8462852 and seven nearby comparison stars, found that in the first three years of the Kepler mission, Tabby’s Star dimmed at a rate of 0.341%±0.041% per year. Over the next six months, it decreased in brightness by 2.5%, and then stayed at that level during the duration of the primary Kepler mission. The paper continues:

We then compare this result to a similar analysis of other stars of similar brightness on the same detector, as well as stars with similar stellar properties, as listed in the KIC, in the Kepler field. We find that 0.5% of stars on the same detector and 0.7% of stars with similar stellar properties exhibit a long-term trend consistent with that observed for KIC 8462852 during the first three years of the Kepler mission. However, in no cases do we observe a flux decrement as extreme as the 2.5% dip observed in Quarters 12-14 of the mission. The total brightness change of KIC 8462852 is also larger than that of any other star we have identified in the Kepler images.

Screenshot from 2016-08-05 11:11:46

Image: Photometry of KIC 8462852 as measured from the FFI data. The four colors and shapes (green squares, black circles, red diamonds, and blue triangles) represent measurements from the four separate channels the starlight reaches as the telescope rolls. The four subpanels show flux from each particular detector individually. The main figure combines all observations together; we apply three linear offsets to the data from different channels to minimize the scatter to a linear fit to the first 1100 days of data. In all four channels, the photometry is consistent with a linear decrease in flux for the first three years of the mission, followed by a rapid decrease in flux of ≈ 2.5% over the next six months. The light gray curve represents one possible Kepler long cadence light curve consistent with the FFI photometry created by fitting a spline to the FFI photometry as described in Section 4. The large dips observed by Boyajian et al. (2016) are visible but narrow relative to the cadence of FFI observations. The long cadence data behind this figure are available online. Credit: Montet & Simon.

M. A. Thompson (University of Hertfordshire) and colleagues published a recent study in Monthly Notices of the Royal Astronomical Society reporting their findings using millimetre and sub-millimetre photometry. The paper finds that a dust cloud orbiting Tabby’s Star would have to be no larger than 7.7 Earth masses of material within a radius of 200 AU, adding “Such low limits for the inner system make the catastrophic planetary disruption hypothesis unlikely.”

Montet and Simon don’t necessarily agree, but in any case there are other problems. The authors think the light curve is “…consistent with the transit of a cloud of optically thick material orbiting the star,” and that such a cloud could be small enough to meet Thompson and team’s requirements. The breakup of a small body or a recent collision producing a large dust cloud could also produce a cometary family that transited the host star as a single group. But we’re still not out of the woods:

To explain the transit ingress timescale, the cloud would need to be at impossibly large distances from the star or be slowly increasing in surface density. The flat bottom of the transit would then suggest a rapid transition into a region of uniform density in the cloud, which then continues to transit the star for at least the next year of the Kepler mission. Moreover, such a model does not naturally account for the long-term dimming in the light curve observed in both DASCH and the Kepler FFI data, suggesting that this idea is, at best, incomplete.

A deeply mysterious star, our KIC 846285. Montet and Simon call for alternative hypotheses and new data to help us explain existing observations, and we can be glad to have Tabetha Boyajian’s team on the case thanks to the success of the recent Kickstarter campaign. Observations are already in progress at the Las Cumbres Observatory Global Telescope Network, and the Kickstarter funds will take us deep into 2017. For more on the Las Cumbres work, see Corey Powell’s recent interview with Boyajian for Discover Magazine, from which this:

From our new observations, we’ll be able to tell a lot about the material that’s passing in front of the star: if it’s some kind of dusty thing, some kind of solid thing. [Boyajian’s working hypothesis is that the dimming is caused by a huge swarm of comets, set loose perhaps by some cataclysmic event around the star.] What’s also important is that we will also get a baseline of spectral observations so we can look at if there’s any radial velocity shift or if there’s any variable emission of the lines, things we’d expect comets to have.

The paper is Montet and Simon, “KIC 8462852 Faded Throughout the Kepler Mission,” submitted to the AAS Journals and available as a preprint. The Thompson paper on circumstellar dust in this system is “Constraints on the circumstellar dust around KIC 8462852,” published online by Monthly Notices of the Royal Astronomical Society 25 February 2016.


Comments on this entry are closed.

