[Music]
stars are some of the most beautiful and
or inspiring objects in the universe
through violent thermonuclear reactions
they emit enormous amounts of light
Illuminating the night sky and heating
up any nearby planets in the process
through merges and Powerful explosions
stars are also responsible for producing
the heavy elements that make up much of
the m we see around us astronomers and
astrophysicists have come a long way
toward understanding how Stars operate
to the point where we can even predict
how long it will be before our sun runs
out of fuel and transforms into a red
giant but today we're not just going to
talk about the types of stars we're
familiar with instead we're going to
contemplate Stars we've never seen
before ones that astrophysicists say
could hypothetically exist
including ones that are quite literally
made of
vacuum I'm Alex molan and you're
watching astram join me today as we dive
into the world of exotic Stars some of
these Stars can mimic black holes and
resemble dark energy which is why they
have been the subject of many recent
studies and even some Sensational drama
in the world of physics in this video
we're going to explore all of it from
the physical theories is at the core of
these ideas to the wildest speculations
surrounding
them first we need to lay some
groundwork and understand how Stars work
in general starting with the most
important star of all the sun since the
sun is made of gas or plasma and not
solid matter you couldn't stand on its
surface like you would on the earth the
Sun's gravity would pull you down toward
the center so why doesn't the gas of the
surface get pulled inwards
too it turns out that there is a
pressure pushing outward from the sun's
core that counterbalances this pull of
gravity the main source of this pressure
is the radiation created by Fusion
reactions in the core the same radiation
responsible for carrying light and heat
from the Sun to the
Earth whether you think of radiation as
individual photons or waves in the
electromagnetic field it's path from the
core towards the outer layers of the sun
will cause an outward push in all
directions this radiation pressure
wouldn't be enough to stop you from
falling into the Sun but it's just
enough to stop the sun's own gas which
is relatively light from collapsing in
on
itself this Balancing Act between inward
pulling gravity and outward pushing
pressure is a feature of pretty much all
known types of stars what differentiates
different different types of stars is
where that pressure comes from for our
sun the pressure comes from fusing
hydrogen into helium when the sun runs
out of hydrogen in about 5 billion years
it will become a red giant star and
begin to generate its pressure by fusing
helium into even heavier nuclei like
carbon and
oxygen eventually the sun will also run
out of helium and any other light
elements that could be used for fuel for
nuclear
fusion at that point it will collapse
into a small star known as a white
dwarf since no more Fusion is occurring
anymore white dwarves are sometimes
called Stellar remnants instead of
stars but if there's no more Fusion
where does the pressure to support these
Stellar remnants come from it turns out
that gravity pulls the gas of a white
dwarf inward until it's so dense that a
new type of pressure emerges known as
electron degeneracy pressure this is a
purely quantum mechanical effect and
it's the same effect that's responsible
for you not being able to pass your hand
through solid objects electrons simply
cannot get too close to each other
without an extraordinary amount of
energy but some Stellar remnants are so
massive that even electron degeneracy
pressure isn't strong enough to
counteract the pole of gravity this is
called the Shandra sea limit
it's absolutely impossible to have a
stable white dwarf any heavier than 1.4
times the mass of the Sun if a star has
burned through all its nuclear Fuel and
its core is still heavier than the
Chandra car limit that core will
collapse in on itself until it becomes
so dense that an even stronger type of
quantum pressure emerges known as
Neutron degeneracy pressure which as you
may have guessed prevents neutrons from
getting too close to each other a star
that reaches this state is called a
neutron star the smallest and densest
known class of Stellar
objects so now you might be wondering is
there a maximum mass that a neutron star
can have while still being supported by
Neutron degeneracy pressure and there is
this time it's about 2.2 time the mass
of the Sun any heavier than that and the
neutron star would keep collapsing under
the influence of its own gravity until
well actually not until anything as far
as we know Neutron degeneracy pressure
is the strongest possible pressure that
ordinary matter can exert so there's
nothing left to prevent a sufficiently
heavy Stellar Remnant from collapsing in
on itself
Forever This is the Fate that might
await some of the most massive stars
we've observed in the
universe from the perspective of an
outside Observer these Stars would get
so dense that all we'd be able to see is
a black
hole but then scientists started to
wonder what would happen to a star that
wasn't made of ordinary
matter if exotic forms of matter could
hypothetically produce even larger
pressures than Neutron degeneracy
pressure then what new kinds of stars
could
exist you might think that we could just
continue the pattern that we were
starting to see earlier Stars could get
even smaller and even denser than
neutron stars as long as they were
supported by some even greater pressure
you might think that the only limit on
how small these Stars would get would be
the point of no return where they would
turn into black holes that point of no
return is when a star becomes smaller
than in its own schat Shield
radius this is almost true but not quite
instead physicist Hans Adolf Bal showed
in 1959 that a star made of any
realistic form of matter with positive
energy density and pressure can't be
smaller than 9/8 times its fart Shield
radius it might not sound like a big
difference but that factor of 9/8 means
that any realistic star has has to be
noticeably larger than a black hole
