Tabby’s or Boyajian’s Star was named after Tabetha Boyajian; a pizza delivery driver turned astrophysicist whose 2015 Yale post-doc paper rocketed her to instant fame. She and her colleagues discovered that the mature yellow-white dwarf star that would bear her name exhibited extreme sporadic fluctuations in light. Her paper suggested that perhaps a swirl of intergalactic dust was to blame.
According to NBC News, “this otherwise-normal F-type star, which is slightly larger and hotter than Earth’s Sun, sits about 1,480 light-years from Earth, in the constellation Cygnus.”
Other astronomers began to hypothesize that the irregular light from the star wasn’t natural but caused by extraterrestrial activity. In the search for alien life, one prominent idea is to look for “Dyson sphere,” a hypothetical megastructure built to harness the power of a star. Could that be why the starlight was dimming?
Pennsylvania State University astronomer Jason Wright theorized that a planet-sized “alien megastructure” could be harnessing the power of the star, causing the starlight to dip by as much as 22 percent.
From the Daily Beast:
“‘When [Boyajian] showed me the data, I was fascinated by how crazy it looked,’ Wright told The Atlantic. ‘Aliens should always be the very last hypothesis you consider, but this looked like something you would expect an alien civilization to build.’
Boyajian—who believes that there’s life outside our planet—said that what excited her and simultaneously mystified her was the fact that the material blocking the star defied typical rules about exoplanet formation and star flux. ‘The amount would indicate there was a lot of stuff there,’ she said. ‘The light should hit it. We didn’t see that. The fact that an alien civilization could be doing this, that an artificial structure around the star could lead to the infrared patterns—it was an ‘aha‘ moment.'”
Excited by the possibilities, Theoretical Physicist Michio Kaku appeared on CBS News suggesting the find could be “the biggest discovery in 500 years.” He wondered if the news would be even bigger than the discovery of America or else “the biggest wild goose chase since the Loch Ness Monster.”
“There is a colossal, humongous, object of some sort blocking the starlight from this star. We’ve ruled out all of the usual suspects; rouge planets, comets, asteroids and the only thing left is an ‘alien superstructure’ of some type.”
On September 18, 2019, reports suggest a new explanation for Tabby’s Star. According to Science Alert, a celestial body called a “ploonet” could be blocking out the light.
“New research suggests that the strange brightening and dimming fluctuations of the star’s light that have been observed for years (and back-traced from archival data) could be the result of a disintegrating exomoon in orbit around the star.
Such a wayward moon – recently nicknamed a ploonet – would be shedding dust and chunks of rock that move between us and Tabby’s Star in a coalescing disc.”
Ploonets are a brand new class of hypothetical cosmic objects, a sort of cross between a moon and a planet. They are exoplanets that have been kicked out of a gas-giant planet’s orbit, breaking free of the gravitational bonds. Some ploonets are thought to begin orbiting the nearby star, while others crash into the planet or are shot out into the solar system.
This scenario may be why astronomers haven’t found evidence of exomoons. (They largely end up broken to bits.)
Observations of the light from Tabby’s Star reveal that some wavelengths are blocked more than others. So, a solid planet-sized object like a Dyson sphere is probably not the cause. However, it may not rule out the possibility of a so-called “Dyson swarm.”
According to Futurism, constructing a collection of solar-collection devices would be far easier to construct than a single vast megastructure.
“…making a single vast megastructure encapsulating the Sun is structurally impossible.
“‘We’d be faced with gravitational stresses, structural in-habitability, and location instability. Moreover, we currently ‘don’t have the engineering capabilities nor the materials to pull this off.
But collecting the entire output of our home star may still be the smart choice. What we do instead is to build a Dyson ‘swarm,’ and not a Dyson ‘sphere.’ The Dyson Swarm is made up of one-kilometer (0.6 mi) solar panels that orbit the Sun in hundreds of stable criss-cross patterns.”
Of course, Tabetha Boyajian’s original idea that exocomets block the starlight can’t be ruled out, but it would take an extraordinary amount of such dust and comets. This has led researchers at Columbia University to suggest that a ploonet is the source for the debris. If so, the ploonet is being slowly obliterated to bits by the star, evaporating over millions of years.
Astrophysicist Brian Metzger of Columbia University explained:
“Eventually the exomoon will completely evaporate, but it will take millions of years for the moon to be melted and consumed by the star. We’re so lucky to see this evaporation event happen,” said Metzger.
Until quite recently, testing Metzger’s hypothesis would be thought impossible. Tabby’s Star was the only one exhibiting the odd patterns of dimming light. However, a new study by Edward Schmidt, an astrophysicist at the University of Nebraska-Lincoln, has identified 21 stars displaying similar mystifying behavior. Some of them exhibit more extreme dips in light than Tabby’s Star.
From NBC News:
“Schmidt identified 21 stars that showed possibly unusual dimming. These fell into two distinct categories: 15 were ‘slow dippers’ that dimmed at rates similar to Boyajian’s star, and six were ‘rapid dippers’ that showed even more extreme variability in their dimming rates.”
Schmidt will follow up on the data, especially for the “rapid dipper” stars:
“I intend to try and follow up on the rapid dippers,” Schmidt said. “One thing I noticed about them is that at least one seemed to be slowing way down in its dipping rate over the five years of coverage we have of it. It’d be interesting to find out what happened in its past, which may help give a better idea of what’s going on with these stars.”
So it looks like we’ll be finding out quite a bit more about these strange dimming stars in the near future. Will we find out more about ploonets, or about possible alien structures? Time will tell…
See more about Tabetha Boyajian and Tabby’s Star below:
Featured image: Tabby’s Star illustration via NASA / JPL-Caltech