  • ljk October 4, 2016, 12:17


    Photometric and astrometric vagaries of the enigma star KIC 8462852

    Valeri V Makarov, Alexey Goldin

    (Submitted on 13 Sep 2016 (v1), last revised 26 Sep 2016 (this version, v2))

    We apply a PCA-based pre-whitening method to the entire collection of main Kepler mission long-cadence data for KIC 8462852 spanning four years. This technique removes the correlated variations of instrumental origin in both the detected light curves and astrometry, resolving intrinsic changes in flux and image position of less than 100 ppm and 1 mas, respectively. Beside the major dips in the light curve during mission quarters 8 and 16, when the flux dropped by up to 20%, we confirm multiple smaller dips across the time span of observation with amplitudes ranging from 0.1% to 7%. A variation of flux with a period of 0.88 d and a half-amplitude of approximately 90 ppm is confirmed in the PCA-cleaned data. We find that the phase of the wave is steady over the entire 15-month interval. We confidently detect a weak variability-induced motion (VIM) effect in the cleaned astrometric trajectories, when the moment-based centroids shift synchronously with the flux dips by up to 0.0008 pixels on the detector. The inconsistent magnitude and direction of VIM effects within the same quarter point at more than one source of photometric variability in the blended image. The 0.88 d periodicity comes from a different source, not from the target star KIC 8462852.

    We discuss a possible interpretation of the bizarre properties of the source as a swarm of interstellar junk (comets and planetoids) crossing the line of sight to the star and its optical companions at approximately 7 mas per year.

    Comments: submitted in ApJ. The most significant change with respect to previous version is a new clue discussed in Section 6 about the foreground junk hypothesis where we discuss the proximity of the target star to a filamentary H-alpha emission nebula DWB 123 possibly associated with the peculiar Simeiz 57 (Propeller Nebula) cloud, and a new Fig. 12 showing a DSS-red image of the extended area

    Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

    Cite as: arXiv:1609.04032 [astro-ph.SR]
    (or arXiv:1609.04032v2 [astro-ph.SR] for this version)

    Submission history

    From: Valeri Makarov [view email]

    [v1] Tue, 13 Sep 2016 20:15:05 GMT (1363kb)
    [v2] Mon, 26 Sep 2016 07:58:26 GMT (2460kb)


  • ljk October 4, 2016, 12:23


    Sonneberg Sky Patrol Archive – Photometric Analysis

    Milan Spasovic, Christian Dersch, Christian Lange, Dragan Jovanovic, Andreas Schrimpf

    (Submitted on 2 Oct 2016)

    The Sonneberg Sky Patrol archive so far has not yet been analyzed systematically. In this paper we present first steps towards an automated photometric analysis aiming at the search for variable stars and transient phenomena like novae. Early works on the sky patrol plates showed that photometric accuracy can be enhanced with fitting algorithms. The procedure used was a manually supported click-and-fit-routine, not suitable for automatic analysis of vast amount of photographic plates.

    We will present our progress on deconvolution of overlapping sources on the plates and compare photometric analysis using different methods. Our goal is to get light curves of sufficient quality from sky patrol plates, which can be classified with machine learning algorithms. The development of an automated scheme for finding transient events is in progress and the first results are very promising.

    Comments: 4 pages, 4 figures, Proceedings Astroplate 2016, Prague, in print

    Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)

    Cite as: arXiv:1610.00265 [astro-ph.IM]
    (or arXiv:1610.00265v1 [astro-ph.IM] for this version)

    Submission history

    From: Andreas Schrimpf [view email]

    [v1] Sun, 2 Oct 2016 11:55:31 GMT (705kb,D)


  • Kevin Longbrake October 6, 2016, 7:04

    This star is producing large amounts of iron through fusion. This is causing the reaction to become unstable thereby causing the fluctuations in brightness. The star will eventually go supernova.

    • ljk October 6, 2016, 11:44

      Where are you getting this information from? And why has this not been mentioned before, at least to my (incomplete) knowledge about the star? Thank you.

  • Kevin Longbrake October 6, 2016, 13:15

    I’m not a scientist. I am just postulating reasonable explanations for such variance in start brightness. This is the only reasonable explanation for such changes and brightness of a star, as other theories have been ruled out, and I seriously doubt it is an alien megastructure. Course I could be wrong, but it’s in my mind a more reasonable explanation than what I’ve heard so far. One individual said a type F star is in capable of having enough mass to go supernova, nor enough mass to generate iron. It could however be creating carbon. I postulate that it is this carbon that is interfering with the nuclear fusion of the star thereby resulting in an in even reaction reducing and increasing the stars brightness. This is just a theory I came up with in my head, I hope the real scientist out there figure it out.

