WTF is up with KIC 8462852 the WTF Star?

The KIC 8462852 star (aka the WTF ‘Where’s The Flux?’ star) continues to baffle scientists and ignite dreams of alien civilizations.

KIC 8462852 imaged with a ground-based 17″ telescope: image credit Bellatrix Astronomical Observatory


There is a lot of odd things we have seen in space that can make astronomers re-think their view of the Universe. One such oddity is a star within our galaxy called KIC 8462852. This star near the constellation Cygnus is a member of the Kepler Input Catalog – hence the KIC designation.


Kepler Space Observatory
Kepler Space Observatory in a clean room at Ball Aerospace & Technologies. (credit: NASA/JPL-Caltech/Ball

Kepler’s Hunt for Planets
Kepler is a space observatory launched in 2009 that is specifically designed to find planets in an area of our galaxy between the constellations Cygnus, Lyra and Draco. By constantly measuring the brightness of over 145,000 stars, Kepler can tell us when a star dims due to an orbiting planet passing in front of it. By measuring the magnitude and speed of repeated dimming of a star as a planet whirls around it, we can calculate the size of the planet and how far it orbits from its host star.

So far Kepler has performed admirably by finding over 1000 planets and has another 3000 planetary candidates awaiting more detailed observation to confirm their existence. Due to Kepler’s findings over the last five years, we now think there should be as many as 40 BILLION earth-sized planets just within our own galaxy.


A Star’s Luminosity vs its Apparent Magnitude
One of the stars that Kepler observed (KIC 8462852) is unlike all the rest. It has been affectionately tagged as the ‘WTF Star’ due to the research paper ‘Where’s The Flux?’ written by Tabetha Boyajian, an astronomer at Yale University who leads the study.

Most stars gradually change in brightness (or apparent magnitude) over regular cycles. Our own Sun has a 0.1% change in brightness over an 11-year cycle. Some stars swell and contract on regular cycles that may last many years long or cycle in fractions of a second. Then there are some stars that change in brightness in our sky as other stars, planets and other objects move in front of them.

Apparent Magnitude is the brightness of a star as seen from an observer on Earth. Don’t confuse this with the luminosity of a star which is a measure of the star’s total energy output. A very luminous star that is far from Earth will have a very low magnitude when viewed in our skies.

To confuse matters more, the magnitude scale assigns lower numbers to brighter objects. The Sun has the highest magnitude on the scale at -26.7, the full moon is second at -12.6. The human eye can see stars down to a magnitude of +6.0 and the faintest objects seen by the Hubble Space Telescope have a magnitude of around +30.0.

All these changes in the apparent magnitude of stars right across the Universe have one thing in common, they all occur at somewhat regular intervals. What makes KIC 8462852 unique is that its apparent magnitude is changing by large degrees and at very odd and irregular intervals.


WTF is going on out there?

Going through Kepler’s observations of the star between 2009 and 2014, Tabetha’s team in September 2015 noticed that KIC 8462852 (also now known as ‘Tabby’s Star’) was dimming by as much as 20% of its apparent magnitude. They knew that no planet orbiting the star could block that much light. Even a gas giant bigger than Jupiter in orbit around KIC 8462852 would only reduce the stars brightness by 1% at most.

Graph of KIC8462852 showing dips in brightness
Kepler’s graph of KIC8462852 showing dips in brightness over an 1600-day observation period. (credit: Boyajian et al)

More puzzling was that over an observation of 1500 days, the star’s brightness was changing at irregular intervals and at irregular rates. Around Day 800 of observation the star suddenly dimmed by 15% in brightness for about 24 hours before returning to normal. Then on Days 1520 to 1580 it dimmed a half a dozen times by as much as 20% before going back up to its original brightness.

After this discovery, follow-up observations were made by the Boquete Optical SETI Observatory in Panama and by Allen Telescope Array (ATA) in California over November 2015. These telescopes were looking and listening in the area around KIC 8462852 to see if they could detect any radio waves or laser light emanating from the star.

Why radio waves and laser light? Because some believe that these two mediums could be used for communication by an advanced civilization. That’s right – I’m talking about aliens.


ET Phones Home – No Dial Tone
The behavior of the KIC 8462852 is so unique and head-scratching that shortly after the findings were published, some members of the scientific community believed that intelligent life may be behind this star’s dimming.

SETI's Allen Telescope Array
Allen Telescope Array (ATA) at the Hat Creek Radio Observatory outside of San Francisco, California. (credit: The SETI Institute)

One theory believes that most advanced civilizations will have an increasing need for tremendous amounts of energy to drive their civilization upwards and outwards. The closest and most abundant source of energy would come from the star that their planet orbits. If an advanced civilization could build massive energy collectors that would closely orbit their star, we would see the star dim in intervals and at levels we could not explain through natural phenomena. Just like what we were seeing with KIC 8462852.

Unfortunately after a month of observation neither telescope found any traces of energy related to an advanced civilization. If there are aliens around KIC 8462852, they are using other undetectable ways to communicate. Another theory that was put forward is that perhaps a family of comets and debris passed in front of KIC 8462852, causing its light to dim from our perspective. But after calculating the orbit and size of any object that could dim the star by 20% the numbers just didn’t add up.

Unfortunately Kepler suffered failures to some of its orientation systems in May 2013 and has been unable provide any more data about KIC 8462852. But due to Tabetha’s discovery we now have multiple ground-based telescopes monitoring the star in Kepler’s absence waiting for the next great dimming.


A Clue from the Past
Not content on waiting for future events to unfold, researches have combed through past observations of the region of the sky around KIC 8462852 to see if anything odd was ever recorded but not yet uncovered. One such researcher named Bradley Schaefer from Louisiana State University has just made a recent discovery by meticulously going through archives of the area dating back to 1890. By analyzing old photographic plates that happened to have captured the star, he has calculated that the star was brighter by 20% over a century ago.

In his paper submitted Jan 2016 Bradley states “The century-long dimming and the day-long dips are both just extreme ends of a spectrum of timescales for unique dimming events, so by Ockham’s Razor, all this is produced by one physical mechanism. This one mechanism does not appear as any isolated catastrophic event in the last century, but rather must be some ongoing process with continuous effects. Within the context of dust-occultation models, the century-long dimming trend requires 10^4 to 10^7 times as much dust as for the one deepest Kepler dip. Within the context of the comet-family idea, the century-long dimming trend requires an estimated 648,000 giant comets (each with 200 km diameter) all orchestrated to pass in front of the star within the last century”.

In summary, Bradley believes that this phenomena has been going on for over a century, a time too long to be explained by a random passing of comets or other objects.

So is it aliens? Most likely not. A majority of astronomers believe intelligent life is out there just based on the sheer vastness of the Universe. But we also rely on diligent observation and rigorous proof of theory. It seems for now that we need to wait for the next dimming of KIC 8462852 to occur so we can hopefully discover a new clue to help solve this mystery.

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