In a region of space 650 lighty years
from us, there is a ticking time bomb.
When it detonates, it will unleash a
wave of fiery radiation and incendiary
matter careening across the Milky Way
galaxy, devastating objects in its path.
Planets that are too close will be
ripped to shreds, their stone turned to
magma, their atmosphere stripped away.
And this time bomb is near enough to us
that if we raise our eyes at night, we
can spot it unaded. It is one of the
brightest objects in the night sky. It
is Beetlejuice, our closest red super
giant, and it will soon go supernova.
But how soon is soon? Centuries, years,
days? And what will that mean for us on
Earth? In search of answers, scientists
have studied this volatile beer as it
teeters on the brink of annihilation,
seeking to unravel the processes and
signs that foretell its imminent
destruction. And as its timer ticks ever
closer to zero, we keep finding
ourselves being surprised.
I'm Alex Mccoan and you're watching Astramm. Join me today in this super cut
as we discuss everything there is to
know about Beetlejuice, including
incredible new discoveries that have
been made in recent years with one
little secret hidden in its shadow.
As always, let's start with some of the
basics. Beetlejuice is the 10th
brightest star in the sky, easily
visible as the left shoulder of Orion.
If you do look for it in the night sky,
it is also visibly redder than any of
the surrounding stars and it does a lot
of twinkling. Its color is expected for
its category. Beetlejuice is a red super
giant or a medium mass star.
Red super giants are far larger than our
sun and Beetlejuice is no exception. It
has a radius that extends beyond Mars's
orbit. Beetlejuice is almost 900 times
the radius of our sun, but maybe only 10
times more massive, meaning its density
is much lower. Its mass is spread out so
much that Beetlejuice's gravity is tiny.
It can barely keep itself from escaping
into space, which is why you see these
huge convection cells bubbling on its
surface in this computer model
simulation. Just imagine seeing a sunset
from a star like this.
But of course, the thing that you are
probably most interested in about
Beetlejuice is its impending demise.
Supernova in our galaxy are not that
common. While astronomers observe
hundreds of supernova every year outside
our galaxy, this is mostly a reflection
on how many galaxies there are in the
universe. Closer to home though, within
our own Milky Way, we likely only see
about two to three every century. This
means that the odds of one going off
tomorrow are not that high. But they're
not impossible. So, what might be the
impact of such a detonation? Of course,
it all comes down to proximity.
Interestingly, according to
archaeologists, the Earth has likely
been hit by a supernova before in the
course of its 4.5 billion years of
existence. For starters, we exist in an
area of space known as the local bubble.
A relatively sparssely populated region
of interstellar space about 1,000
lightyears across that is thought to
have been carved out by a supernova
detonation 10 to 20 million years ago,
which our planet would have been around
for. I talk about that in another of my
videos, which you can see here.
Scientists have found evidence of
another detonation that happened 2 1/2
million years ago due to a high
concentration of iron 60 and manganese
53 in a particular layer of the
geological record. This supernova have
been far enough away to be harmless to
us, but this might not always be the
case. There are some scientists who
believe that the extinction of woolly
mammoths was caused by a massive piece
of debris from a supernova crashing into
the planet about 13,000 years ago. The
impact site in question had magnetic
sphererals and radioactive potassium 40,
a substance found in supernova ejector.
A smoking gun in the era most mammoths
went extinct. Even before that, mammoth
tusks from 34,000 years ago were found
containing tiny impact craters from
grains of slightly radioactive iron that
have been traveling at 10,000 km/s.
Perhaps not coincidentally, that is one
of the potential speeds supernova
explosions travel at, namely between
10,000 and 40,000 km/s.
That can't have been a nice experience
for the mammoths in question. On that
try with a 14-day free trial. Now, back to the wider Earth's history.
An astute observer from this might be
able to note an important fact, however.
Evidently, if life began on Earth about
3.7 billion years ago and we faced three
supernova explosions that have impacted
us in the last 20 million years and life
is still largely ticking along, my
condolences, woolly mammoths, if you did
die out from one of these, then
supernova as a whole can't be quite as
destructive as my opening introduction
made them out to be. Well, not quite. As
I said, it is a question of proximity.