    • EricSECT October 7, 2016, 5:58

      This is the issue I have with Tabby’s Star and any “Therefore, it MUST be ETI!” default: In reality, there are very large uncertainties in any at all precise determination of the age of any individual star (besides Sol). I’m not talking groups of stars born together. These uncertainties can approach 30%. An “F” type star such as Tabby’s is expected to live only a handful of billions of years, much less than Sol at about a 10 billion year long main sequence lifetime. Let’s just consider that Tabby’s MS lifetime will total 3 billion years. Now, if our calculated value for age has uncertainties of 30%-ish (…and if our theoretical models and computer models need just a little tweaking…. that would add even more uncertainties….) instead of Tabby’s being middle aged like everyone is assuming, it may be at end-of-life and just about to exit the MS. So it’s behavior can be explained as simply instability as the hydrogen fusion reaction sputters and falters. Perhaps this instability for this type star only last 1000 years, that is why we have yet to see any other stars acting like this. As simple as that. Of course, I would love to be proven wrong!

  • ljk October 21, 2016, 10:50

    The High Rate of the Boyajian’s Star Anomaly as a Phenomenon

    Brian C. Lacki

    (Submitted on 11 Oct 2016)

    Boyajian’s Star (KIC 8462852) undergoes mysterious, irregular eclipses that aren’t yet explained. It also appears to have dimmed over a time of several years, possibly decades. I show that Kepler’s detection of a phenomenon with a duration of t_anom is only expected if it occurs at a mean rate of >~ 30 Gyr^(-1) (t_anom / 100 yr)^(-1) for each Kepler target and K2 star. If true, the phenomenon occurs hundreds of times during the lifespan of its host stars.

    Obscuration by the interstellar medium remains a plausible explanation, since it doesn’t actually affect the host star. An intervening cloud is consistent with the lack of an observed submillimeter excess but would be abnormally dilute.

    Comments: 8 pages (aastex6), 1 table, no figures

    Subjects: Astrophysics of Galaxies (astro-ph.GA); Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

    Cite as: arXiv:1610.03219 [astro-ph.GA]
    (or arXiv:1610.03219v1 [astro-ph.GA] for this version)

    Submission history

    From: Brian Lacki [view email]

    [v1] Tue, 11 Oct 2016 07:24:00 GMT (52kb)


    • EricSECT October 22, 2016, 10:15

      This Lacki paper is an excellent source for all the background, papers included, surrounding Tabby’s Star.

      The paper does NOT seem to reach a specific conclusion though.

  • ljk October 21, 2016, 10:52


    Families of Plausible Solutions to the Puzzle of Boyajian’s Star

    Jason T. Wright, Steinn Sigurdsson

    (Submitted on 12 Sep 2016 (v1), last revised 23 Sep 2016 (this version, v2))

    Good explanations for the unusual light curve of Boyajian’s Star have been hard to find. Recent results by Montet & Simon lend strength and plausibility to the conclusion of Schaefer that in addition to short-term dimmings, the star also experiences large, secular decreases in brightness on decadal timescales. This, combined with a lack of long-wavelength excess in the star’s spectral energy distribution, strongly constrains scenarios involving circumstellar material, including hypotheses invoking a spherical cloud of artifacts.

    We show that the timings of the deepest dimmings appear consistent with being randomly distributed, and that the star’s reddening and narrow sodium absorption is consistent with the total, long-term dimming observed. Following Montet & Simon’s encouragement to generate alternative hypotheses, we attempt to circumscribe the space of possible explanations with a range of plausibilities, including: a cloud in the outer solar system, structure in the ISM, natural and artificial material orbiting Boyajian’s Star, an intervening object with a large disk, and variations in Boyajian’s Star itself. We find the ISM and intervening disk models more plausible than the other natural models.

    Comments: 15 pages, accepted to ApJL, 3 color figures. See also this http URL for a popular summary of the article v2: Typos fixed

    Subjects: Astrophysics of Galaxies (astro-ph.GA)

    DOI: 10.3847/2041-8205/829/1/L3

    Cite as: arXiv:1609.03505 [astro-ph.GA]
    (or arXiv:1609.03505v2 [astro-ph.GA] for this version)

    Submission history

    From: Jason Wright [view email]

    [v1] Mon, 12 Sep 2016 17:56:03 GMT (191kb,D)
    [v2] Fri, 23 Sep 2016 14:21:46 GMT (191kb,D)


    • EricSECT October 22, 2016, 10:50

      This is an excellent summary of dimming hypothesis. The various hypothesis are weighed and ranked.

