New measurements suggest Tabby's Star has a "complicated" relationship with another star. These interactions could explain these irregular drops in luminosity.
Located 1,470 light-years from Earth in the constellation Cygnus, KIC 8462852 (or "Tabby's Star") is an intriguing star. Discovered in 2015, it was indeed quickly illustrated by irregular and unpredictable drops in its luminosity , with dips sometimes reaching 22%. These behaviors exclude the presence of one or more planets. When an exoplanet passes between a star and the Earth from our point of view, the dips in brightness are indeed much less marked – 1% or less – and appear at regular intervals.
We also know that some wavelengths are blocked more than others during these dimming events. For the vast majority of researchers, this excludes the hypothesis of the presence of a solid object (such as an extraterrestrial megastructure, proposed as early as 2016), which would normally block all wavelengths in the same way.
Finally, the most likely explanation for these types of events is that Tabby's Star is surrounded by dust or coarser debris , from disintegrating comets or colliding asteroids. A recent study now reinforces this idea.
For several years, a team from the University of Arizona, led by Logan Pearce, has been trying to confirm the presence of a binary companion to KIC 8462852. As part of this study, accepted for publication in The Astrophysical Journal , the researchers relied on the Keck telescope (Hawaii) and data from the European satellite Gaia to make precise astrometric measurements of the faint star which seemed close to KIC 8462852.
These works confirmed the presence of this stellar companion. The two stars are separated by a distance of 880 astronomical units, about 132 billion kilometers . Tabby's Star, now called KIC 8462852 A, is the larger of the two stars, with about 1.36 times the mass and 1.5 times the size of the Sun. Its companion, KIC 8462852 B, is a red dwarf star about half the size and mass of the sun.
With such a large orbit it is unlikely that KIC 8462852 B has a direct effect on the luminosity of KIC 8462852 A. On the other hand, it could still play a role in the luminosity fluctuations observed from Earth, believe the researchers.
Previous computer simulations have indeed already shown that these systems can be very sensitive to gravitational influences, eventually regularly moving very close to each other's center of mass. This could result in the disruption of small orbiting bodies, stretched and torn apart by these gravitational interactions, ultimately leading to the formation of clouds of debris.
At this time, researchers believe this is the most likely explanation. However, future measurements will be necessary to better understand the relationship maintained by these two stars.