If I'm 1,000 km away from a nuke going
off, I have little to fear. But it's a
different story if one detonates on my
coffee table. And when it comes to
supernova, it turns out that the
universe has relatively large coffee
tables.
To understand the scale of these
explosions, it's necessary to understand
the forces involved. Which means we need
to understand a little better about how
supernova, like the one brewing inside
of Beetlejuice, happen. It turns out
that there's two main paths stars can
take to get to that explosive grand
finale. Although in each case, it has to
be the right kind of star. For the first
path, resulting in a type 1A supernova,
it usually needs to be a white dwarf in
a binary system that's gradually or
speedily siphoning matter away from its
neighboring star until it reaches a
point of critical mass. This path is not
fully understood, but it's thought that
a white dwarf or a dense star comprising
of mostly carbon in a giant super
diamond core is normally finally
balanced between two powerful opposing
forces, electron degeneracy pressure and
gravity.
This simply means that atoms usually
object to being squashed too much. Their
electrons like to remain at certain
distances from the nucleus of the atom
and will resist being pushed denser than
this point. But gravity is an incredibly
powerful force that seeks to draw matter
closer, particularly in a dense mass
like a white dwarf, where a section the
size of a sugar cube has the mass of
around a car. And in a binary system
where the white dwarf is absorbing more
and more matter from its neighboring
star, eventually gravity overwhelms
electron degeneracy pressure and the
whole house of cards collapses at once.
Carbon fusion begins. Within a few
seconds, most of the star underos
fusion, forming into heavier elements
and releasing a whole lot of energy as
the matter in the star settles into its
slightly more efficient new
configuration.
How much energy? Around 1 quarter roar
dicillion jewels. That's one followed by
45 zeros. If you claim you knew that
number before, you're almost certainly a
liar.
All of this energy is released in just a
few seconds. So naturally, the star
ejects its entire contents out in all
directions, sending it traveling at 6%
the speed of light and unleashing a
flood of mostly gamma radiation out
across the galaxy. The brightness of
this event is 5 billion times brighter
than our sun and burns for a few weeks
until the ejector has traveled far
enough that the overall energy level has
started to dissipate.
The second type of supernova, type two,
is similar, except instead of involving
a white dwarf, it involves a massive
star, at least five times more massive
than the sun at the end of its lifetime.
And this is the type much more relevant
to Beetlejuice. These stars are still
burning brightly. And rather than just
electron degeneracy pressure, it's also
the heat of fusion that keeps the star
in balance, converting hydrogen to
helium. This fusion creates an internal
pressure which combats the effects of
gravity, wanting to compress the star
into a smaller volume. However,
eventually the hydrogen fuel in the core
will run out, having been converted to
helium, meaning the fusion process stops
and the stars core can't overcome the
effects of gravity anymore. The core
compresses. But if the star is massive
enough, the compression will trigger
fusion again. This time with the helium
in the core into heavier elements like
carbon. With this process repeating for
oxygen and neon. With every new fusion
cycle, the stars internal pressure
expands the diameter of the star until
it begins the red super giant phase of
its life when the core is being
converted predominantly into iron.
However, just like a type 1A supernova,
eventually balance collapses. This time,
it's because the star runs out of fuel.
Red super giants can't fuse anything
beyond iron. So, beyond this, fusion
stops. And without this additional
fusion energy pushing the stars mass
outwards, electron degeneracy pressure
on its own can't cope with the stars
weight, giving a similar effect to what
we saw with a type 1A supernova. The
only difference is that while some of a
massive star will remain, often
collapsing down into a neutron star or a
black hole, white dwarfs usually vanish
completely.
Either way, the scale of material and
energy released by a supernova is vast.
So vast that unsurprisingly, anything
immediately next to it is not going to
last long. This is an energy powerful
enough to rip apart a star. A planet is
going to have no chance if it's in the
immediate vicinity. Our own sun
thankfully will never go supernova as
it's not massive enough. But if it did,
there is a good chance the Earth would
be either partially or completely
vaporized. Its rocky exterior reaching a
boiling point thanks to temperatures 15
times hotter than the surface of our sun
and being whisked away in the weeks of
the supernova's passing.
