Closing in on 'Alien Megastructure' clues

When Kepler detects an exoplanet, it does so by sensing the very slight dip in starlight from a given star. The premise is simple: an exoplanet orbits in front of star (known as a “transit”), Kepler detects a slight dimming of starlight and creates a “lightcurve” — basically a graph charting the dip in starlight over time. Much information can be gleaned from the lightcurve, such as the physical size of the transiting exoplanet. But it can also deduce the exoplanet’s shape.
Normally the shape of an exoplanet isn’t particularly surprising because it’s, well, planet-shaped. It’s round.
But say if Kepler detects something that isn’t round.
That's what happened in October when a star, named KIC 8462852 and nicknamed "Tabby's Star", has been found with a highly curious transit signal. In a paper submitted to the journal Monthly Notices of the Royal Astronomical Society, astronomers, including citizen scientists from the Planet Hunters crowdsourcing program, report: “Over the duration of the Kepler mission, KIC 8462852 was observed to undergo irregularly shaped, aperiodic dips in flux down to below the 20 percent level.”
For a mission that deals in transits that usually dim starlight by fractions of a percent, you can see why this signal caused a stir.
Most interestingly, this signal was confirmed to be real, so it wasn't instrumental or analysis error, so astronomers started working on possible explanations. It wasn't long before the “alien" card was pulled and the world's media latched on — was this the first direct evidence of an advanced alien civilization building some kind of “megastructure" around their host star? Could this be the first evidence of a partially built “Dyson Sphere"?
Now, in research from Harvard-Smithsonian Center for Astrophysics, astronomers have studied Tabby's star using the Submillimeter Array and the James Clerk Maxwell Telescope, located atop Mauna Kea in Hawaii, in an effort to possibly track down dust associated with a planetary collision. The warm dust that would be produced by such an event should glow in emissions at submillimeter and millimeter wavelengths.
They found none. So their results appear to favor the exocomet hypothesis for its very strange transit signal.

http://www.seeker.com/likely-exocom...astructure-clues-1803581125.html?sf26667184=1