A group of scientists from the University of California at Berkeley searched for technosignatures (signs of advanced technologies) in the star KIC 8462852 (Tabby's star). Some experts suspect that megastructures built by an alien civilization revolve around this luminary, unusual for its aperiodic changes in brightness. Astronomers have recorded several anomalous signals, which they described in a preprint published in the arXiv repository.
The researchers studied 177 high-resolution spectra of Tabby's star, taken with the Automated Planet Finder telescope at the Lick Observatory (USA) and covering the wavelength range from 374 to 970 nanometers. They looked for traces of laser radiation with a power of more than 24 megawatts, which is the lower limit of the sensitivity of the device, taking into account the distance to the object in 1470 light years. The algorithm developed to do this analyzed each spectrum pixel by pixel to find hard-to-see emission lines that might arise from lasers.
In total, scientists have identified 58 candidate signals that could arise from the activities of alien civilizations. Upon further analysis, the researchers checked to see if the signals had any other explanation, including cosmic rays hitting the telescope's detectors, the intrinsic glow of the atmosphere, and random fluctuations in the stellar spectrum. It turned out that all the anomalous spectral lines most likely arose from natural causes, and not from lasers.
According to scientists, despite the negative result, their work lays the foundation for the further search for alien technosignatures associated with laser technologies. To increase the likelihood of detecting alien civilizations, the spectra of stars of various types, including those that look like the Sun, must be analyzed.
The star Tabby is known for its luminosity changes in 2015. The star's brightness dropped by 22 percent at different intervals. Some scientists have suggested that the reason for this may be a giant astro-engineering structure built by an extraterrestrial civilization, such as the Dyson sphere. However, at present, astronomers are inclined to believe that the anomalous behavior of the star is explained by a cloud of dust or other celestial bodies of natural origin.
