More strange behavior from Tabby’s Star

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Astronomers reviewing past data of KIC 8462852, known as Tabby’s Star to the public, have discovered that not only has it been dimming in a variety of inexplicable ways, it also has brightened twice in a manner that eliminates all past theories for its behavior, including alien megastructures.

The latest findings from Carnegie’s Josh Simon and Benjamin Shappee and collaborators take a longer look at the star, going back to 2006—before its strange behavior was detected by Kepler. Astronomers had thought that the star was only getting fainter with time, but the new study shows that it also brightened significantly in 2007 and 2014. These unexpected episodes complicate or rule out nearly all the proposed ideas to explain the star’s observed strangeness.

Up until now, all the changes to the star had involved dimming, though in ways that did not fit any present theory of stellar evolution. Thus, astronomers theorized that the dimming was caused by something moving in front of the star, from comets to dust to alien structures. This new data of two significant brightening events makes all those theories invalid.

Update: More news about Tabby’s Star: Using two space telescopes as well as amateur telescopes on the ground scientists have determined that the dimming must come from an uneven dust cloud.



  • Brendan

    The Aliens were exploding planets to gain access for the ring world. It really is the only answer!

  • LocalFluff

    “Dust” covering 20% of the starlight suddenly and without any periodicity, that’s nonsense! It might be the least bad fit of the current Lego pieces, but it still doesn’t fit. It might be an odd variable star, though there are none known in its spectral class and stellar physicists don’t seem to like it.

  • LocalFluff: I agree. This star is doing things that no theory yet explains.

  • Matt in AZ

    As this star’s fluctuations get stranger with each closer look, I’m increasingly glad it’s over a thousand light years away.

  • The star is some distance away. Could an interstellar structure of some sort (cloud, debris field, etc.) in the intervening space be a contributor?

  • Blair Ivey: The nature of the dimming appears to preclude blockage by a solid object.

  • LocalFluff

    “They also did not confront the mystery of the major 20-percent dips in brightness that Kepler observed”

    And thus it is not at all so determined. I actually read it as meaning that it is less likely for a dust cloud to explain it, since only fairly large dust particles can stay in orbit.

    My guess is that this is happening on the surface of the star. The dips don’t look like transits of massive objects and the spectra, it seems, don’t show the redness that local dust would cause, and it is brightening as well as dimming. There are a few funny stars out there, irregular variables. Stellar physicists don’t seem to like that idea at all, though, because there are no known variable stars at the temperature of an F-star like Boyajian’s.

    But odd things might have happened to a multi-billion years old star. There are the Thorne–Żytkow objects (yes, discovered and named by Kip “the wave” Thorne), red giants with a neutron star orbiting inside of their photospheres. This Boyajian’s star might have collided with something and is now digesting it with interruptions of its fusion process and its energy transfer to the surface.

    @Blair Ivey
    “The star is some distance away. Could an interstellar structure of some sort (cloud, debris field, etc.) in the intervening space be a contributor?”

    If it’s dust, it has to be large grains or far from the star. Otherwise the reddening of the light would reveal it. But it seems very unlikely that an interstellar cloud is dimming one and only one single star, for years, out of the 150 000 stars Kepler watched at the same time. And the dimmings aren’t shaped like transits. And it seems to be brightening too. But light echoes, light reflected by interstellar dust clouds, do play tricks with astronomers, like making some supernovae look like they are expanding faster than the speed of light. And allows astronomers to watch supernovae from the far side! It can also brighten light. But to form such a unique cloud, well that needs some explaining too.

  • Ryan Lawson

    Since the dimming method is apparently problematic for detecting planets there, has there been any attempt to use the old stellar wobble method?

    One of the articles cited says a dust cloud on a 700 day orbit could cause the slow dimming being observed, but that would mean something recently generated it or it is being systematically replenished. This could potentially be evidence not of an alien megastructure, but alien terraforming or industry like pulverizing comets at a sun-side Lagrange point to provide shade to a slightly hot planet.

    Maybe this system has been disturbed by a rogue planet that stirred up an awful lot of cometary material and disrupted planetary orbits, sending something big into the star.

    I love a good space mystery!

  • LocalFluff

    @Ryan Lawson
    I’ve read somewhere that redshift wobbling has been measured, of course, with zero result. No massive body is orbiting that star. That would’ve been a nice clue otherwise.

    In the Solar system, 99.8% of the mass is in the Sun. Most of the rest is in Jupiter. Actually, every planet is more massive than all of the smaller planets together (among the 9 largest planets). The mass of all asteroids, comets and dust in the Solar system is really tiny compared with the huge size of the Solar disk. Tabby’s star has dimmed by up to 22% momentarily. I think that’s very difficult to arrange with dust. And observations have put restrictions on dust so that it must be fairly large grains, and very clumsy instead of a ring since the star is at full brightness most of the time. When Phobos will be crushed by Mars’ tidal forces it will form a ring within weeks.

    Dust and comets is still the idea I hear of most, and I’m not an astronomer, but anything transiting it seems unlikely to me. I bet it’s a weird variable star. Maybe dark matter concentration is messing with the star’s fusion process by displacing its center of gravity? Something freaky like that.

    This messy thread at NSF seems to be quick with any news (but no good explanations):

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