The state of our knowledge about the Universe is in a strange place now.
We can map countless stars around us, but we seem to be just stumbling upon every discovery.
Some of them are so puzzling, even skeptical scientists start to suspect aliens!
The brightest example is the Tabby Star, who’s light dims as if there was a giant artificial
megastructure around it.
But what’s really happening there?
KIC 8462852, or simply called Tabby Star, is a mysterious celestial object situated
in the constellation Cygnus, some 1,470 light-years away from the Sun.
Nothing about this star is particularly exceptional.
It’s about 50% bigger than our Sun, and 1,000 degrees hotter, and there are other
objects just like it in the Universe.
Nevertheless, it became known as the strangest star ever observed.
To understand why, we should dive a bit deeper into how it was first found.
Astronomers have developed several methods of detecting and researching stars throughout
the recent decades of rapid technological progress, but one of them stood out.
It wasn’t only suitable for star discovery, but also allowed the detection of some of
our greatest points of interest to date.
Exoplanets.
Outer worlds, orbiting distant stars.
They’re hiding the keys to all the mysteries about our solar system, and any possible answers
to the sacred questions we’re still afraid to ask: how did we come to be, and is there
any other life in the Universe?
This method is called transit photometry.
Don’t mind the big name; to simplify it to its core, this method can be explained
with a trivial example.
Imagine you’re looking at some distant light, and then something flies right in front of
it.
The light is too bright and the object is too far and fast for you to even guess if
it was a bird or a bat, but you can tell for sure that something was there a second before.
That’s because the light itself dimmed and flickered for a moment.
You can even figure out how big that object that passed by was, by how long and strong
the observed dimming was.
Transit photometry measures the dimming of the star’s light when the planet passes
on its orbit between the point of observation and the star in question.
As you can already see, this method provides a lot of information, but has its flaws.
This is exactly the reason why so much guesswork is involved when using transit photometry.
Despite that though, a record number of exoplanets were discovered using it in 2014 – around
850 planets total!
Tabby Star is named after Professor Tabetha Boyajian, who was the first to notice a strange
quality: while other stars dim by about 1% when a planet passes in front of them, Tabby
Star dimmed much more.
The first recorded sightings of it, made in 1890, testify that by the year 1989, this
star had lost about 20% of its shine.
Of course, this couldn’t be caused by a planet passing by.
Let’s just say it would take a planet bigger than the star itself to do that, but that’s
just impossible.
Stars remain the same brightness for billions of years with almost no change at all.
It became even more strange when astronomers figured out that Tabby Star is in the middle
of its life-cycle.
There shouldn’t be any disturbances in its light whatsoever.
But what caused the dim then?
This is where the notorious guesswork began.
Or should I say, a long scientific investigation.
In 2016, Boyajian and her team found archive recordings suggesting that Tabby Star isn’t
just fading rapidly.
At times, its shine is restored to its natural state, and then it gets obscured once again.
They were even able to figure out a pattern of dims, reliably predicting the next shift
in brightness.
This produced the first theory – Tabby Star may have a giant hive of comets and asteroids
orbiting around it.
It could obscure the light of the star in the places where the group of objects is denser.
But that theory fell short.
Hives like that are observed only around young stars going through the process of their formation,
and Tabby is much older than that.
Besides, a high number of comets around the star would produce a titanic amount of infrared
radiation, but it wasn’t ever detected.
And then consider the following: the shifts of brightness are identical each time; some
of them even go in a symmetrical shape.
Can you imagine a hive of comets that goes in a strict order with each spin around the
blazing star?
That’s unheard of; they would change their position constantly.
Their movement would appear almost chaotic to any observer on the Earth.
Looks like lots of comets, but goes in strict patterns?
Yeah, you’re not the only one who thought that it sounds like something unnatural.
In fact, the idea of a structure spinning around a star is long known to astronomers.
It’s called the Dyson Sphere.
Hypothetically, a structure like this could be made by a highly developed civilization
to harvest the energy from a star.
It would consist of a high number of thin plates positioned around a star – you can
imagine them like moon-sized solar panels.
The most interesting thing about this idea is that such structures would be relatively
easy to find, because they would obscure the stars in a strange and inexplicable way.
Dyson Spheres are proposed to be the first sign of a highly advanced civilization existing
in the Universe.
The probability of a Dyson Sphere causing Tabby Star’s dimming was put to the test
by searching for any radio signals in the area of the star, but unfortunately, scientists
were met with nothing but silence.
There’s a catch though.
Our data can be unreliable if we’re really talking about some other civilization.
If they’re able to build something like the Dyson sphere, they might not use radio
signals at all.
It’s unimaginable for us here and now, but in a somewhat distant future, we too may refuse
to use the radio as a prime way of communication.
Just some 300 years ago, we could only use the postal service to communicate with each
other from a distance.
On a galactic scale, 300 years is just the blink of an eye!
Imagine how wondrous some new or completely alien technology could be!
Anyways, the scientific community was, shall we say, outraged about the decision to even
try and test the alien theory of Tabby Star’s mystery in the first place.
From a skeptic’s point of view, it’s always better to rule out every other natural possibility,
and only then consider something un-natural like that.
So recently, another, much more grounded, Tabby Star theory emerged.
According to it, there must be a giant brown dwarf planet going around Tabby Star at distant
orbits.
And I mean giant.
Brown dwarfs are barely considered planets at all.
They are objects much more massive than the biggest of Jupiter-like planets, but smaller
than the tiniest red dwarf star – the lightest type of star there is.
The presence of several brown dwarfs in orbit around one star is quite unlikely by itself,
but that’s not even everything that would have to be involved to result in something
like the mysterious Tabby Star dimming.
These brown dwarfs should have colossal asteroid rings.
And once again, I can’t stress the word ‘colossal’ enough – these rings should
be far beyond the limit that we’re aware of currently.
This limit has a name – Roche radius.
Beyond this radius, no asteroid ring can sustain its form; it’ll eventually all collect into
one object and become a satellite.
The particular brown dwarf that’s theoretically orbiting Tabby Star would have to be 15 times
more massive than Jupiter, and have 6 layers of planetary rings.
It still doesn’t sound too reliable, but that’s the best theory there is.
Or, to be fair, the best there was until last year.
Astronomer Brian Metzger and his colleagues at Columbia University suggested that the
objects surrounding Tabby Star and causing the strange flickering of its light might
be the remains of crushed planets and their exomoons.
Their theory implies that those planets could’ve crossed the same old Roche radius of the star
itself.
When that happens, the planets would deform, pull, and flatten; then they break into pieces
under the colossal influence of Tabby Star’s gravitational force.
Even though this should’ve happened around 200,000 years ago with Tabby Star and its
planet, the remains of this object would still be in a close orbit of the star.
That’s what obscures Tabby Star from our telescopes from time to time.
Can this theory place a period in the long investigation of Tabby Star’s mystery?
It’ll eventually be proven either true or false.
Until then, Tabby Star will remain the greatest secret of the stars.
Now, have you heard of some strange celestial objects or phenomenon that caught your attention
more than this one?
Let me know down in the comments!
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