Last year KIC 8462852 (Tabby’s Star) made headlines as a possible - although far fetched - candidate for an alien mega-structure. While there isn’t yet any evidence of this audacious hypothesis, I thought it would be a good idea to explain why this star is so unique and also give an update on the current science being done to study the star. Aliens or not, it’s a fascinating story. So sit back, relax, and prepare to hear one of the greatest tails in modern scientific history.
In the beginning the telescope Kepler was launched into space to look for exoplanets. And it looked upon thousands and thousands of stars and found many new worlds - and the scientist called it good. For the wealth of knowledge that the Kepler wrought was worth far more than a thousand earth based telescopes combined. And all was right and well within the scientific community.
But there was one scientist who noticed something irregular in the vast troves of data. Brought to her attention by citizen scientist - she realized there was one star unlike any other star seen in the entire universe. It was dimming up to 20% of its output for days and weeks at a time. And the dimming was happening in irregular and lopsided intervals. And this astronomer, Tabetha Boyajian, was skeptical of what she saw and thought the data was surely corrupt. Because KIC 8462852 was a main sequence star (type F to be exact) and much like our Sun (Type G) it should be highly stable in its energy output.
So she and her team sought to find the culprit in the data. But no culprit could be found and they soon realized the data was in fact sound. So Tabby sought an explanation for such a large and irregular dip.
At first she thought it could be caused by a large accretion disk - but the star was too old to still have such baby features and there was no infrared signal coming from the star system that such a disk would put out. Next Tabby thought it could be the remnants of a broken up comet - but the dip was too large and the intervals didn’t match up. Next she thought it might be the aftermath of the collision of two planetary bodies or a runaway chain reaction in a tightly packed asteroid belt - but both those explanations would also be measurable in the infrared - and there was no such infrared signal to be found. Her colleagues even considered that the stars dimming could be caused by one or more dust enshrouded planetesimals - but this was ruled out as well. Finally, Tabby reasoned the data could only be explained by a massive swarm of comets in multiple and highly elliptical orbits. And she was at peace with this explanation.
But there was another scientist. And his name was Schaefer. And Schaefer looked at the archive of photographic plates taken of KIC 8462852 over a period of a century from 1890 to 1989. And Schaefer saw that Tabby’s star for the past century has been dimming by an average of of 0.165 ± 0.013 mag century−1 (or 0.152 ± 0.012% yr−1). And this dimming could not be explained by swarms of comets. And the dimming was not how main sequence stars behaved.
It must be understood that the longer a main sequence star burns - the hotter and brighter it becomes as it fuses heavier and heavier elements doing so all the way up to iron - at which point fusion can no longer take place and the star swells into a massive red giant. But Tabby’s Star was not warming up 1% every 100-million years as main sequence stars should. Rather, in the past 100 years, the star had dimmed by several percentage points. And it was the work of Dr. Schaefer that showed this to be so.
But many in the scientific community did not like this new and unsettling information. And some sought to dispute Schaefer's findings. And they called into question the statistical accuracy of the photographic plates from which he had gathered his information. And many were convinced that Schaefer’s findings were not sound. And, in the media, his work was openly discredited. And it was a sad time for Bradley Schaefer.
But then astrophysicist Benjamin Montet came to Schaefer’s rescue. Dr. Montet and his colleague, astronomer Josh Simon, looked at the four years of observations taken by the Kepler Telescope of the star KIC 8462852. And they showed, conclusively, that the star, over a function of time, was in fact dimming. And Schaefer’s work was vindicated. And the mystery of Tabby’s Star deepened. For no one could produce a viable natural explanation for why this star was dimming over the years. Nor why it would periodically dim up to 20% for days and weeks at a time.
So Tabetha Boyajian took this up this question as her mantel. Knowing that NASA wouldn’t jump to pursue such a high risk / high reward mission and also knowing that it could take years for her to secure funding from the National Science Foundation - she instead chose to start a kick-starter. And Tabetha raised over $100,000 for he cause. And she used this money to purchase observation time from the Las Cumbres Observatory Global Telescope Network. And, starting in August of 2016 and continuing all the way to December 2017, she will monitor KIC 8462852. And when dips occur again she will be ready to measure its spectrum. And this will tell her what kind of material that is passing in front of the star and she will be able to more accurately measure the rates of the dips. And, after he work is concluded, she will put forth a better and more informed hypothesis to explain the mystery that is Tabby’s Star.
And many of us today are holding our breath - silently hoping that her explanation is attributed to a massive extraterrestrial engineering project. While this is the most unlikely of all the possibilities - it is also the most interesting. And, as of today, the mystery of Tabby's Star remains. And the mystery is good.