KIC 8462852, Tabby's Star

• an F3V star in Cygnus .

• Anomalous 22% dimming observed by the Kepler Space Telescope

• nicknamed after Tabetha S. Boyajian, LSU Baton Rouge, the astronomer who pushed for further observation

• NASA: October 4, 2017:Mysterious Dimming of Tabby's Star May Be Caused by Dust

  • From January to December 2016, the researchers observed Tabby's Star in ultraviolet using Swift, and in infrared using the Spitzer Space Telescope.

  • The smoking gun: Researchers found less dimming in the infrared light from the star than in its ultraviolet light. Any object larger than dust particles would dim all wavelengths of light equally when passing in front of Tabby's Star.

• Meng, Huan Y.A.; et al. (3 October 2017). "Extinction and the Dimming of KIC 8462852". The Astrophysical Journal. 847 (2): 131. doi:10.3847/1538-4357/aa899c

• Tabor, Abby , Phys.org (5 October 2017). "The scientific quest to explain Kepler's most enigmatic find"

So, Tabby's star is interesting, and we have more to learn. Will the dust cloud eventually collapse into a planetoid, millions of years from now? Not enough data to model that yet, but we can gather plenty more over the coming centuries.

• Some speculate that Tabby's star is surrounded by a partially constructed "Dyson Sphere"... which Freeman Dyson calls a "shell", a collection of synchronized orbiting objects, and attributed to the 1937 novel Star Maker by Olaf Stapledon.

  • "Sphere" is a misnomer from a sloppy journalist, implying a solid shell, which Dyson did not.
    • Without a source of internal support, no shell made of any material we know about can support itself against the gravity of a star.
    • objects in different orbits all orbit around the same orbital center, so the orbital tracks cross. It is possible to arrange them in a Hill-Clohessy-Wiltshire arrangement to co-rotate elliptically around a common center, but you can't surround an entire star that way.

• If an artificial shell is very very thin (micrometer thickness, grams per square meter), then light pressure can balance gravity; both forces are inverse square at large distances from the central star. There's no place for people to live, and the shell must still radiate the captured energy as heat into space with blackbody radiation. A shell around our Sun at Mars distance would be hotter than 70°C, and interfere with Earth cooling, heating our planet by an additional 90°C (at least), boiling away the oceans and atmosphere.

• A better option for our solar system would be a 60 Kelvin (-210°C) StadyShell at 50 AU from the Sun, constructed from Kuiper belt and Oort cloud ice. Cold objects are much more chemically stable than hot ones, and information processing is 5 times as power efficient.