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Tabby’s Star: A Deep Space Mystery Never Seen Before

by Kimberly Lin

Approximately 1,500 light years away from Earth lies a strange star exhibiting abnormalities as astronomers have never seen before. KIC 8462852, the WTF star (where’s the flux), or Tabby’s Star, as it is nicknamed, was observed by the Kepler space telescope which was launched into our solar system in 2009. Kepler’s mission is to seek out planets in our region of the Milky Way Galaxy that may potentially be habitable. However, it has detected very mysterious circumstances with the F-type star that have scientists completely baffled.

Lunar Transit Across Star Similar to Tabby's Star

A lunar transit across the sun, NASA. Tabby’s Star, similar to our sun, is being shadowed by a very large anomaly. Source NASA .com

How Kepler Identifies Exoplanets

Planets that are very far away cannot be seen even with our most powerful telescopes. In order to detect rocky objects or planets far in space, Kepler looks for the star first, since it gives off light. Objects block out light or may cause “blinks” across our field of view as the object crosses in front of the star. When something moves between us and the star it is also called a transit. Kepler’s job is to identify the changes in light coming from a star as the transit and dimming are occurring. With that data, scientists can determine the size and shape of the object.

Planets are round and normally give off specific indicators of their presence. Experts expect to see certain patterns if they are dealing with an exoplanet (a planet that orbits a star outside of our own solar system). However, in September of 2015, astronomers led by Tabetha S. Boyajian (finder of KIC 8462852), now of Louisiana State University, announced that Tabby’s Star was behaving in ways that they could not account for.

Tabby's Star shown in infrared and ultraviolet.

KIC 8462852 in infrared and ultraviolet. Source: Wikipedia, public domain.

Strange Anomalies

Dramatic Dimming of KIC 8462852

There have been transits across Tabby’s Star that have caused dramatic dips in light over the last several years. Scientists focused on two major events. One transit they call D800 was a single event that caused a large drop of brightness by 15 percent. The second event, D1500, was a sudden series of transits that together resulted in a dimming of 22 percent. It appears this was caused by a group of huge objects, though not planets, as even a large planet, such as Jupiter, would cause only about a 1 percent light decrease.

Other Mysteries

The shape of the transiting objects were irregular, whereas a planet would be round. Additionally, the dips were not in regular intervals. A transiting (orbiting) planet causes regularly interval blinks across our field of view and diminished light could last for hours. However, Tabby’s Star showed a decrease in light that lasted for days.

Dimming Over Time

In addition to these strange behaviors, another anomaly has scientists puzzled. It appears that Tabby’s Star is slowly fading over time. This, according to Ben Montet, of the California Institute of Technology in Pasadena, is “unprecedented for this type of star.” In January of 2016, “astronomer Bradley Schaefer of Louisiana State University reported that KIC 8462852 also seems to have dimmed overall by 14 percent between 1890 and 1989” (Space.com). He determined this by evaluating photographic glass plates that had captured KIC 8462852 between that time period in the Harvard College Observatory.

Related: The Boötes Void – A Patch of Space With Few Stars

However, Montet and another scientist doubted his findings. They theorized that the results must be due to the changing technological levels of the instrumentation over the years. However, Montet and Simon, of the Observatories of the Carnegie Institution of Washington, attempted to see if they could find any basis for Schaefer’s claims by looking at the Kepler data collected between 2009 and 2013. Tabby’s Star brightness decreased by a total of 1 percent over the first 3 years. Then, over the next 6 months, it dimmed more dramatically by 2 percent for a total dimming of 3 percent. In the last 6 months of Kepler’s observation, the star remained stable. No other stars they observed dimmed so quickly.

Theories About the Mystery

Large Dust Clouds, Collision Debris, or Comet Fragments

Scientists began to brainstorm to come up with possibilities as to what may be causing the odd events. They thought perhaps it was a large disk of dust, but they determined it couldn’t be this because there was no evidence to support the idea. Another theory was that a planetary collision may have caused debris that is obstructing the star’s light. Again, the evidence was lacking.

Another theory that seems plausible is that the mass of objects are large comets from another enormous celestial body that broke up in the powerful gravitational pull of the star. However, scientists don’t believe comets could have affected the longterm dimming seen over the last century.

Tabby’s Star Alien Megastructure

The most interesting and sensational theory brought up by astronomers involves an alien megastructure. Something like the Dyson Sphere or Dyson Swarm, which is a hypothetical system of structures, could orbit around a star to collect energy. A structure like this could have the potential to power an entire planet. Scientists are so baffled and intrigued at the same time, that the Breakthrough Listen initiative has begun to look toward KIC 8462852 for alien signals. The organization is connected to the Berkeley SETI project, and they have a $100 million, 10-year appropriation to fund the search. Although scientists indicate that the chance of this mystery stemming from alien life is 1 out of a billion, the enthusiasm is high.

Illustration Tabby's Star alien megastructure

Illustration of solar megastructure collecting energy around star. Source: Youtube.

The Wait for Results

The “most mysterious star in the galaxy” has strange, irregularly shaped transits that block an enormous amount of light. It also has an irregular pattern of fading over the last century, and an unexplained increased rate of dimming which levels out again. Is it possible these strange events are not related? Scientists think it’s not likely. Chances are there is one explanation for these unprecedented anomalies.

The Tabby’s Star mystery has commanded the attention of many organizations and scientists around the world who are eagerly investigating. Now we can sit back, look up at the stars, and wait for answers.

Astronomy Now
Sky and Telescope
NASA Kepler

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