KIC 8462852 continues to dance for us, as NewScientist (27 May 2017) notes:
On 19 May, Tabby’s star began to dim, carrying on its history of strange dips in brightness. Astronomers are scrambling to decipher the mysterious signal from the star, which is 1300 light years away in the constellation Cygnus.
Back in January 2017 Phys.org published a possible explanation for unique phenomenon:
But in what may be the greatest explanation yet, a team of researchers from Columbia University and the University of California, Berkley, have suggested that the star’s strange flickering could be the result of a planet it consumed at some point in the past. This would have resulted in a big outburst of brightness from which the star is now recovering; and the remains of this planet could be transiting in front of the star, thus causing periodic drops.
For the sake of their study – titled “Secular dimming of KIC 8462852 following its consumption of a planet”, which is scheduled to appear in the Monthly Notices of the Royal Astronomical Society – the team took the initial Kepler findings, which showed sudden drops of 15% and 22% in brightness. They then considered subsequent studies that took a look at the long-term behavior of Tabby’s Star (both of which were published in 2016).
They then attempted to explain this behavior using the Kozai Mechanism (aka. Kozai Effect, Lidov-Kozai mechanism), which is a long-standing method in astronomy for calculating the orbits of planets based on their eccentricity and inclination. Applied to KIC 8462852, they determined that the star likely consumed a planet (or planets) in the past, likely around 10,000 years ago.
This process would have caused a temporary brightening from which the star is now returning to normal (thus explaining the long term trend). They further determined that the periodic drops in brightness could be caused by the remnants of this planet passing in high-eccentricity orbits in front of the star, thus accounting for the sudden changes.
Shifting back to current time, Science is reporting something interesting:
The first sign of the star’s recent dimming came on 24 April from Tennessee State University’s Fairborn Observatory in southern Arizona. But it wasn’t until late last week that astronomers were sure it had entered a new dip. It was 3% dimmer than its normal brightness on 19 and 20 May and is now moving back toward normal. “It looks like the dip has mostly ended,” Kipping says. “But … in the Kepler data we saw an episode of multiple dips clustered together over the span of a few weeks.” The progress of the dimming over the past few days also bears a passing resemblance to some detected by Kepler, supporting the idea that the same object is repeatedly passing in front of the star.
Thus the suggestion of debris. It’d have to be an enormous amount.