      The conclusion is that ISM/BOK globule seems the most plausible, that’s how I read it.

      I was disappointed that the (calculated value for) age of Tabby’s Star was not considered. This CV has large, inherent errors (+/- 30%). This F3 star has an expected MS lifetime of about 3 billion years. It may NOT be “middle aged”. We do not know for certain WHERE this star is on the main sequence.

      I still think that the least contrived explanation for Tabby’s weird behavior is a simple one: It is just about to exit the MS. The hydrogen fusion reaction is sputtering out, or has totally extinguished. Instability explains all the data we have: The lack of excess IR, Schaeffer’s Harvard Plates long term dimming, Montet’s 4 year Kepler data dimming and and Kepler’s random dips through out the 4 years of observation.

      Or am I all wet?

      • ljk October 26, 2016, 9:38

        No I think you are on to something. I remember trying to find data on the age of Tabby’s Star and being disappointed at finding so little – and then wondering why this wasn’t taken into account more when coming up with all the reasons for what we are seeing around that star.

        • EricSECT October 26, 2016, 13:46

          Along with the age of Tabby’s star, itself a calculated value, there is also the issue of the diameter of Tabby’s star, which is not a calculated value but rather an assumed value, things we can measure…. Tabby’s diameter being that of 1.46 times that of Sol due to it’s color, metallicity and surface temperature, an ASSUMED middle aged “F” star.

          Look at the d1540 triple dip signature. It looks like a ringed planet, embedded in a cloud that surrounds and obscures this planet by 1% and last for 11 days. The the center dip “planet” dims another 2%. The 3 dips each take about 1/2 day to transit the disc of the star. But this triple signature does NOT repeat for the entirety of the Kepler data, it is a one time event. So ….if assumed that this object is in orbit, it’s periodicity must >1500 days-ish. The only way that works if if Tabby’s Star diameter is less than expected, at about 2/3rds that of Sol. And if Tabby’s diameter is that small, a planet transit of 2% dimming is not outrageous.

          There may be something way wrong with this star! End of life. Collapsing. Hydrogen fusion reactions have stopped. About to exit the main sequence, about to become a red giant(in what, ten thousand years?). An unstable region, sputtering and flickering out.

  • ljk October 26, 2016, 9:40

    Breakthrough Listen to search for intelligent life around weird star

    By Robert Sanders, Media relations | October 25, 2016

    Tabby’s star has provoked so much excitement over the past year, with speculation that it hosts a highly advanced civilization capable of building orbiting megastructures to capture the star’s energy, that UC Berkeley’s Breakthrough Listen project is devoting hours of time on the Green Bank radio telescope to see if it can detect any signals from intelligent extraterrestrials.


    To quote:

    While Siemion and his colleagues are skeptical that the star’s unique behavior is a sign of an advanced civilization, they can’t not take a look. They’ve teamed up with UC Berkeley visiting astronomer Jason Wright and Tabetha Boyajian, the assistant professor of physics and astronomy at Louisiana State University for whom the star is named, to observe the star with state-of-the-art instruments the Breakthrough Listen team recently mounted on the 100-meter telescope. Wright is at the Center for Exoplanets and Habitable Worlds at Pennsylvania State University.

    The observations are scheduled for eight hours per night for three nights over the next two months, starting Wednesday evening, Oct. 26. Siemion, Wright and Boyajian are traveling to the Green Bank Observatory in rural West Virginia to start the observations, and expect to gather around 1 petabyte of data over hundreds of millions of individual radio channels.


    Speculation eventually arose that the dimming was caused by a Dyson structure: a massive orbiting array of solar collectors that physicist Freeman Dyson once proposed would be a natural thing for a civilization to build as it needed more and more energy to power itself. Theoretically, such a structure could completely surround the star – what he termed a Dyson sphere – and capture nearly all the star’s energy.

    How likely is that?

    “I don’t think it’s very likely – a one in a billion chance or something like that – but nevertheless, we’re going to check it out,” said Dan Werthimer, chief scientist at Berkeley SETI. “But I think that ET, if it’s ever discovered, it might be something like that. It’ll be some bizarre thing that somebody finds by accident … that nobody expected, and then we look more carefully and we say, ‘Hey, that’s a civilization.’”

