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No alien megastructure for Tabby’s Star

This star’s odd, sporadic dimmings and brightenings caused speculation about vast structures built by alien civilizations. But a crowd-funded observing campaign led to a different conclusion.

Tabetha Boyajian has been the driving force behind bringing the mysterious star KIC 8462852 – aka Tabby’s Star or Boyajian’s Star – to public attention. Image via exoplanets.astro.yale.edu

A few months ago, a team of astronomers using space-based observations said the weird and dramatic dips in brightness in the otherwise ordinary star KIC 8462852, aka Tabby’s Star, were probably caused by dust. This star is located some 1,000 light-years away. It caused an uproar in the fall of 2015, when astronomers first announced its strange up-and-down light pattern and began speculating about a possible Dyson sphere or megastructure around the star, built by an advanced civilization with the goal of large-scale energy harvesting. Today (January 3, 2018) – aided more than 1,700 people who donated over $100,000 through a Kickstarter campaign – a team of more than 200 researchers using ground-based observations announced that they agree. Yes, they said, the strange dimmings and brightenings of Tabby’s Star are due to dust, not aliens.

Astronomer Tabetha Boyajian, formerly at Yale and now at Louisiana State University, is the person for whom Tabby’s Star is named. She also led the crowd-funded study, which published in the peer-reviewed Astrophysical Journal Letters.

Jason Wright at Penn State University is a co-author on the study. He said:

We were hoping that once we finally caught a dip happening in real time we could see if the dips were the same depth at all wavelengths. If they were nearly the same, this would suggest that the cause was something opaque, like an orbiting disk, planet, or star, or even large structures in space.

Instead, the team found that the star got much dimmer at some wavelengths than at others, suggesting dust as the most likely explanation.

The scientists closely observed the star via the global network of Las Cumbres Observatory from March 2016 to December 2017. Beginning in May 2017 there were four distinct episodes when the star’s light dipped. They wrote:

They’re almost certainly caused by something ordinary, at least on a cosmic scale. And yet that makes them more interesting, not less. But most of all, they’re mysterious.

Artist’s concept of a hypothetical uneven ring of dust causing the mysterious dimming of the star KIC 8462852, also known as Boyajian’s Star or Tabby’s Star. Image via NASA/JPL-Caltech.

It makes them more interesting to professional astronomers, probably. But – to the rest of us – dust just can’t match an alien megastructure for glamor. Yet – as speculation about Tabby’s Star and an alien megastructure had its day – Tabetha Boyajian herself performed a service for astronomy and for those of us who love it. Her Ted Talk titled The Most Mysterious Star in the Universe drew many into astronomy’s wonderful perplexities. And Boyajian ran a heck of a good Kickstarter Campaign, giving people a chance to participate in science, and keeping those who donated informed every step of the way via frequent updates. She said, by the way:

It’s exciting. I am so appreciative of all of the people who have contributed to this in the past year — the citizen scientists and professional astronomers. It’s quite humbling to have all of these people contributing in various ways to help figure it out.

And we’re appreciative of you, Tabby! Thanks for a great story, and for letting the rest of us come along for the ride.

Read more about Tabby’s Star in these blogs by Jason Wright:

What We’ve Learned about Boyajian’s Star, Part 1

What We’ve Learned about Boyajian’s Star, Part 2

Andrew Siemion, director of the Berkeley SETI Research Center, explaining the megastructure theory of Tabby’s Star. In this theory, the dimming of the star was caused by an alien-built structure.

Bottom line: The mysterious dimmings and brightenings of an otherwise ordinary star – called KIC 8462852, aka Tabby’s Star or Boyajian’s Star – is likely caused by dust, according to astronomer Tabetha Boyajian and her team.

Source:
The First Post-Kepler Brightness Dips of KIC 8462852

Deborah Byrd

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