The Kepler Space Telescope has by far been the most effective exoplanet hunter with over 1000 confirmed discoveries and several thousand more potential discoveries waiting to be confirmed. These undiscovered objects get placed on the Kepler Object of Interest list. A few years ago, an object orbiting a star, KIC 8462852, was located about 1500 light years from Earth. Recently, the object was revisited and an interesting discovery was made.
Kepler works by detecting tiny dips in light from distant stars as a planet passes between us, on Earth, and the star. This is known as the transiting method of exoplanet discovery. When a plant transits across its parent star, a predictable light curve is observed and can be seen below. This is not what was seen around KIC 8462852. Normally a transiting planet would cause a slight dip of less than 1% of the normal brightness of a star but the light curve of KIC 8462852 showed dips of up to 20%. These dips also occurred in an unpredictable manner. Seen below are a normal light curve and the light curve of KIC 8462852.
As you can see, there is a big difference in the light curves of a normal transiting planet and the light curve from the star KIC 8462852, but what is causing this?
Several ideas have been put forth as to what might be causing the strange curve including a shattered comet, large dust clouds formed from impacts, an error with the telescope, or the most exciting possibility, an alien mega structure.
The team who did the study easily ruled out the possibility of an error in the telescope.
The possibility of circumstellar dust being the culprit seems unlikely. A possible source of the dust could be either from early solar system formation or impacts of large bodies. Neither of these possibilities are likely though as KIC 8462852 is not a young star and most of the dust that was present would have already formed into planets, comets and asteroids. If the dust came from an impact of two planetesimals (small bodies that can be up to a few hundred kilometres across) we would expect to see infrared radiation from the dust but this wasn’t observed. In addition to this, planetary collisions would produce massive amounts of dust, levels of which wasn’t observed.
The idea of a shattered comet is the most likely cause of the strange light curves. It would produce enough dust to block starlight but not as much as colliding rocks.
The last idea of an alien mega structure is perhaps, more than a bit farfetched nevertheless is remains a possibility. The fact that one of the astronomers who conducted the study speculated about the idea of aliens caused a lot of excitement on the Internet.
One possible structure is the ‘Dyson Sphere,’ a hypothetical structure that surrounds a star and absorbs its solar energy. The strange light curves could be due to this giant object slowly orbiting its star supplying an advanced alien race with all of the energy it’d ever need.
Tabetha Boyajian, head of the study, Andrew Siemion, the director of the SETI institute who listen in for radio signals from distant worlds and Jason Wright, of Penn State University have submitted a proposal to point a giant radio telescope at the star to search for non-natural radio signals that may be emitted by a technologically advanced civilization.
The team hopes to begin the study in January.