  • ljk October 26, 2016, 9:56

    From the UC Berkeley article above:

    Wright, Boyajian and Siemion will engage in a live video chat from the Green Bank Telescope at 4 p.m. EDT (1 p.m. PDT) Wednesday, Oct. 26, about their Tabby’s star observations.

    The online chat will be broadcast here:


    • ljk October 27, 2016, 9:39

      The live chat about Tabby’s Star is archived here:


      • Trindade November 2, 2016, 10:28

        1 – How the temperature, size, color and age were determined?
        2 – If alien structure is the less plausible explanation, what are they doing in SETI?

        • EricSECT November 7, 2016, 8:38

          I agree, Trindale, that we may be under a wrong presumption re: the star’s age. A star’s color, luminosity and spectrum (metallicity, doppler velocity and/or smearing) are the observable traits.

          Age is a calculated value based on theoretical models that input the observable qualities into a computer model, which spits out an age… with very large uncertainties!!!!… that are being glossed over or ignored.

  • ljk November 28, 2016, 18:00

    Strange star has E.T. seekers looking closely for signs of life

    By David Perlman

    Updated 7:52 pm, Thursday, November 24, 2016

    Berkeley astronomers on a new hunt for E.T. are aiming one of the world’s most powerful radio telescopes at the most bizarre star ever detected.

    They have tuned the big telescope at the Green Bank Observatory in West Virginia to listen for signals from an object in space called Tabby’s Star, whose implausible behavior is puzzling astronomers all over the world.

    That star might conceivably be a sign that some civilization far more advanced than our own is, or has been, building some kind of giant structure far off in the Milky Way, they say.

    Full article here:


  • Tom Mazanec December 5, 2016, 18:41
  • ljk December 16, 2016, 17:00

    Astronomers observe mysterious dimming of a young nearby star

    December 16, 2016

    by Tomasz Nowakowski

    (Phys.org)—Astronomers have spotted transient, transit-like dimming events of a young star named RIK-210 located some 472 light years away in the Upper Scorpius OB association. However, what puzzles the scientists is the mystery behind this dimming as it can not be caused by an eclipsing stellar or brown dwarf companion. They describe their search for plausible explanations in a paper published Dec. 12 on the arXiv pre-print server.


    RIK-210 is around five to 10 million years old, about half as massive as the sun and has a radius of approximately 1.24 solar radii. The star has been recently observed by NASA’s prolonged Kepler mission, known as K2, during its Campaign 2, lasting from Aug. 22 to Nov. 11, 2014. A team of researchers led by Trevor David of the California Institute of Technology (Caltech) has analyzed the data provided by K2.

    “We find transient, transit-like dimming events within the K2 time series photometry of the young star RIK-210 in the Upper Scorpius OB association. These dimming events are variable in depth, duration, and morphology,” the scientists wrote in the paper.

    Full article here:


    To quote:

    The team found that these dimming events occur approximately every 5.67 days, in phase with the stellar rotation, noting that they are deep (sometimes greater than 15 percent) and short in duration relative to the rotational period. Moreover, the morphology of the dimmings is variable throughout the whole observational campaign, while the starspot modulation pattern remains stable over this period of time.

    While such variable dimmings have been documented around mature stars and stellar remnants, it has not been previously observed around a young star lacking a protoplanetary disk, as in the case of RIK-210.

    In the search for possible explanations of the observed transient, transit-like dimming events, the researchers at first excluded the possibility that they can be caused by an eclipsing stellar or brown dwarf companion. This hypothesis was ruled out as it is inconsistent with radial velocity measurements as well as with archival and follow-up photometry data.

  • ljk December 21, 2016, 16:38

    Avalanche statistics suggest Tabby’s star is near a continuous phase transition

    December 20, 2016

    by Siv Schwink

    In its search for extrasolar planets, the Kepler space telescope looks for stars whose light flux periodically dims, signaling the passing of an orbiting planet in front of the star. But the timing and duration of diminished light flux episodes Kepler detected coming from KIC 846852, known as Tabby’s star, are a mystery. These dimming events vary in magnitude and don’t occur at regular intervals, making an orbiting planet an unlikely explanation. The source of these unusual dimming events is the subject of intense speculation.

    Suggestions from astronomers, astrophysicists, and amateur stargazers have ranged from asteroid belts to alien activity.

