Welcome to Cosmos in a Pod, Space, and Astronomy series,
episode seven.
Get ready for a deep dive into the universe's
most spectacular light shows.
We're talking supernovae, the explosive death of stars.
Events so bright they can outshine entire galaxies
for a short time.
It's really hard to grasp the sheer power of these events.
We're talking about a sudden release of energy.
It just dwarfs anything we can even imagine creating
here on Earth.
I can only imagine.
That's mind blowing.
It's like one firework outshining a whole city
at night.
So why should we down here on Earth
care about something so far away, something seemingly
unrelated to our lives?
Well, that's where it gets really fascinating.
Supernovae, as destructive as they seem,
they're actually responsible for creating
the elements that make up everything around us,
including us.
Think about it.
The carbon in your cells, the oxygen you breathe, even
the iron in your blood, it was all
forged in the heart of a star and flown out
into the cosmos by a supernova.
So we're all made of stardust.
So amazing.
So how does a star go from congly burning
for billions of years to suddenly exploding
with such incredible force?
Well, it's not exactly sudden.
There's a buildup to this cosmic grand finale.
And the path depends on the type of supernova.
You mentioned different types.
Walk me through them.
What's the first one?
The first type, known as a type I supernova,
it typically happens in a binary star system,
two stars orbiting each other.
Now, one of these stars is a white dwarf,
basically the dense leftover core of a star that's
already run out of fuel.
If this white dwarf is close enough to its companion star,
it starts pulling material off its neighbor.
Like a cosmic vampire star.
Exactly.
Imagine this white dwarf slowly siphoning away
material from its companion, growing larger and denser
over time.
Eventually, it reaches a critical point.
It's called the Chandrasekhar limit.
The Chandrasekhar limit.
What happens at that point?
Is that what triggers the explosion?
Exactly.
You can think of this limit like a tipping point.
Once the white dwarf exceeds this mass, it becomes unstable.
The internal pressure and temperature skyrocket,
and it ignites a runaway nuclear reaction
that completely obliterates the white dwarf
in a blinding flash of light.
So it's like a stellar pressure cooker gone haywire.
Yeah.
You mentioned that astronomers use these type I supernovae
for something else, like being a cosmic measuring stick.
You're right.
Here's why type I supernovae are so useful.
They all explode with nearly the same intrinsic brightness.
Think of them like light bulbs of a known wattage.
If you have 100 watt bulb and you see it shining dimly,
you know it's far away.
If it's super bright, it must be close.
So by comparing the actual brightness of a type I
supernova to how bright it appears from Earth,
astronomers can calculate its distance.
Precisely.
They're called standard candles.
And they've been instrumental in helping us map out
the distances to far away galaxies,
and even understand how fast the universe is expanding.
That's amazing.
A single type of exploding star can tell us so much
about the vastness of the universe.
So that's type I. What about the other type of supernova,
the one that comes from massive stars?
Ah, yes.
Tag two supernovae.
This is the grand finale for stars, at least eight times
more massive than our sun.
Their story begins with fusion, the heart
of what makes a star shine.
Fusion, right.
That's where stars combine lighter elements
into heavier ones, like building blocks.
Exactly.
These massive stars are like giant furnaces,
constantly fusing hydrogen into helium in their cores.
But eventually, they run out of hydrogen fuel.
Then they start fusing helium into carbon,
then carbon into oxygen, oxygen into silicon.
It's a step-by-step process, building up
heavier and heavier elements.
Until they reach iron.
You mentioned iron was significant.
Why is that?
Iron is the end of the line.
It's the most stable element, meaning fusing iron
doesn't release energy like the other elements.
In fact, it requires energy.
So once a massive star's core is filled with iron,
it's basically out of fuel.
And it can no longer support its own weight.
Against the crushing force of gravity.
So what happens then?
Does the whole thing just collapse?
It does.
And it happens incredibly fast.
The core collapses in on itself.
The result is an unimaginable shockwave
that rips through the star, blasting its outer layers
into space with incredible force.
And that's the supernova we see.
That's it.
That spectacular explosion.
That brilliant light that can outshine an entire galaxy.
That's the type 2 supernova.
OK.
So the outer layers of the star are blasting into space.
Yeah.
What happens to the core itself after this dramatic collapse?
Is it just gone?
Not necessarily.
The fate of the core depends on the original mass of the star.
For smaller massive stars, the core
gets squeezed into an incredibly dense object
called a neutron star.