making it much easier to tell them
apart that's when physicists began
asking about stars that bdal would call
less
realistic for example what if a star was
made of matter that allows for pressure
to be negative in some regions and
positive in others then bal's limit
wouldn't apply and that star would be
less than 9/8 times its fat Shield
radius in fact it could be arbitrarily
close to the size of a black hole with
the same mass as a side note theoretical
stars like these that could mimic the
appearance of black holes came to be
quite a nuisance for astrophysicists
since now every time they discovered
something that they thought was a black
hole they couldn't just say they
discovered a black hole they had to
qualify that it's either a black hole or
an extremely compact object mimicking a
black hole even though in their heart
most of them are quite convinced that
it's a black hole but back to the main
point what would these exotic stars with
negative pressures even look like the
answer turns out to be even weirder than
you might have guessed Tolman
Oppenheimer and vulkov derived an
equation in the 1930s that describes how
the pressure of a stable star changes as
you go outward from its Center these
days it's just called the Tov equation
for short if the center of a star has a
significantly negative pressure which
would exert some sort of attractive pull
instead of a push the T equation says
that this star can only be stable and in
balance with its own gravity if its
pressure does something really
wonky first the pressure has to blow up
to negative Infinity somewhere in the
star then it has to flip sign to
positive infinity and decrease outwards
from there until it reaches zero
pressure marking the Stars outter
surface the exact location of the
infinite pressure depends on what the
pressure is at the center so if you tune
that Central pressure just right you can
keep the pressure finite right up until
the edge of the star that happens when
the pressure at the center is exactly
equal and opposite to the star's energy
density there
in this special case the top equations
say that the pressure and energy density
remain constant equal and opposite
throughout the entire volume of the Star
right up until its surface if you've
seen some of our other episodes this
might ring a bell or two a constant
positive energy density paired with a
constant but negative pressure that
doesn't sound like any Star we've seen
before but it's starting to sound more
like a mysterious component of our
universe dark
energy and since the pressure and energy
density in a gravistar are equal in
magnitude it's not just any kind of dark
energy those are the exact properties of
vacuum energy that's why this special
exotic star came to be known as a
gravitational vacuum star or gravar for
short in ins side of a gravistar there
is precisely zero gravitational force
because the positive energy and negative
pressure respectively exert a
gravitational pull and push that cancel
each other out and since the pressure in
grav stars is constant there is no
pressure gradient to exert any sort of
push in One Direction or another either
this means that if you found yourself
inside of a gravistar you would neither
be pulled in nor pushed out you could
float freely just as though you were in
a real
vacuum another curious feature of stars
with negative pressures is that The
Closer you get to the special limit of a
gravar which if you recall is when the
infinite pressure surface gets pushed
out to the edge of the star the more
their size approaches that of a black
hole with the same mass this raises two
key questions that have recently gotten
a lot of attention from physicists
first how can we tell whether the
extremely compact objects astronomers
have observed in merger events and at
the center of large galaxies are black
holes or just exotic stars with nearly
the same
size and second if grav stars are real
and Scattered throughout the entire
universe that could they be the dark
energy that's been making the universe
accelerate for the past 5 billion years
years to answer the first question
physicist rely on the main distinction
between black holes and other compact
objects the existence of an event
horizon you see the defining feature of
a black hole is that nothing that falls
inside or even touches the surface of a
black hole can ever come back out on the
other hand if an exotic star is even
slightly larger than its sh Shield
radius it would not have an event
horizon and it would potentially be able
to emit information out outwards in the
form of light not only that but objects
without event Horizons could have
different signatures in their
gravitational wave emissions than those
of black holes during a merger this
would allow us to tell them apart by
measuring and analyzing those
gravitational waves using observatories
like ligo but even with this battery of
tests it turns out sufficiently small
and dense Stars can still be difficult
to distinguish from black holes so far
the best we can do is to say that the
radius of the black hole candidates we
see in the universe is at least
approximately equal to the schwat shield
radius in some cases that's just a rough
estimate but in others we've calculated
that radius to within 40 decimal places
as for the second question about dark
energy that's where things get really
heated in early 20123 an analysis led by
physicists at the University of Hawaii
found that astronomic observations of
massive black holes showed them to be
growing in Mass over time at exactly the
same rate the dark energy would be
expected to grow over time due to the
expansion of the
universe they came to the inevitable
conclusion that black holes must be made
of dark energy and that they are really
more like grav Stars than ordinary black
holes with infinite density
singularities at their
centers this conclusion was fiercely
tested astronomers came out arguing that
the analysis of the observational data
wasn't quite right and theoretical
physicist came out arguing that the
expansion of the universe should have
nothing to do with the growth of black
holes in any case so while the idea that
dark energy could exist in the form of
