The controversy over the ‘alien megastructure’ star (aka KIC 8462852, ‘Tabby’s Star’, and Boyajian’s Star) has raged in the few short years since it was noticed that the light it is emitting has periodically dimmed – a pattern that doesn’t show up anywhere else in astronomy, across 150,000 stars surveyed.
If the topic is new to you, work your way through the ‘Related Stories’ links at the bottom of this post, as we’ve been covering it for a while now. Or, for the tldr; crowd, here’s the Wikipedia summary:
Unusual light fluctuations of the star were discovered by citizen scientists as part of the Planet Hunters project, and in September 2015 astronomers and citizen scientists associated with the project posted a preprint of a paper on arXiv describing the data and possible interpretations. The discovery was made from data collected by the Kepler space telescope, which observes changes in the brightness of distant stars to detect exoplanets.
Several hypotheses have been proposed to explain the star’s large irregular changes in brightness as measured by its unusual light curve, but none to date fully explain all aspects of the curve. The leading hypothesis, based on a lack of observed infrared light, posits a swarm of cold, dusty comet fragments in a highly eccentric orbit. However, the notion that disturbed comets from such a cloud could exist in high enough numbers to obscure 22% of the star’s observed luminosity has been doubted. Another hypothesis is that of a large number of small masses in “tight formation” orbiting the star. However, spectroscopic study of the system has found no evidence for coalescing material or hot close-in dust or circumstellar matter from an evaporating or exploding planet within a few astronomical units of the mature central star. It has also been hypothesized that the changes in brightness could be signs of activity associated with intelligent extraterrestrial life constructing a Dyson swarm.
Now, the controversy over the star looks set to be reignited – and hopefully answers to the mystery uncovered – with news that it has just started dimming again. Astronomers are, understandably, a wee bit excited about this:
The dimming event is still underway as I write, so it’s still very early days in terms of looking for patterns and answers. However, the following graph posted by @David_Kipping shows an interesting comparison between the public observations of the star so far to a previously recorded dipping event.
To keep up to date with developments related to this new dimming event, it is probably worth checking out the ongoing discussion currently taking place on a Reddit board devoted to KIC 8462852. Also, last night Tabetha Boyajian participated in an online Q&A about the new observations currently underway, which I’ve embedded below for those interested: