Star with an “megastructure” in orbit: and yet it’s not a comet

The star KIC 8462852, whose brightness fluctuations were previously explained by a huge cloud of comets in its orbit, again presented astronomers with a surprise . It turned out that its brightness decreases significantly over time - this was established by studying historical images of the sky over the past hundred years. Scientists refute the cometary version, but do not yet know what to offer in return.

In October 2015, a star with catalog number KIC 8462852 broke into the headlines of the mediadue to its unusual properties, and almost the same unusual explanation of these properties. Periodic changes in the brightness of the star attracted the attention of scientists. The star was discovered as part of the Kepler project - a telescope scanned the sky for stars that periodically change brightness. These changes are caused by the transit (passage) of the planets across the disk of the star - in this way Kepler searches for exoplanets.


Data on the fading of the star’s brightness.

However, the KIC 8462852 star had periodic blackouts of 15% and 22% of the brightness, which is too much for a planet passing through its disk. According to the period of brightness drop, we can estimate the diameter of the orbit along which the planet moves around the star. Even if our Jupiter flied around it, it would cause a decrease in brightness of no more than 4%.

In September 2015, scientists who discovered this star proposed the following explanation of its behavior. If in the star’s orbit there is a sufficiently large cloud of comets, then dust from them may well cover the star so that its brightness drops significantly.

And in October 2015, astronomer Jason Wright suggested that some megastructure that aliens can build around a star can cause such an effect - for example, such a thing as the Dyson sphere known to science enthusiasts.

In the 1960s, physicist Freeman Dyson suggested that civilizations of old stars would be forced to rebuild their system planets so as to surround their fading star with planet matter. Such a design will be able to catch and master all the energy emitted by it.


Dyson Sphere Design

According to Wright, such a structure, which is under construction, could obscure the star. Such a bold assumption led to the popularization of this news. But, unfortunately, attempts to find a developed civilization in this star have failed . Listening on the radio waves did not reveal any suspicious signals, the infrared telescope also showed nothing interesting.

But astronomer Bradley Schaefer decided not to stop there, and to study scans of historical images of this area of ​​the sky, taken from 1890 to 1989. It turned out that during this time, the brightness of the star decreased by 20%.

To eliminate the possibility of errors, Schaeffer personally went to Harvard to study the original pictures. According to Wright, “since no one is using photographic plates, studying them is a lost art. And Schaefer is an expert in this matter. ”

According to Schaefer, the comet hypothesis is no longer suitable for explaining the observed effects. According to his calculations, for such a darkening, at least 648,000 comets, each with a diameter of 200 km or more, should have flown before the star, which is absolutely unbelievable. Schaefer says that the comet hypothesis was the least bad of all the proposed ones - astronomers admitted that all the ideas proposed were unsuccessful in their own way. Now, for the strange behavior of the star, new explanations are required.

Nevertheless, the idea of ​​an alien structure that excites the minds of lonely earthlings is hardly suitable here either. Firstly, according to Schaefer, it is unlikely that even an advanced civilization could build a structure that covers the fifth of the star in just a hundred years. Secondly, such a structure, which absorbs star radiation, inevitably had to emit in the infrared range - which observations do not confirm.