What is surprising, however, is how
quickly this first wave of devastation
would dissipate with distance. Indeed,
vaporization is realistically not the
largest threat supernova poses. In 2011,
experts from the University of Cambridge
calculated that even planets orbiting
their star at a distance of 15 billion
km, or about 100 times the distance
between the sun and the earth, would
remain intact and would instead simply
be sent flying out into space now that
there was nothing much left to orbit. Of
course, such a planet's hypothetical
ecosystem would probably have different
problems to worry about. Things would
get very cold very quickly.
Of course, even if the crust of a planet
itself remained intact, that doesn't
mean that life on said planet would be
sustainable. ignoring the light of a
supernova outperforming the brightness
of an entire galaxy sometimes leading to
blindness for anyone who saw it. Simply
stripping away our atmosphere would
carry problems. High levels of
radiation, even if it didn't affect us
directly, would alter the chemical
composition of our atmosphere. Negating
our ozone layer, vastly increasing our
odds of dying of radiation poisoning and
killing our phytolanton in the ocean and
causing mass extinctions. As the
consequences of that worked its way up
the food chain, scientists put this kill
zone to be within 25 light years. Beyond
that, the fury of a supernova begins to
calm as distance causes it to wear
itself out. Although admittedly, the
asteroid that potentially killed the
mammoths came from a supernova that was
250 lighty years away, if it happened at
all, it was likely bad luck. Generally
speaking, we wouldn't notice any damage
from a supernova this far away. Its
radiation levels wouldn't be high enough
to cause mass extinctions. By 500 light
years, we'd hardly notice the event at
all, other than perhaps seeing a
brighter star in the sky.
So, feel free to breathe a sigh of
relief. You are not in imminent threat
from Beetlejuice. Although,
incidentally, within 300 lighty years,
are there any other supernova
candidates? we need to worry about.
Thankfully, scientists are fairly
confident that the answer is no. Massive
stars are very noticeable, and the only
two that are at risk of going supernova
are Beetlejuice and Antares.
Both of those are more than 400 lighty
years away. White dwarfs are a little
trickier thanks to their diminished
brightness. They've been conventionally
hard to spot, making it harder to
predict whether we might be at risk from
them. However, in 2013, ISA's Gaia Space
Observatory released a massive packet of
information in its efforts to map the
stars that allowed scientists to
identify 13,000 white dwarf stars within
326 lighty years of us. Thankfully, in
spite of this large number, scientists
remain confident that none of these are
scheduled to explode anytime soon.
Soon meaning within the next few
hundred,000 years.
So, we are safe from a supernova for
now. And we can rest easy that when
Beetlejuice explodes, it will likely not
threaten the planet Earth. The shock
wave traveling out from Beetlejuice
would take some time to get to us. And
even once it arrived, it would be
traveling with less force than the push
of the solar wind. It wouldn't be our
magneettosphere or atmosphere that kept
us safe. The protective sheath of the
sun's heliosphere would be enough to
keep such a supernova at bay.
No harm will be flawless on Earth, but
it will make quite the spectacle.
Perhaps being as bright as a full moon,
so even visible during the day. Just
imagine that for a second. Seeing a
supernova shining in our sky will still
be a fascinating sight to witness. And
on top of that could reveal many secrets
about the murky process of supernova
explosions. So there's plenty of
interest in Beetlejuice. much of it
revolving around that singular question.
When will it go off? Beetlejuice will
detonate soon. Although I say that in
astronomical time scales. That means it
could take anything up to 100,000 years.
However, there are some scientists who
predict that this red super giant might
detonate within the next few decades.
Their research works under the
assumption that Beetlejuice has a much
larger radius than previously predicted.
And if it's true, it might mean that we
would get to see a local supernova
within our lifetimes.
But Beetlejuice does not give away its
secrets lightly. And over the last few
decades, it has thrown many curve balls
at us.
The inner workings of stars are
complicated and Beetlejuice dims and
brightens according to several not fully
understood cycles. It has a fundamental
rhythm that's likely related to its
eventual detonation and several that are
overtones, separate but connected. These
cycles can range anywhere between a few
hundred days to 2,170.
And there is some debate about which of
the cycles is its fundamental one and
which are its overtones.
As these are not fully understood, it
always seems like something interesting
is going on with Beetlejuice. It's been
in the news a lot, like in 2009 when it
contracted in size by 15%.
You may have also heard in 2019 that
Beetlejuice underwent a great dimming
and scientists didn't initially know
why. Speculations were running rampant
that this could be a precursor to the
promised supernova. Although perhaps
sadly, this is likely not the case. New
data from the Hubble Space Telescope
suggested that the star itself may not
really have been dimming, but rather
that some dust which was ejected by the
star may have cooled and obscured the
view. In September 2019, Hubble saw
heated material moving away from the
stars atmosphere. Over the course of the
next few months, this material was
observed near the star. By December, the
star began dimming in its southern
hemisphere. It is theorized that heated
carbon was in the outflow and as it
moved around the star, it expanded which
cooled it down. When we lost sight of
it, it didn't move away from the star,
but rather crossed over our view of
Beetlejuice. At its peak, Beetlejuice
was 2/3 dimmer than normal. However,
since April 2020, Beetlejuice has
actually returned to its normal
brightness. So this cloud has either
moved out of the way or totally
dispersed.
However, this event sparked renewed
interest in Beetlejuice. And with that
came an incredible discovery.
Beetlejuice frequently brightens and
dims in various cycles. But not all
instances of this are likely caused by
the star blowing off dust. At least one
cycle might instead be the work of a
tiny sibling.
For over a century, scientists had
wondered whether Beetlejuice might
actually be part of a binary system with
a little companion star caught up in its
gravitational pull. However, proving
such a thing was a tremendous challenge.
As Beetlejuice's surface was so unstable
and fluctuating, being able to track the
dimming and brightening that indicated
such a star's passing was almost
impossible.
However, after the great dimming of
2019, far more researchers started
turning their attention to Beetlejuice,
and two independent teams found evidence
that the longest cycle, the one running
every 2,170
days, could only be explained by
Beetlejuice having a neighbor. The key
to proving the existence of Beetle
Buddy, as it's colloally called,
although its official name is Siwara,
lay in looking back through radial and
positioning data. Researchers at the
Harvard Smithsonian Center for
Astrophysics in Cambridge,
Massachusetts, and another team from the
Center for Computational Astrophysics at
the Flatran Institute in New York both
looked at how Beetlejuice moved in the
sky and noticed a tiny repeated
variation over time, as if the star were
being pulled to one side and then the
other. This coincided with Beetlejuice
dimming, suggesting a star was causing
this effect. Both teams think that the
smaller beetle buddy is not much larger
than the mass of the sun and probably
orbits a little less than the distance
between our sun and Saturn.
Armed with this knowledge, other
scientists jumped into the fray. First,
they tried with space telescopes, but
were unsuccessful in finding a potential
companion star. So researchers at the
groundbased Gemini North telescope in
Hawaii turned the resolving power of its
8.1 diameter mirror in the direction of
Beetlejuice to try to spot its fertive
partner. Paired with a highresolution
camera called a speckle imager which
takes thousands of short exposure images
to compensate for interference from
Earth's obscuring flowing atmosphere.
They were able to look at Beetlejuice
when it was predicted this new star
would be at its furthest point from the
red super giant. And sure enough, they
found something. Although blurred, this
is thought to be an image of Siwara or
Beetle Buddy. So dim because its light
is six magnitudes fainter than its
volatile neighbor. This image is right
at the limits of Gemini's resolution
capabilities.
While it's not a 100% confirmation,
there are a number of other observations
and predictions that this sighting
appears to line up with, making it seem
very likely to be the star researchers
had been searching for. Though, we'll
have to wait until 2027 to double check
when it's next at its greatest
separation from Beetlejuice.
If this is true, it is a fascinating
aspect of this star's continued story.
It also helps us rule out the longest
cycle as being the fundamental mode, the
rhythm that dictates when exactly
Beetlejuice is going to go supernova.
Sadly for us, this makes it more likely
that Beetlejuice will take longer to
detonate. So perhaps it will not happen
within our lifetime at all. Of course,
while this is disappointing for us, it's
probably a relief for Beetle Buddy
itself, which will be well within
Beetlejuice's kill radius when it
finally does explode.
Predicting that moment though remains an
inexact art, at least partially because
much of what Beetlejuice seems to do is
very confusing. For example,
measurements from the Elmer array of
telescopes have detected that
Beetlejuice is rotating at a mindbending
rate of well, just about once every 20
years. Okay, that might sound a little
underwhelming, but for a star the size
of Beetlejuice, this means that the
surface is spinning at a speed of 18,000
km hour, or about 5 km/ second. That's
10 times faster than our own velocity on
the surface of Earth. And for a massive
super giant star, it all but breaks the
laws of physics.
How do we know this? Let's start with
the basics. There are a couple of
different ways to measure the rotation
of objects in the night sky. If the
object is big enough, like the sun, the
moon, or even a planet in our solar
system, it's easy enough to point a
telescope at it and watch its features
move in real time. For reference, the
angular diameter of the moon is about
half a degree, and you can probably make
out its features with your own eyes.
Jupiter's angular diameter comes in at
100th of a degree, but its features are
still clearly visible through a
telescope. So, what about Beetlejuice?
The super giant star just 650 light
years away. For all its size,
Beetlejuice is still far enough away
from Earth that its angular diameter is
1,000 times smaller than Jupiter's,
making it look like a total blur to even
our most powerful telescopes.
Luckily, there's another way to tell
whether a star like Beetlejuice is
rotating. It's less direct than just
well looking at it, but it's an
ingenious technique that relies on a
simple effect you might have already
heard of, Doppler shift. The same effect
is also responsible for the change in
pitch from a siren as an ambulance
passes by. When the ambulance is moving
towards you, the siren sounds higher
pitched because the sound waves hit you
at a higher frequency than if the
ambulance were standing still. But as
soon as the ambulance starts moving away
from you, the effect reverses. Sound
waves hit you at the lower frequency and
the siren sounds lower pitched. What you
probably wouldn't notice is that the
Doppler shift affects light waves
bouncing off the ambulance just like it
affects the sound waves coming from its
siren. The higher frequency light as the
ambulance approaches makes it look ever
so slightly bluer. And as soon as it
starts moving away from you, the effect
flips and it looks ever so slightly
redder. The only reason this visual
effect isn't obvious is because the
speed of light is a million times faster
than the speed of sound. So, it would
take a much faster ambulance for us to
actually notice the optical Doppler
shift.
We might not have ambulances here on
Earth flying by 5 km/s, but those kind
of speeds are fair game out in space.
Which brings us back to Beetlejuice.
When a star is rotating, half of its
surface will be moving towards us while
at the same time the other half will be
moving away. This creates a gradient of
colors emitted by the star that we can
observe with our telescopes. Even if the
star is too blurry for us to make out
any of its distinct features, by seeing
which side is bluer and which side is
redder, we can infer the direction of
rotation. And by measuring how different
the bluer frequencies are from the
redder ones, we can calculate the stars
rotational velocity. This was the
technique used by astronomers to analyze
the data collected by ALMA and conclude
that the surface of Beetlejuice was
spinning at 5 km/s.
That's all well and good except the
known physics of spinning stars predicts
that 5 km/s is far too large a velocity
for a red super giant like Beetlejuice.
Take our sun as an example. Its
rotational speed is in the same ballpark
around 2 km/s but is also 1,000 times
smaller and about 10 times lighter than
Beetlejuice. If our sun expanded to the
size of Beetlejuice, which would envelop
the entire inner solar system and nearly
reach Jupiter's orbit in the process,
then its velocity would drop to just 2
m/s
in order to conserve angular momentum.
In the same way that a spinning ice
skater slows down when she spreads out
her arms, and if the sun grew 10 times
heavier to match the mass of
Beetlejuice, its velocity would drop to
0.2 2 m/s.
So, the larger and heavier a star is,
the slower we expect it to spin. And
yet, Beetlejuice appears to defy all of
those expectations.
What's going on here?
One possible explanation is that even
though Beetlejuice didn't start out with
this much angular momentum, it gained it
through a process known as stellar
cannibalism. As you might expect,
stellar cannibalism is just what we call
it when one star eats another star,
usually its companion in a binary orbit.
In more scientific terms, the stars
gravity pulls away its companion's gas
layer by layer until only the inner core
remains. That gas carries most of the
companion stars angular momentum. So,
the first star ends up not only growing
larger, but also spinning faster than
nature would normally allow. But is this
really the story of how Beetlejuice got
its spin? Or is there something even
more mysterious happening under the
surface?
