A new clue has just been found that could help solve the mystery of a strangely darkening star. KIC 8462852, also known as Boyajian star, appears to have a binary companion that could contribute to its irregular brightness drops.
If confirmed with more detailed observations, the newly discovered companion star could help astronomers finally solve the ongoing mystery of KIC 8462852.
The star was discovered in 2015 by astronomer Tabetha Boyajian (so she used to be Tabby’s star) and has since proven to be a true puzzle. It is a white and yellow dwarf star about 1,470 light-years away and remains dimming irregularly. There is no regularity either at the time of star darkening or at depth; some of the falls in the light of the stars have been as deep as 22%.
This behavior rules out the planets; when an exoplanet passes between a star and Earth as it orbits, it will attenuate the star a small amount (1% or less) at regular intervals.
Also, when the Boyajian star shrinks, some wavelengths are blocked more than others. This rules out a solid object (such as an alien megastructure, as proposed in 2016), which would block all wavelengths equally.
So far, the most likely explanation appears to be optically thin dust and debris, possibly from planetesimals or comets broken into eccentric orbits, in combination with normal variations in brightness from the same star.
The presence of a binary companion star in a wide orbit could help explain the presence of all this material, providing additional gravitational perturbations to upset bodies in orbit.
Since 2016, a team of astronomers led by Logan Pearce of the University of Arizona has been trying to confirm the potential connection of a nearby star to KIC 8462852. His work has been accepted at The Astrophysical Journal.
The difficulty of measuring space in three dimensions is what has made this work quite hard. Stars that look quite close together can be at very different distances from the viewer. Therefore, Pearce and the team used five-year observations to make accurate astrometric measurements of the faint star that appeared close to KIC 8462852.
“In this work we use three epochs of Keck / NIRC2 astrometry spanning five years to review the status of the close companion to KIC 8462852 and show that they are a common proper motion pair and a gravitationally bound binary system,” they wrote in your document. paper.
In addition to observations from the Keck Observatory, the launch of astrometric data from the Gaia satellite in 2020, the most complete and accurate three-dimensional map of the Milky Way to date, also included the faint star, with measurements of according to the team’s findings.
The two stars are separated by a distance of 880 astronomical units. The Boyajian star, or KIC 8462852 A, is the largest star, about 1.36 times the mass and 1.5 times the size of the Sun. The companion, KIC 8462852 B, is a red dwarf star about 0.44 times the mass and 0.45 times the size of the Sun.
In such a wide orbit, KIC 8462852 B is unlikely to have any direct effect on the brightness of KIC 8462852 A. But it could still play a role in the mysterious fluctuations of the larger star, the researchers said.
“The binary companion can influence the long-term evolution of the system,” they wrote in their article.
Scientists have previously discovered that larger gravitational forces can push widely spaced stellar binaries to move very close to their center of mutual mass several times over about 10 billion years.
In turn, this could cause the interruption of planets and other small bodies in orbit where they stretch and break due to gravitational interactions, resulting in debris clouds.
The scenario is yet to be confirmed. In such a wide separation, the two stars would have an extremely long orbit and the observations taken were not enough to characterize this orbit. KIC 8462852 B could be a star that was ejected from the system; or the two stars could be members of a group moving together.
Researchers believe a binary is the most likely explanation for their two-star measurements, but future measurements of the pair will be needed to better understand their relationship. This could help to confirm or rule out the role of KIC 8462852 B in the erratic brightness of the star.
But, for all lovers of mystery out there, don’t be afraid. There are other stars that remain weird, including a star for which the binary companion has already been explained and a captivating collection of 21 stars that could be even weirder.
Team investigation accepted The Astrophysical Journal, and is available at arXiv.