We've talked about those before.
They're like giant atomic nuclei just a few miles across.
But with the mass of an entire star packed
into that tiny space.
Right.
Neutron stars.
Those mind-bogglingly dense objects.
But you said it depends on the original mass.
What happens to the cores of the really massive stars?
For those truly massive stars, the core's collapse
doesn't stop at a neutron star.
It keeps collapsing, becoming denser and denser,
until it essentially disappears from our universe,
forming a black hole.
A black hole.
So depending on its size, the star gets a dramatic exit.
As either a super dense neutron star or a mysterious black
hole.
Talk about going out with a bang.
But wait.
I thought we were talking about how supernovae create things.
This all sounds pretty destructive.
You're right.
Supernovae are incredibly powerful and destructive events.
But they're also creators in a sense.
Think about all those elements that
were forged in the star's core over its lifetime.
They get blasted out into space by the supernova.
That material enriches the surrounding interstellar
medium, seeding it with the building blocks for new stars,
new planets, even life itself.
So in a way, these supernovae were like cosmic gardeners,
scattering the seeds for new life and new worlds.
That's a great way to put it.
Supernovae are essential to the cycle of cosmic evolution,
a fundamental part of how the universe works.
Wow.
This is fascinating.
Are there any specific supernovae
that we've actually observed and learned from, like famous ones?
Absolutely.
There are quite a few famous supernovae.
Take the Crab Nebula, for example,
this stunning cloud of gas and dust.
That formed from a supernova observed
by Chinese and Arab astronomers way back in the year 1054.
Wait, they saw a supernova almost 1,000 years ago.
They did.
It was so bright, it was visible during the daytime for weeks.
The Crab Nebula is what's left of that explosion.
And it's still expanding today, a beautiful and eerie reminder
of the power of these cosmic events.
That's incredible.
What other supernovae have astronomers
been able to study?
A more recent one, SN 1987A, which happened in 1987,
as the name suggests.
It occurred in the Large Magellanic Cloud, a nearby galaxy
that orbits our own Milky Way.
So it was relatively close to us, astronomically speaking.
Yes.
It was the closest supernova observed
in modern times, which allowed astronomers to study it
in incredible detail.
We learned a lot about the physics of supernova explosions
and the formation of neutron stars from that event.
I can imagine.
But if these supernovae are so rare,
how do astronomers even find them in the vastness of space?
Do they just happen to look in the right direction
at the right time?
That would be incredibly lucky.
No.
We have much more sophisticated methods these days.
Modern telescopes and dedicated sky surveys
are key to finding these cosmic explosions,
even in distant galaxies.
So what kind of technology are we talking about here?
Well, there's a Hubble Space Telescope, of course,
which has captured some incredible images of supernova
remnants.
And then there are ground-based observatories,
like the Vera Rubin Observatory.
It'll be coming online soon.
What's special about the Vera Rubin Observatory?
It's designed to scan the entire sky every few nights,
looking for any changes, including new supernovae.
It's going to revolutionize our understanding of these events.
That's exciting.
So it sounds like we have these incredible tools
for finding supernovae.
But what about studying them?
How do astronomers actually learn about what's
happening in these explosions?
It all comes down to analyzing the light.
When a supernova explodes, it emits light
across the entire electromagnetic spectrum,
from radio waves to gamma rays.
Astronomers use different types of telescopes
to capture this light and then break it down
into its component wavelengths.
Like a prism splitting sunlight into a rainbow.
Exactly.
By studying the patterns in this light,
we can learn about the chemical composition of the supernova,
its temperature, its speed, even how
the explosion itself unfolds.
Wow.
It's like they're piecing together a cosmic crime scene,
using light as their clues.
That's a great analogy.
And with each new supernova we observe,
we gain a deeper understanding of these events
and their role in the evolution of the universe.
It's truly remarkable what we can
learn from these distant, fleeting flashes of light.
This has been absolutely fascinating.
So glad we're not too close to any
of these potential supernovae.
It sounds like it'd be a pretty rough day on Earth
if one went off nearby.
You're telling me.
But don't worry.
While supernovae are essential to the universe's evolution,
we're at a safe distance from any potential candidates
in our galactic neighborhood.
So we can appreciate their beauty and power from afar.
Glad to hear it.
I think it's time for a quick break.
But when we come back, we'll continue our supernova
exploration with even more cosmic insights.