A team of researchers collaborating
across Europe and China have recently
suggested that Beetlejuice's apparently
ludicrous rotation speed might just be a
giant optical illusion.
To see how that's possible, let's think
back to what the team at ALMA really
measured with their state-of-the-art
array of telescopes. Though their
pictures of Beetlejuice were blurry,
they were still able to make out that
one half of the star emits slightly
redder frequencies of light than normal,
while the other half emits slightly
bluer frequencies. The obvious
explanation for this 50/50 split is that
the star is rotating with one half
moving towards us and the other half
moving away from us at the same time.
The green arrow in the image of
Beetlejuice is meant to represent the
axis of this rotation. But what if
that's not the only explanation for the
color gradient detected by Alma?
Simulations of Beetlejuice have revealed
that its surface is a chaotic, turbulent
place, constantly bubbling under its own
heat like water bubbling in an oven.
Each of these bubbles is enormous and
propagates outwards at deadly
velocities. A single bubble can be 100
million km across, covering a large
fraction of the surface of Beetlejuice.
And if one of these bubbles were headed
your way, even today's most powerful
spacecraft wouldn't save you from its
lightning fast speed of up to 30 km/s.
Your only hope would be for the bubble
to pop and crash violently back down
onto the surface before it ever reaches
you. As gas bubbles all over Beetlejuice
rise and fall, its surface becomes a
mosaic of regions that are either moving
towards us or away from us. as observers
on Earth. In turn, the Doppler shift
causes light emitted from these regions
to be either blue shifted or redshifted.
In a recent paper that rose to challenge
all previous explanations of
Beetlejuice's rotation, the
International team of researchers
proposed that Beetlejuice might not be
rotating fast at all. Instead, the Elma
observations might be detecting a range
of light frequencies coming from
Beetlejuice due to the turbulence on its
surface. Thus, astronomers may have been
misinterpreting those shifts in
frequency as rotational effect. But if
you've been paying close attention to
the physics, you might have noticed that
there's still a loose end with this
alternative explanation.
A rotating star should produce a smooth
gradient of light frequencies, ranging
from bluer than expected light on one
edge to redder than expected light on
the other. Meanwhile, a turbulent star
should produce a random patchwork of
colors with bluer patches where bubbles
happen to be rising and redder patches
where bubbles happen to be falling back
down. How could the astronomers at ALMA
possibly have mistaken one for the
other? If astronomers observed a smooth
gradient of colors coming from
Beetlejuice, shouldn't the patchwork
explanation already be ruled out?
In an ideal world, that would be true.
Gradients would correspond to rotation
and patches would correspond to bubbles.
But remember that Beetlejuice is so far
away that the image captured by Alma is
far from ideal. And it's more of a blur
than an HD photograph. When simulations
of the surface of Beetlejuice are made
to account for the limited resolution of
observations, they predict that the
bubbly patches of red shift and blue
shift will be easily mistaken for a
rotational gradient about 90% of the
time. This means that even if the
astronomers at ALMA did nothing wrong in
their analysis, they may have been
fooled by Beaselju's boiling surface
into thinking it's spinning way faster
than it actually is. This also means
that astronomers are now chasing after
one key objective. Higher resolution
studies of Beetlejuice that could more
accurately tell the two scenarios apart.
The good news is that better images of
Beetlejuice already exist, taken by the
same telescope, but with longer exposure
times. The bad news for those of us who
are more impatient is that it will
likely take a couple of years for them
to be properly analyzed. Those answers
are coming though. For now, I'm curious
to know where you would place your bets.
Is Beetlejuice really spinning at 5 km/s
after having eaten its companion star?
Or will the new claim that this rotation
speed is nothing more than an optical
illusion be vindicated?
So, there you have it. Everything you
might want to know about Beetlejuice, a
star on the brink of cataclysm. It is no
wonder we hold such a savage event with
such fascination.
Humans love explosions, as every
culture's love of seasonal fireworks
attests. So, whenever it comes, a
supernova detonation that lights up the
night sky will be awesome to behold.
Though, I'm glad that in Beetlejuice's
case, it will be from a very safe
distance.
richer for everyone. Now is the perfect
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