    Now a team of scientists at the University of Illinois at Urbana-Champaign—physics graduate student Mohammed Sheikh, working with Professors Karin Dahmen and Richard Weaver—proffer an entirely novel solution to the Tabby’s star puzzle. They suggest the luminosity variations may be intrinsic to the star itself. Tabby’s star is in most regards a standard F-class star, located in the constellation Cygnus, approximately 1,276 light years from Earth. Its unusual light curve—the graph of its light intensity as a function of time—shows intense dimming events of up to 20 percent, punctuated with smaller irregular dimming events.

    Full article here:


    • EricSECT December 21, 2016, 19:16

      The fusion reaction slows down and stops. The star contracts, the core heats up, fusion restarts, etc. Eventually, the star will reach a point, run out of fuel, and contract and heat up and STILL give of heat and light, not due to nuclear fusion but due to gravity contraction. This instability should last hundreds, thousands of years. Eventually, it will get to the point where the core is so HOT, the star has contracted so much, that starts to fuse Helium and thus, Red giant.

      We all need to appreciate that compared to our human perception, the life time and life stages of a star are VAST, beyond imagining. Transitions take a long time.

      This star is at the cusp of it’s hydrogen fusion reactions sputtering out as the fuel is exhausted, and has entered the unstable region, about to exit the MS and go Red giant. This star is not middle aged, it is at normal end-of-life.

      Predictions: Future major dimming events will continue to be random and some, deep. The overall luminosity of the star will continue to drop off. NO infrared excess will be detected, even by JWST. Eventually, we will observe other stars going through this death rattle, just like Tabby’s is.

  • ljk December 23, 2016, 10:10

    The latest from Jason Wright’s AstroWright blog:


    Thoughts on Neslušan and Budaj

    A lot of folks want to know my opinion about the two new Tabby’s Star papers out this week:

    Mohammed A. Sheikh, Richard L. Weaver, and Karin A. Dahmen

    Phys. Rev. Lett. 117, 261101

    With commentary by Steinn Sigurdsson here:


    On this one, my opinion closely matches Steinn’s (because I asked him to explain it to me!). From what I understand of the paper, certain statistics of the dips follow a power law, and so-called “avalanche” models of certain phenomena associated with phase transitions follow a similar power law. The authors suggest that this means that the processes causing the dips are internal to the star, and represent some sort of transition it is undergoing, like a global magnetic field flip.

    That’s interesting, but I don’t know what it really means. It may provide a way for physical models to try to reproduce the data, by asking if the dips they predict follow the same power law.

    Neslušan & Budaj A&A accepted:


    Mysterious eclipses in the light-curve of KIC8462852: a possible explanation
    L. Neslusan, J. Budaj

    (Submitted on 19 Dec 2016 (v1), last revised 22 Dec 2016 (this version, v2))

    Apart from thousands of `regular’ exoplanet candidates, Kepler satellite has discovered a few stars exhibiting peculiar eclipse-like events. They are most probably caused by disintegrating bodies transiting in front of the star. However, the nature of the bodies and obscuration events, such as those observed in KIC8462852, remain mysterious. A swarm of comets or artificial alien mega-structures have been proposed as an explanation for the latter object.

    We explore the possibility that such eclipses are caused by the dust clouds associated with massive parent bodies orbiting the host star.

    We assumed a massive object and a simple model of the dust cloud surrounding the object. Then, we used the numerical integration to simulate the evolution of the cloud, its parent body, and resulting light-curves as they orbit and transit the star.

    We found that it is possible to reproduce the basic features in the light-curve of KIC8462852 with only four objects enshrouded in dust clouds. The fact that they are all on similar orbits and that such models require only a handful of free parameters provides additional support for this hypothesis.

    This model provides an alternative to the comet scenario. With such physical models at hand, at present, there is no need to invoke alien mega-structures for an explanation of these light-curves.

    Comments: Accepted to A&A. Identical to v1 but with language correction

    Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

    Cite as: arXiv:1612.06121 [astro-ph.EP]
    (or arXiv:1612.06121v2 [astro-ph.EP] for this version)

    Submission history

    From: Jan Budaj [view email]

    [v1] Mon, 19 Dec 2016 11:08:00 GMT (788kb)
    [v2] Thu, 22 Dec 2016 14:04:35 GMT (789kb)


  • ljk January 25, 2017, 19:29

    So did Tabby’s Star consume a planet instead of having a shell of advanced ETI technology around it? See here:


    Here is what Jason Wright had to say about this idea: