It’s said that nothing lasts forever, not even celestial wonders of the universe like
the great Betelgeuse.
The supergiant star is at the end of its life, and in 2019 Hubble noticed it doing something
weird…
Something that had never been seen before.
Welcome to Factnomenal and in today’s video we take a close look at what the Hubble Space
Telescope revealed about the 10th brightest star in our night sky - Betelgeuse.
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Betelgeuse, Betelgeuse, Betelgeuse…
Approximately 548 light years away from Earth
lies the second-brightest star in the constellation
Orion - Betelgeuse.
No, not the self-described "Ghost with the Most", but just as intriguing!
Also known as Alpha Orionis, Betelgeuse marks the eastern shoulder of The Hunter.
The infamous red supergiant star gets its name from the Arabic term ‘yad-Al-jawza’
which literally translates to “the hand of the central one”, the “central one”
being Orion.
The variable star is so luminous that it can be seen with the naked eye - if… you know
just where to look, that is.
The star is estimated to be around 10 million years old, which is already quite old for
a supergiant, and it’s nearing the end of its life.
Now, if you compare it to the Sun, Betelgeuse is said to be around 13,000 times its luminosity!
So, if you ever catch yourself complaining that the Sun is too bright, well, just be
grateful our planet doesn’t revolve around this bright monstrous star.
So, what’s all the chatter about the big ol’ bright star with the crazy name?
As stars get older, they tend to burn out their supply of hydrogen fuel quickly before
switching to helium and other elements.
This continues into the expanding and cooling stage, until the fusion of heavier atoms takes
place - at which point the giant star completely runs out of fuel, and its iron core reaches
critical mass.
If the star is as big as Betelgeuse, the entire star then collapses and explodes, or in other
words “goes supernova”.
Because of how far Betelgeuse is from Earth, it is quite possible that Betelgeuse has even
gone supernova already, but the light from it will not reach the Earth for another few
centuries.
When that day does come, it will be a truly spectacular sight that would likely be visible
even during the day for months and months on end.
Just imagine looking up into the night sky and seeing the entire spectacle with your
own eyes, without the aid of a telescope!
To top it off, radiation from the explosion is unlikely to hit planet Earth - which is
spectacular news for the future of mankind, even if we won’t necessarily be around to
actually see any of it.
The Great Dimming Mystery
In late 2019, astronomers around the world were buzzing because for the first time ever,
Betelgeuse grew fainter and fainter than it had ever been before.
This is not an odd phenomenon in and of itself, but the supergiant star being at the end of
its life makes it, therefore, a very interesting subject, and could offer insight into the
death of a supergiant star like never before.
To make things more interesting, by February 2020, the star had already lost about two
thirds of its normal luminosity as seen from Earth.
The dimming persisted, decreasing in brightness by 35 percent in mid-February, before brightening
up again in April 2020.
There were various theories being thrown around about this “great dimming” of Betelgeuse,
with some scientists suggesting the star could be going supernova.
Others were convinced that a giant dust cloud was in fact obscuring the light from the star
- which also seemed quite possible.
The buzz went on for a while and all telescopes were pointed at Betelgeuse, until scientists
made a shocking discovery...
Using the Hubble Space Telescope, they were able to reveal that there was, in fact, a
giant dust cloud to be blamed.
But it was not quite what they had predicted.
A plume of more than 1 million miles (1.6 million kilometers) across, may have arisen
from the star's surface.
This gigantic plume seems to have caused a sort of star quake, a shock that blew out
an entire chunk of the star's surface, equivalent to 400 million times greater than the stuff
that is usually seen from our Sun's Coronal mass ejections (CME).
The Sun of our solar system routinely ejects mass, which is commonly referred to as solar
flares.
But the Sun only blows off small pieces of its outermost layer, known as the corona - hence
the term coronal mass ejections.
But with Betelgeuse it seems to be completely blowing its top off!
The event is called surface mass ejections (SME) and is not likely the same as coronal
mass ejections.
Hubble's Discovery
An international team of astronomers, who happened to have the Hubble Space Telescope
pointed at Betelgeuse before, during, and after the entire dimming event, combined their
observational data to show that a cloud of dust near the star may have caused the star
to appear darker.
Their findings suggested that the outer layer of the star, called the photosphere, had begun
to accelerate outwards, before the star began to dim.
Andrea Dupree, leading the study, and her colleagues, suggested that as the star expanded
in one of its usual cycles, a portion of the surface accelerated more rapidly, due to something
called a “convection cell” that had travelled from the interior of the star up to its surface.
The combination of the events happening at the same time pushed out sufficient material
from the star - forming stardust.
It is this very dust that is the main culprit for the dimming that was then seen here from
the Earth.
Images were captured by the European Southern Observatory’s Very Large Telescope (VLT)
where you could actually see the appearance of the star changing in real time on a scale
of weeks.
The images, along with earlier observations from 2019 and early 2020, gave the astronomers
a chance to witness the stardust formation in real time - a gorgeous and groundbreaking
occurrence - unlike anything ever seen before.
The ESO team additionally concluded that a gas bubble was ejected and pushed further
out by the outward pulsation of the star.
Furthermore, when the convection-driven cold
patch appeared on the surface, the local temperature
decrease was more than sufficient to condense heavier elements like silicon into solid dust,
thus forming a dusty veil that would then obscure the star's brightness - particularly
in the Southern Hemisphere.
A paper was published regarding the same in the Astrophysical journal, with the study
author, Andrea Dupree, stating:
“Betelgeuse continues doing some very unusual things right now.
The interior is sort of… bouncing”.
This is extremely new and uncharted territory when it comes to star science.
Dupree further explains:
"We've never before seen a huge mass ejection of the surface of a star.
We are left with something going on that we don't completely understand.
It's a totally new phenomenon that we can observe directly, and resolve surface details
with Hubble.
We're watching stellar evolution in real time."
The Aftermath
Solving the great mystery surrounding the dimming of Betelgeuse has brought a lot of
clarity, and opened new possibilities for the supergiant star.
The new observations have yielded some exciting clues as to how red giants lose their mass
later in their lives, as they slowly burn
all their reserves, before exploding as supernovae.
Scientists have now dubbed the event ‘stellar evolution’ in real time.
A star as big as Betelgeuse blowing off huge chunks of its own surface mass is definitely
not a common phenomenon, and to be able to witness this as it happens is a once in a
lifetime opportunity.
But if you think this is finally the end for this cosmic wonder... guess again.
Researchers have stated that though there has been an unusually large amount of ejection,
that doesn’t necessarily signal an imminent explosion.
It simply tells us how little we really understand these supergiant stars, and it is certainly
a phenomenon that will require a lot more study and understanding.
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So, what do you think?
Will Betelgeuse go supernova anytime soon?
Could the James Webb Space Telescope help us locate other rare space phenomena?
Let us know in the comments!
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miss a thing!
Thanks for watching, we’ll see you next time!