GRA Stars sounds exciting it looks like
the scientific Community isn't going to
be convinced unless it's simultaneously
supported by better data and more
compelling theoretical models
but where do you fall in this debate if
it walks like a black hole and talks
like a black hole should we just call it
a black hole or should we consider the
possibility that black holes could
really be secret troves of dark energy
let us know your thoughts and questions
in the comments
below if you're a longtime viewer of
astram you'll already know that
Beetlejuice is no ordinary star beetle
juu is a red super giant in the Orion
constellation that's just 650 light
years away from the solar system making
it the second largest and 10th brightest
star in the sky not counting the Sun a
few years ago Beetlejuice made headlines
when the bright super giant appeared to
be getting dimmer indicating that it
might be about to explode in a
supernova but that wasn't the only
surprise that Beetlejuice had in store
for astronomers measure ments from the
Elmer array of telescopes have detected
that Beetle Juice 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 Beetle Juice this means that the
surface is spinning at a speed of
18,000 kmph or about 5 km/ Second that's
10 times faster than our own velocity on
the the surface of Earth and for a
massive super giant star it all but
breaks the laws of
physics I'm Alex molan and you're
watching astram join me today as we dig
into the unusual surface of beel juice
and the secrets behind its seemingly
impossible rotational
speed 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 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 Beetle
Juice 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 beetle juu
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 side and
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 at 5 km/s but those
kind of speeds are fair game out in
space which brings us back to Beetle
juu 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 beetel juice was spinning at
5
km/s that's all well and good except the
known physics of spinning Stars predicts
that 5 km per second is far too large a
velocity for a red super giant like
Beetle juu take aan as an example its
rotational speed is in the same ballpark
around 2 km/s but it's also 1 a thousand
times smaller and about 10 times lighter
than Beetle juu if our sun expanded to
the size of beetle juu 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/ second 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
Beetle Juice its velocity would drop to
0.2
m/s so the larger and heavier a star is
the slower we expect it to spin and yet
Beetle Juice appears to defy all of
those
expectations what's going on
here one possible explanation is that
even though Beetle Juice didn't start
out with this much angular momentum it
gained it through a process known know
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
star's gravity pulls away its companions
gas layer by layer until only the inner
core remains that gas carries most of
the companion star's 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 Beetle juu 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 Alma
really measured with their
state-of-the-art array of
telescopes though their pictures of
Beetle Juice 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
Beetle Juice 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
Beetle Juice 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 beetle juu and if one of these
bubbles were headed your way even
today's most powerful spacecraft
wouldn't save you from its lightly fast
speed of up to 30 km per second 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 doer shift causes light
emitted from these regions to be either
blue shifted or red shifted in a recent
paper that Rose to challenge all
previous explanations of beetlejuice's
rotation the international team of
researchers proposed that Beetle juu
might not be rotating fast at all
instead the Elma observations might be
detecting a range of light frequency
coming from Beetle juu 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
this 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 Beetle
Juice 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 Beetle Juice 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 Beetle Juice 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 beel Juice'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 Beetle Juice that could more
accurately tell the two scenarios apart
the good news is that are better images
of Beetle Juice 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 Beetle juu really spinning
at 5 km per second after having eaten
its companion star or will the new claim
that this rotation speed speed is
nothing more than an optical illusion be
Vindicated let me know your thoughts in
the comments
Below have you ever wished you could see
a supernova up close while we don't
quite expect that in 2024 you will have
a chance to see what is arguably the
next best thing namely the explosion of
the blaze star and surprisingly it just
keeps
exploding back in May 8 1966 on a partly
cloudy spring night in the west of
Ireland amateur astronomer John
Birmingham was on his way home in the
dark just before midnight his Pace
slowed occasionally so that he could
look up at the stars with a sharp eye he
scanned the night sky for familiar
constellations like he had done
countless times before as his eyes
reached the northern Crown he stopped
stunned there was a new bright star in
this familiar
constellation he had observed a
recurring Nova in the binary star T cron
Borealis nicknamed The Blaze star an
explosive astronomical event that
happens once in a lifetime this event
would help to revolutionize our
understanding of Nova events and shape
the field of Stellar astronomy in the
following decades and for those of us
alive in 2024 we will have the unique
opportunity to experience the same
recurring no explosion that captured
birmingham's Fascination more than 150
years ago on that Cool Spring night in
Ireland and you won't even need a
telescope or any fancy equipment to see
it why is it going to happen again and
when will it happen I'm Alex molan and
you're watching astrom join me as we
prepare to observe this extraordinary
Stellar
event the nickname Blaze star may be a
bit misleading as it's actually a binary
system of two stars locked in orbit with
each other and it's the relationship
between these two stars that causes the
Nova explosion to occur every 80 years
or so in fact it's estimated that about
50% of the Stars we see are not solitary
but multiple star systems both of the
stars in the binary Blaze star system
started out as average size Stars
similar to our sun but each one is at a
very different state in their life
cycle small and midsize Stars generally
follow the same evolutionary path as our
own Sun at 4.6 billion years old our sun
is considered a middle-aged average
sized star in 5 billion years it will
run out of hydrogen fuel and begin to
fuse heavier elements expanding into a
red giant that may become so large that
it engulfs Mercury Venus and possibly
even Earth as the red giant uses up its
remaining fuel sometime between 5 to 10
billion years from now it will
eventually cast off its outer shell
creating a nebula of gases surrounding a
white dwarf the extremely dense and
small core remnants of the once Giant
star white dwarfs are often called dead
stars as they have no more fuel and will
spend the next 10 trillion years cooling
off until they no longer emit heat or
light both of the binary stars in The
Blaze star system are average size stars
on the same trajectory but they are
further along in their Stellar Evolution
than our sun in fact this is the very
reason for the recurring Nova we will be
able to witness in 2024 it all comes
down to the relationship between these
two stars one a red giant and the other
a white dwarf as the red giant heats up
and its outer shell expands it is
continually stripped of hydrogen by the
immense gravitational pull of its
neighboring white dwarf over time the
white dwarf collects this material on
its surface kind of like a cosmic vacuum
cleaner causing a buildup of pressure
and heat eventually this buildup becomes
too much and causes a thermonuclear
explosion that blasts away all of that
builtup material picture the white dwarf
like a party popper you keep pulling the
string Tighter and Tighter adding
tension finally you pull too hard and it
pops sending confetti flying everywhere
this is kind of like the pressure and
heat that builds up on the blaz star's
white dwarf until it finally reaches its
limit the result a Nova explosion so
powerful it can make the blazar appear
1, 1500 times brighter than usual about
once every 80 years as seen from Earth
3,000 light years
away so how is this different from the
more famous supernovas while the blaz
star does experience a massive explosion
with each Nova referred to as a classic
Nova it does not destroy the white dwarf
where it occurs instead it simply blasts
away the material collected from its
neighboring star every now and then when
pressure and heat become too much and it
happens to be close enough to us that we
will experience a significant change in
its brightness from
Earth on the other hand for a solit star
to destroy itself at the end of its life
by exploding in a grandio supernova that
can be millions of times brighter than
the blaze Nova it has to start out with
more than eight times the mass of our
sun much more massive than those in the
blaze star the closest star on a path
toward a supernova explosion in the near
future is the red super Giant Beetle juu
a star that often appears as one of the
10 brightest in our night sky despite
being 640 light years away and by the
near future I mean in Cosmic perspective
so don't worry scientists don't expect
this star to go supernova for tens of
thousands of years in Cosmic terms
that's just around the corner in human
terms not so much but just for a moment
imagine the awe inspiring view that
anyone on Earth would witness as Beetle
Juice explodes in a supernova after the
initial explosion the star would become
as bright as a full moon and remained
visible during the day what a sight that
would
be however while extraordinarily rare
Beetlejuice won't be the first time
humanity has witnessed a supernova and
the blaz star is certainly not the only
Nova in recent history to be visible to
the naked
eye the oldest record of a supernova now
called sn1 185 comes from Chinese
astronomers in 185 ad when they recorded
what was called a GU star which appeared
in the night sky for a staggering 8
months modern astronomers have been able
to find the remnants of this explosion
to confirm that it was in fact a
supernova there have only been a handful
of supernova that were visible with the
naked eye in recorded history one of the
famous instances and most recent was in
16004 when the German astronomer
Johannes Kepler documented a supernova
that was so bright people could see it
during the daytime
what we will experience in 2024 is
expected to be one of the brightest
classic Nova of this century and just
like a supernova this is a rare and
noteworthy occurrence classic novas that
are visible to the naked eye occur
relatively frequently at least compared
to Super no but despite these classic
Nova being visible in our night sky
about once every year or two they are
rarely bright enough for the untrained
or unaided eye to spot The Blaze star on
the other hand is expected to be one of
the brightest classic Nova to appear in
our night sky in nearly 50
years in astronomy a star's brightness
as seen from Earth can be measured on a
scale of apparent magnitude the smaller
the magnitude the brighter the star so a
star with a magnitude of zero is
brighter than a star with a magnitude of
one star with a magnitude of one is
brighter than a star with a magnitude of
two and so on typically it takes an
apparent magnitude of about 6.5 in order
for a star or planet to be visible to
the naked eye on the darkest night for
some perspective the Seven Stars in the
öa Major constellation also known as the
Big Dipper have apparent magnitudes
ranging from the Diest at 4.8 to the
brightest at a magnitude of
1.7 the brightest star in the night sky
is serious with a magnitude of -
1.44 and the daytime sze
has a magnitude of -
26.5 yes the apparent magnitude scale
goes into the negatives the magnitude of
the blaze star is usually 10 and not
visible to the naked eye from Earth but
during the Nova explosion every 80 years
this star Peaks at a magnitude between 3
and 2 making it appear from seemingly
nowhere to become one of the brightest
stars in the sky interestingly the term
NOA comes from a Latin word meaning new
and I'm sure that before telescopes it
must have been a shock to see a new star
appear out of
nowhere more recently there was Nova
centor
2013 which surprised astronomers by
being one of the brightest in over a
century with a peak magnitude of
3.3 the last time the blaze star no
exploded in
1946 it reached a magnitude of
three but this Year's appearance of the
blaz star is expected to be even
brighter than that possibly reaching a
peak magnitude of two which would rival
that of Polaris the North Star which has
a magnitude of
1.97 but this Stell show won't last long
once it erupts with an no explosion The
Blaze star may only be visible to the
naked eye for a few days or a week
before it fades back into the darkness
there is no exact date when it will
happen but scientists predict it may
happen any day now going into the second
half of 2024 be sure to keep an eye on
the news and the sky to find out when
the NOA explosion begins to find the
blaze star in the night sky look for the
two neighboring constellations of
Hercules and the kite shaped botes The
Blaze star will be located in a small
semicircle-shaped constellation called
the northern Crown located between these
two larger
constellations if you trace the northern
Crown starting from the botes
constellation and ending on the side
closest to Hercules the blaze star
should appear just below the last star
of the northern crown and if you have
access to a powerful amateur telescope
or can visit a local Observatory you may
even be able to spot this binary star
before the Nova begins to be able to
truly compare these nov remind us that
even Stars which can seem Eternal and
unchanging have astonishing life cycles
that can include drastic changes and
dramatic explosions like a cosmic
firework show rare and awesome each Nova
provides a unique opportunity for
astronomers to gather data that will
help to refine our understanding of
Stellar Evolution binary star systems
and explosive Stellar phenomena this
Nova will be one of the most exciting
astronomical events we will get to see
in our lifetime so keep an eye on the
night sky and maybe feel just that
little bit luckier to be alive and to be
able to experience this here on
Earth you have probably heard that
modern-day science believes the universe
to be 13.8 billion years old it seems
rather unfathomable how anyone can come
to that conclusion but actually the how
is not too difficult to understand
people just don't generally ask the
question either they scoff at it or they
accept it as truth in this video we will
explore this how but also throw a
spanner in the works due to the newly
discovered age of one of our local Stars
called the methusa star which apparently
is older than the age of the
universe so 13.8 billion years old how
did we come to that figure we currently
see the universe is expanding and
cooling everything is moving away from
everything excluding forces like gravity
keeping things together the speed of
this expansion is known as the Hubble
constant and currently the universe is
expanding at a rate of 880,000
kmph per million light
years so the obvious conclusion from an
expanding universe is that matter is
becoming diluted there's more space in
between
things a less obvious result of the
universe expanding is the stretching of
light wavelengths known as red shift
what started off as extremely high
energy and high frequency waves emitted
soon after the Big Bang have become
stretched finally reaching us as less
energetic microwaves known as The Cosmic
microwave background
radiation it's also why the James web
Space Telescope is an infrared telescope
as photons of light emitted by galaxies
billions of light years away have had
their frequency shifted to the red so
much that we need need an infrared
telescope to observe
them a photon contains energy and a
higher frequency wavelength means more
energy which means it is hotter lower
frequencies mean it is less hot hence
why we say the universe was once dense
and hot but now it's bigger but cooler
but how does knowing this help us work
out the age of the universe well we do
need to assume a few things about the
universe first
one the universe is uniformly dense on
the largest scales this seems wrong it's
clearly not uniform there are super
clusters full of densely packed galaxies
and super voids containing not much at
all however like stars in a Galaxy zoom
out far enough and suddenly everywhere
looks the
same so we assume the universe is
homogenous as a result of that not only
is matter distributed evenly but two we
also assume the universe's laws and
properties are the same throughout in
any direction and three we assume the
Big Bang occurred in all locations
everywhere at once if you hadn't heard
that before you can check out my video
about it here under the laws of general
relativity if these three things are
true then there is a connection between
how old the universe is and how it
expanded throughout its
history with these assumptions we can
get distance and brightness measurements
between objects like stars Supernova and
galaxies for instance why dwarf
Supernova always appear about the same
brightness if an observed Supernova is
dim compared to what we expect it is
because it is further away finding out
how dim tells us how far away it is and
thus how far back in time we are
looking we can also look for
fluctuations in the cosm microwave
background radiation which is a snapshot
of the universe only a few hundred
million years after the big bang
comparing it to Galaxy clusters we see
today there is a correlation so we can
see how it's fluctuated to understand
how the universe evolved and
expanded based on the expansion of the
universe today and how it did expand we
now know the universe is 68% Dark Energy
27% dark matter and 5% observable matter
but what is dark matter and dark
energy we really don't have much of an
idea however we can see their effects
dark energy is believed to be the
driving force behind the universe's
expansion as the expansion would have
slowed down by now without
it and dark matter is gravitational
force we can't account for galaxies and
Galaxy clusters in particular
seem to have a lot more mass than they
should meaning the gravitational pole is
stronger dark matter is what must keep
Galaxy filaments
together we can observe its influence in
fact we can even map out its mass
distribution like in this image but we
don't know what it is we can't observe
it but for the purposes of this video we
don't need to know what it is only what
it does to be able to work out the
universe's
age so we know the current rate of the
universe's expansion or the Hubble
constant we know how that red shifts
light we know the composition of the
universe and we know its properties we
can see how Galaxies have evolved over
time we look for fluctuations in the
cosmic microwave background radiation we
can use all of this together to
extrapolate back to the earlier stages
of the Big Bang using three different
instruments or looking at different
aspects of the universe all the answers
have come back roughly the same 13.8
billion years with an estimated 99%
accuracy but there's another method
which has thrown a bit of a spanner in
the works and that is to measure the age
of stars certain types of stars are very
short-lived going Supernova in a matter
of a few million
years others could last for trillions of
years not that we've seen one that old
for obvious reasons in fact following
the evolution of stars we haven't really
seen any older than about 13.2 billion
years old but this does mean that long
live stars that formed as matter was
coalescing shortly after the big bang
would certainly still be around today
and this is where our friend Methuselah
comes in Methuselah is a metal poror
star meaning it is very old and
incredibly rare and most special of all
it is only only about 200 light years
away from us which means we can examine
it relatively closely based on its
Evolution it is an estimated 14.5
billion years old give or take about 800
million years this means it might have
disproved the 13.8 billion
figure so do we really know how old the
universe is roughly it wouldn't be
surprising to see this figure change as
our technology improves we have the W1
and James web space telescopes coming
out soon with specific mission
objectives to peer deep into the
universe's past exciting times although
I don't think we'll see this figure vary
than more than about 1 billion years in
either
direction research is still in very
early days in this field even if it has
been a topic of research for a while to
be honest though I'm so impressed we
have got this far who would have even
thought we could come up with any figure
a few hundred years ago all this may
throw out more questions than it
answered but that is science in a
nutshell the ongoing search for
truth the Hubble Space Telescope has
been in operation for an astonishing 28
years and during this time it has imaged
some spectacular sides of our galaxy and
Beyond it is truly a Marvel of
technology and has helped us improve our
knowledge of the universe we live in to
no end this includes understanding the
many different types of stars in our
galaxy in various stages of their
development in this episode we are going
to have a look at some of the most
special and peculiar Stars it has seen
and believe me when I say that some of
these are simply
breathtaking number 35
hh34 this amazing site found near the
Orion nebula is a herbig harrow object
or an emission jet from an extremely
young star that is still in the earlier
stages of its formation you can see the
star here still tucked inside this
molecular
cloud the Orion Nebula is one of the
closest H2 nebula or Star forming region
to us which means we can see stars in
the process of being formed reasonably
close
up the star is releasing this extremely
hot J of gas from one of its poles which
speeds through space at hundreds to
thousands of kilom per
second eventually this jet hits colder
material heating it up which is what you
can see here at the bottom
left for astronomical standards this is
a very shortlived event only lasting a
few thousand
years number 36 more stars in the
process of being formed this is XZ Tori
and it's neighbor Stars HL Tori and V1
1213 Tori to me this image is one of the
most mindblowing images Hubble has ever
taken the birth of stars taken against
this backdrop of a dark molecular
cloud let's have a look at what's going
on this is XZ Tori a star system
containing two stars about the distance
of our sun and Pluto
apart for reasons unknown to scientists
these stars have ejected a huge bubble
of hot gas seen here this bubble is
expanding at a rapid rate as seen over
the course of 5
years this over here is HL Tori another
very young Tori star this star has a
protoplanetary dis surrounding it
meaning planets are likely still in the
process of forming
here it's also ejecting another herbig
Hara object number 150 shooting over in
this
direction and finally we find V1 1213
Tor a variable star with a spectacular
disc surrounding it at a side on angle
to us the dis obscures the view of the
star
itself but it's reflected light comes
off the surrounded gases and hh30 the
hair big Harrow object shooting off in
both directions away from the
Star an amazing image found near the
Taurus
constellation number 37 okay just one
more Proto star
hh24 the star itself is again Hidden
Away by the blanket of the molecular
cloud it is surrounded and being fed by
by but what is clearly evident is the
lightsaber likee jet of gas being
blasted away from the star in both
directions it shares a lot of
similarities to the other herig Harrow
objects in this episode but the image
itself is so impressive
nonetheless this protostar is also found
near the Orion
Nebula number 38 LL pegasi we're moving
on now to Stars near the end of their
lives no not this bright star but rather
this dark and mysterious spiral next to
it this is one of the most perfect
geometrical objects formed in space but
what is
it this is actually a pre-planetary
nebula basically a massive star found
behind all this dust in the center is
shedding some of its mass potentially
before it erupts into a planetary nebula
the difference between a pre-planetary
nebula and a planetary nebula is that
pre-planetary nebula is a reflection
nebula meaning it is illuminated By the
Light reflecting of it whereas a
planetary nebula consists of extremely
hot ionized atoms which produces its own
light in this image the material form in
the spiral is moving at 50,000
kmph and by combining this speed with a
distance between the layers is estimated
to produce a ring roughly every 800
years they believe this is directly
related to the fact that this is a
binary star system the orbital period of
which is thought to also be 800 years
this means the spiral is the result of
the orbital motion between the two stars
as one sheds its
mass number 39 another pre-planetary NE
NE is HD
44179 a unique nebula with a rectangular
or an X shape this nebula is really hard
to see from a ground telescope due to
the Earth's atmosphere and is one of the
situations where having Hubble in Space
is really
useful this pre-planetary nebula has
really baffled scientists who don't know
the exact mechanics of how this
structure
formed but there is evidence that this
is due to another close binary star
system where the star about the mass of
our sun Shedd in its mass before it
turns into a white
D it's the remaining white dwarf that
will eventually radiate UV light
ionizing the ejected gas to become a
planetary
nebula number 40 let's have a look at a
completely different type of star with
RS puppet this bright star at the center
of the image is our Focus in this image
and there is something very unusual
about this star it is a variable star
known as a sephi
variable this means it varies in
brightness by a factor of five once
every 40 or so days because this star is
surrounded by a beautiful dust structure
we can see the variable nature of this
star through a light Echo light travels
extremely fast but it still takes a long
time to get across astronomical
distances
this means we can see the procession of
light traveling away from the star with
some rings being dark as the star was
dimmer and some rings being brighter as
the star
brightened Hubble imaged RS puus over a
5we period and you can actually see this
light Echo
pulsing all in all a ghostly yet
beautiful
image number 41 AG
Karina this star is another variable
star but it is one of the brightest in
the Milky Way because it is so bright it
is also shortlived as it is Shedd in its
mass through solar winds at an
incredible rate and its speeds of up to
7 million km
hour much of the surrounding material
around this star is part of the ejected
mass of the star being further sculpted
by the solar winds as you can see
one day this star will become a wolf
rier star a type of star millions of
times more luminous than our sun however
right now it's so hot that it isn't
visible to the naked eye as much of its
output is in the
ultraviolet number 42 NGC
4993 so far all the stars we've looked
at have been found in our own galaxy
outside the Galaxy in individual stars
are pretty hard to observe
typically but sometimes cataclysmic
events happen in other galaxies that are
so big we can observe it millions of
light years away and this is what
happened with NGC
4993 where something even more
spectacular than a supernova happened a
killer NOA in August
2017 ligo detected gravitational waves
from the Collision of two neutrons stars
and within 12 hours the source of these
gravitational waves had been discovered
considering it is so bright and evident
140 million light years away I can't
imagine what it would have been like
from within the same
galaxy these neutron stars will have
combined to form a black hole and the
resultant kilonova explosion will have
emitted electromagnetic radiation in
every frequency from radio waves to
gamma rays interestingly It is believed
that neutron stars colliding could be
the main source of heavier elements such
as gold in the universe if that is true
it gives your jewelry a bit of A New
Perspective I
think this image is a small section of
what is known as the tarantula nebula
the tarantula nebula is a huge
impressive nebula found in the large
maganic Cloud a satellite Galaxy to our
own some may argue it isn't as pretty as
some of the other nebula we've looked at
so far but I must say it does look good
in its own right but if it isn't its
looks that make this nebula stand out
what is it and what sets it apart from
anything we've looked at so far well
we'll come back to that let's first of
all give you some
context so where is it well this is the
large maganic Cloud the largest of the
Milky Way satellite galaxies and as you
see it has a lot of nebula the one we're
focusing on the tarantula nebula is the
brightest and biggest nebula in this
galaxy and it really is bright I
selected this image because it still
shows some of its details most other
images I found show it as this bright
Overexposed spot it's so bright that if
this nebula was as close to us as the or
nebula in our own Milky Way it would
cast Shadows at night let's zoom in to
find find out
why the tarantul nebula is currently
undergoing extreme star formation in
fact it's the most active star forming
region in the whole local cluster of
galaxies to its Center is a region of
stars known as NGC
2070 the central concentration of stars
known as
r136 it's this star cluster that
produces most of the energy to make this
nebula visible it's a really big cluster
with an estimated
450,000 solar masses contained within it
now if you've ever wondered what the
most massive and brightest known star
was look no further one of the stars in
this cluster known as
r136
A1 is the most massive and brightest
star on record with some pretty
incredible statistics it's a Wolf rier
star
315 times the mass of the Sun and 8.7
million times more luminous it is also
one of the hottest stars at 53,000
De while it is the most massive star it
isn't the biggest although its size
still dwarfs the Sun as always with
these massive stars it will only be
