Last week, Dr Tabetha Boyajian and her team announced that the mysterious star KIC 8462852, otherwise known as Tabby's star, was back to its old tricks when it started experiencing deep dips in brightness, reducing the light we receive from the star by 4 percent. This week, they announced that the object experienced a new dip, this time of 5 percent. This is the deepest one since the original observations of the star by the Kepler Space Telescope a few years ago.
These dips in brightness indicate the presence of a planet, and this is the approach that Kepler uses to find exoplanets. KIC 8462852 has previously had light dips of 15 and 22 percent, which left people baffled. To this day we still don’t know what created those dips. Exotic theories, like an alien megastructure, or more reasonable ones, like comet swarms, have all failed to explain what was going on.
In fact, Tabby’s star has been so defiantly puzzling that Dr Boyajian and her team started a Kickstarter campaign to raise money to continue monitoring it once Kepler moved onto other objects. We might not have a solution yet, but the campaign is clearly bearing fruit. These dips are important new pieces of the puzzle.
“Today we have some very big news – data taken at TFN last night show the flux is down 5 percent," Dr Boyajian and her team wrote in an announcement post. "This drop has now been confirmed by AAVSO [American Association of Variable Star Observers] observer John Hall. Looks like we beat the record set just last week on the deepest dip observed since Kepler!”
So what is causing the dips? The main contender for an explanation is dust. The star might be surrounded by a large donut of stellar dust. It would be patchy rather than uniform, which would explain the dissimilar dips that have happened at random intervals. If this is the case, continuous monitoring might reveal some more details about the properties of this apparent ring of dust.
Tabby’s star was at first called the WTF star. WTF, as you all know, stands for Where's The Flux? – a common exclamation for astronomers observing stars whose fluxes seems to disappear in deep and unexpected dips. Whatever you call this star, it is undeniable that it's at the center of a fascinating mystery.