The star dubbed KIC 8462852, slightly bigger than the Sun, located more than 1400 light years away from us in the constellation Cygnus, drew a lot of attention last October, when astronomers analyzed the light it emits and found unusual dimming pattern — 20% and more — an odd phenomenon that could be caused by alien megastructures in orbit there.
Several natural theories were proposed by scientists to explain KIC 8462852’s light, but none of them was entirely satisfactory. The most likely hypothesis point to the existence of family of comets — a dense, irregular debris that, at one point, blocked 22% of the star’s light. Another explanation, which is unlikely but could not completely rule out, involved a technologically sophisticated civilization which has built megastructures, commonly referred to as a Dyson sphere.
Given this possibility, the scientists at the Search for Extraterrestrial Intelligence (SETI) Institute in Mountain View, California (a foundation dedicated to the search for intelligent life in space) did the right thing: they aimed their Allen Telescope Array — consisting of 42 antennas, each nearly 20 feet wide — on KIC 8462852 for any extraterrestrial activity.
Did you know? KIC 8462852 is also nicknamed Tabby’s star (literally, its mean ‘the Tiger Star’ but it’s mostly a main reference after lead author Tabetha S. Boyajian).
For more than two weeks, SETI has been ‘listening’ on star with the Allen Telescope Array in to two specific radio signals:
(1) Narrow-band signals, of order 1 Hz in width, such as would be generated as a “hailing signal” for societies wishing to announce their presence. This is the type of signal most frequently looked for by radio SETI experiments. (2) Broad-band signals that might be due to beamed propulsion within this star system. If astroengineering projects are really underway in the vicinity of KIC 8462852, one might reasonably expect the presence of spacecraft to service this activity. If these craft are propelled by intense microwave beams, some of that energy might manifest itself as broad-band radio leakage.
This is the first time we’ve used the Allen Telescope Array to look for relatively wide-band signals, a type of emission that is generally not considered in SETI searches,
said Gerry Harp.
The result? According to SETI’s Nov. 5 statement: no alien civilizations were detected, at least for now.
This rules out omnidirectional transmitters of approximately 100 times today’s total terrestrial energy usage in the case of the narrowband signals, and 10 million times that usage for broadband emissions.
While these limits are relatively high – a fact due primarily to the large distance (>1400 light-years) of KIC 8462852 – one should note the following:
- The required transmitter power for the narrow-band signals could be reduced enormously if the signal is being deliberately beamed in our direction.
- Microwave propulsion schemes would undoubtedly be beamed as well, and that would also reduce the minimum transmitter power necessary for detection by the Array.
Finally, note that any society able to build a Dyson swarm would have access to energy at a level approaching 1027 watts. Even omnidirectional transmitters would be detectable if only a tiny percentage of this energy were used for signaling.
Even if the observations are continuing, certainty is, you can stop worrying about an alien invasion from KIC 8462852.
The history of astronomy tells us that every time we thought we had found a phenomenon due to the activities of extraterrestrials, we were wrong,
Seth Shostak said in a statement.
But although it’s quite likely that this star’s strange behavior is due to nature, not aliens, it’s only prudent to check such things out.
Not all hope is lost, the proponents of the ET hypothesis — astronomers Tabetha Boyajian, Jason Wright & Andrew Siemion — would listen to the star’s radio emissions but in a different way.
The [Allen Telescope Array] results do not change our plans at Green Bank,
Wright told Popular Science in an email.
The Green Bank telescope is thousands of times more powerful than the ATA, so it will be able to make much more sensitive measurements than the ATA can.
It also covers a much wider bandwidth (up to 115 GHz) and can search for a much broader range of signal types.
The work can be found at arxiv.org. So, what do you think? Is it aliens or natural phenomenon? Tell us in a comment.