shortlived and it will almost certainly
become a black hole at the end of its
life in the meantime it's shed in its
mass through solar wind at a very fast
rate since its birth it's thought it's
already lost 50 solar masses to space
overall the r136 star cluster is thought
to be only about 2 million years old
it's currently merging with another
close by cluster the two clusters
together making up NGC
2070 you may not think that there are
enough stars in this image to make up
450,000 Sol masses but these blue stars
you see in this image are only the very
brightest O type stars in the cluster
interestingly there is a star that
belongs to this cluster which isn't
found anywhere in the area if we zoom
out a bit you'll find this star over
here it's called 30 dadus
016 and the young star only 1 to 2
million years old may have traveled
about 375 light years from its suspect
Ed home in the star cluster
r136 and it's still traveling about
400,000 kmph but how did it get all the
way out here the theory is that it was
part of a binary star system when
another even more massive star entered
the system and kicked out the now
homeless star these other stars would
have had to have been extremely massive
as 30 dadus
016 is no minnow at a suspected 9 0
solar
masses it is now an Explorer destined to
travel the far reaches of the large
maganic
Cloud there is another old star cluster
found in the tarantula nebula called
Hodge
301 it is roughly 20 million years old
with some Stars 10 times as old as those
found in
r136 within this star cluster there are
thought to have been at least 40 stars
that have gone Supernova whereas in in
r136 there have been none this is
because of the age of hodj 301 some of
the shortest lived stars have already
gone through their entire life cycle
more stars in this cluster are on the
verge of exploding in a supernova 2 so
watch this
space the original image we looked at is
further away still from the center of
the tarantula nebula although it's still
part of it in an area called NGC 2060
found over here it's a star cluster 2
although the Stars here are much more
Loosely dispersed than in r136 and Hodge
301 in fact these stars are no longer
gravitationally bound to each other and
in a few million years the Stellar group
will disperse completely it's currently
about 10 million years old and there are
some very interesting things found in
this area the first I'll mention is that
the whole of NGC 2060 Z is a supernova
Remnant about 165 light years across
it's estimated that the Supernova
occurred about 4 to 5,000 years ago and
consistent with this Theory a pulsar
neutron star is found in this area here
around the same age as the Supernova
it's not really visible invisible light
as it emits x-rays which means you need
the xray telescope Chandra to see it and
it's right in the middle of this bubble
the bubble is itself is the Supernova
Remnant the Pulsar rotates exceptionally
fast once every 16 milliseconds
interestingly it's not the fastest
rotating star in this region that
Accolade belongs to this runaway blue
super giant vft
ts102 it's actually the fastest rotating
star that we know of rotating a speedy 2
million km
hour this is 100 times faster than the
rotational speed of
it spins so fast that the star is
flattened with an equatorial disc
extending out due to centrifugal
forces it is suspected that this runaway
star actually was part of the same
system as the Pulsa and would have had a
hand in its Supernova explosion before
the Supernova there would have been two
blue stars orbiting one another one
would have evolved into a red super
giant and as it expanded it would have
started feeding ITS m Mass into the
other star speeding the rotation of the
other once the red super giant exploded
in a supernova it ejected the other star
at a tremendous speed into space vft
ts102 fits this model as it's spinning
rapidly whilst also hurtling through
space in relation to its Stella
neighborhood zooming out further again
we are getting to the edge of the
tarantula nebula at its longest points
the tarantula nebula is incredible 1,000
light years across I already mentioned
this nebula is the most active star
forming nebula known as an H2 region in
our local cluster of galaxies but it is
also the biggest if it was as close to
us as the Orion Nebula it would be twice
as big in the sky as the Big Dipper and
because it's so bright it would even be
visible during the day at the far edge
of this nebula is perhaps its most
remarkable visual spectacle it's called
SN
1987a and it's a supernova Remnant it is
a lot younger than any of the other
Supernova we've looked at so far in fact
it's less than 30 years old the light
from this Supernova hit Earth in 1987
and was visible to the naked eye it was
the first Supernova observed since the
1600s and the only Supernova observed
that we've had a close look at using
modern day telescopes when it exploded
it was a blue super giant which means it
was only about 1/10th of the brightness
of a red super giant Supernova hav't had
the chance to look at it now I bet
you're wondering what these Rings could
be well they are the mass thrown off by
the star through Stellar winds coughing
and splutter in its innards out
thousands of years before the
Supernova the initial Flash from the
explosion lit the Rings up at first but
when the Supernova shock wave hit them a
few years later they lit up again due to
interaction with the Rings and the
debris from the shock wave SN
1987a is now a true Supernova Remnant in
the vein of copia a illuminated not by
the explosion of the star but by
continual processes between the debris
of the Supernova and the material Beyond
it this artist's illustration of SN
1987a is based on real data and reveals
the cold inner regions of the exploded
Stars remnant
this patch here in red where tremendous
amounts of dust were detected and imaged
by the Elma telescope it's in this dust
that the leftover Pulsar could be hiding
because nothing has been detected where
the Pulsar should be another option
could be that it didn't turn into a
pulser at all but it's actually now a
black
hole thanks for watching I really want
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