I rather like it when scientists come up against something they can’t understand. Tabby’s star is one such conundrum. It’s behaviour is – pun intended – out of this world.
One of the ways in which astronomers search for exoplanets is to see if the brightness of a star dips as a planet moves in front of it. Such dips are quite small and quite regular, matching the orbit and size of the exoplanet. Except for Tabby’s star. Hundreds of exoplanets have been discovered by this method, and they all display the nice regularity I’ve described. Except for Tabby’s star.
It’s light dips massively above the 1% a Jupiter sized planet moving in front of it would cause; as much as 15% and 22% have been recorded. The equivalent of something massive enough to obscure half of the surface area of the star. And when it does brightens again, that too is not as expected. Instead of the dip and the rise being the same shape, as current theory says it should, they do not match. Furthermore even the occurrence of these dips is irregular, and difficult to explain. Finally, to add to the mystery, apparently Tabby’s star has been getting progressively dimmer over the last 100 years or so, (the star was first observed in 1890).
The name “Tabby’s Star” or “Boyajian’s Star” refer to the initial study’s lead author, Tabetha S. Boyajian. The star’s proper nomenclature is KIC 8462852. It didn’t show up in a computer led search for exoplanets, and was found by good old fashioned humans. These same humans have come up with many explanations for the behaviour of the star, including of course, aliens at work. But currently there are no explanations that fit the observations. Although there are a lot of astronomers working on the puzzle and trying to come up with said explanations. Just google “Tabby’s star” and see.
Which I rather like! One little pointer to the fact that we still have a lot to learn about this Universe that we live in!!