The star that was thought to have been harvested by an alien megastructure is even more mysterious than we assumed. Previously, it was found that KIC 8462852 in the constellation Cygnus underwent a short, non-periodic dimming event but a new study says that it has actually dimmed slowly and steadily during the four years it was observed by NASA’s Kepler space telescope.
The findings, which are to be published in the Astrophysical Journal, show that the star has dimmed by nearly one percent during the first three years of the Kepler mission. Furthermore, the brightness of KIC 8462852 decreased by two percent within just six months. This remained the same for the last six months of Kepler’s mission.
“The steady brightness change in KIC 8462852 is pretty astounding,” says Ben Montet from the California Institute of Technology. “Our highly accurate measurements over four years demonstrate that the star really is getting fainter with time. It is unprecedented for this type of star to slowly fade for years, and we don’t see anything else like it in the Kepler data.”
Montet, together with Carnegie Institution for Science’s Josh Simon, analyzed Kepler calibration images that were not used for any scientific measurements. These results were then compared to over 500 similar stars, also observed by the spacecraft, and although the researchers found that a few of them faded during Kepler’s mission, none of them dimmed significantly like KIC 8462852.
Previously, the star’s dips in brightness were thought to be caused by an alien megastructure harvesting its energy. Another study released last year also speculated that the destruction of a family of comets or the breakup of a planet passing in front of the star caused a cloud of dust and debris that blocked some of its starlight seen by Kepler.
However, the new study indicates that these theories do not explain the long-term dimming observed during Kepler’s mission. As for the alien megastructure, Massimo Marengo, an associate professor of physics and astronomy at Iowa State University, says that they cannot say if it is real or not because they did not look for it. Still, the star suggests that there may be some new physical explanations or concepts waiting to be found.