Free Astronomy Magazine September-October 2024

8 SEPTEMBER-OCTOBER 2024 ASTRO PUBLISHING I n these illustrations, we see two possible scenarios for the anomalous photomet- ric behavior of KIC 8462852, a main-se- quence star (F-type) located in the constel- lation Cygnus, about 1500 light-years from Earth. For a short time, this object was a candidate for a Dyson sphere, but it is much more likely that the star was partially obscured by a swarm of comets or by a de- bris disk with irregu- lar density. [NASA, JPL-Caltech] abundant for their spectral class or stars with unusual photometric be- havior if the hypothetical megas- tructures were not complete shells. Something of the sort hit the head- lines in 2015, when one of the stars monitored by the Kepler Space Tel- escope, KIC 8462852 (better known as Tabby’s Star), showed brightness fluctuations consistent with a large mass orbiting around it. Careful fol- low-up observations then ruled out an excess of infrared radiation, lead- ing astronomers to lean towards a natural cause of the phenomenon, such as an inhomogeneous circum- stellar disk of rocky debris and ice, or, alternatively, intrinsic variations in the stellar photosphere. The disappearance of the most promising Dyson sphere candidate has obviously not discouraged the most assiduous hunters of those hy- pothetical engineering works. In recent years, there has been no shortage of contributions from ex- pert research teams, such as Project Hephaistos (a name inspired by the Greek god of fire, forges, engineer- ing, sculpture, and metallurgy), which is based at Uppsala University, Sweden, and has collaborators in the USA, UK, and India. The most re- cent contribution from Project Hephaistos, en- titled “Dyson sphere candidates from Gaia DR3, 2MASS, and WISE,” was published in the Monthly Notices of the Royal Astronomical Soci- ety last June by a team including lead author Matías Suazo (Depart- ment of Physics and As- tronomy, Uppsala Uni- versity). The team used the im- pressive databases of those three surveys, searching for astrophys- ical objects with spec- tral, photometric, and