Stay tuned.
Welcome back to Cosmos CinePod.
I hope you're ready for more supernova talk,
because we've only just scratched the surface.
I am so ready.
You've got me totally hooked on these cosmic fireworks.
Before the break, we were talking
about how astronomers actually find and study supernovae.
It's amazing what they can learn just by analyzing the light.
But you also mentioned that supernovae
are responsible for creating some of the heavier elements
in the universe.
Can you elaborate on that?
Absolutely.
We talked about how stars fuse lighter elements
into heavier ones in their cores, right?
Our sun, for example, can produce elements
up to carbon and oxygen.
But the really heavy elements, think
of gold, platinum, uranium, those
are forged in the intense heat and pressure of supernova
explosions.
So that gold necklace I'm wearing,
it's actually made of supernova remnants.
That's kind of mind blowing.
You could say that.
Every atom of gold on Earth and everywhere else in the universe
was created in a supernova explosion billions of years ago.
We literally carry pieces of stars within us.
Wow, that's a powerful thought.
So these supernovae are not only responsible for creating
the elements we need for life, but also
some of the most precious and valuable materials we have.
They're like cosmic alchemists turning stars into gold.
That's a great analogy.
And it reminds us that even the most violent and destructive
events in the universe can have creative consequences,
shaping the world we know.
Speaking of those violent events,
I have a question for you.
Earlier you said that a supernova can briefly
outshine an entire galaxy.
Just how bright are we talking here?
Yeah, I'm still trying to wrap my head around that.
It's hard to imagine something outshining billions of stars.
Well, to put it into perspective,
the energy released by a typical supernova
is equivalent to the total energy output of our sun
over its entire lifetime.
Imagine all the energy our sun will produce
over billions of years, released in just a few weeks or months.
Whoa, that's an incredible amount of energy.
No wonder they're so bright.
But what happens after a supernova fades away?
What's left behind?
It depends.
As we discussed, a type 2 supernova,
the death of a massive star, can leave behind either a neutron
star or a black hole.
Right, the super dense leftovers, or a cosmic vacuum cleaner.
What about type I supernovae, those white dwarf explosions?
In those cases, there's often nothing left behind.
The white dwarf is completely obliterated in the explosion,
leaving behind only an expanding cloud of gas and dust.
So it's like the ultimate disappearing act, poof, gone.
You could say that.
But even though the star itself is gone,
the material it blasts out into space
continues to interact with its surroundings.
It can influence the evolution of galaxies,
even trigger the formation of new stars.
So even in their death, supernovae
contribute to the ongoing cycle of creation and destruction
in the universe.
It's like a never ending story.
Exactly.
Each supernova leaves behind a unique fingerprint,
a story written in the patterns of gas and dust,
that we can study and learn from.
It's like a cosmic echo of a star's life and death.
This is all so fascinating.
It makes you appreciate the interconnectedness of everything
in the universe.
But I have to admit, I still have a lot of questions
about supernovae.
For example, how often do they actually occur?
I mean, are we likely to see one in our lifetime?
Well, supernovae are relatively rare events,
at least in our own galaxy.
Astronomers estimate that a supernova
occurs in the Milky Way about once every 50 to 100 years.
So we're due for one soon?
Well, soon is a relative term in astronomy.
But it's certainly possible that we could witness
a supernova in our lifetime.
Wow.
I can only imagine what a sight that would be.
But you mentioned that we can observe supernovae
in other galaxies, right?
So even if we don't see one in our own galaxy,
we can still study them.
Yes.
And thanks to modern telescopes and surveys,
we're detecting supernovae in other galaxies all the time.
In fact, astronomers discover thousands
of supernovae each year.
Thousands.
That's incredible.
So while they're rare in our own galaxy,
they're actually quite common across the universe as a whole.
Exactly.
And by studying these distant supernovae,
we can learn a great deal about the evolution of stars
in galaxies and even about the fundamental properties
of the universe itself.
So each supernova is like a unique window
into the distant past, offering clues
about the history of the cosmos.
It's almost like reading a history book written
in starlight.
That's a beautiful way to put it.
They're like cosmic time capsules,
carrying information about the conditions of the universe
billions of years ago.
It's amazing to think that we can access that information
from our little planet here on Earth.
But we've talked a lot about the scientific aspects
of supernovae.
What about the cultural impact?
Have these events had any influence
on human history or mythology?
That's a great question.
And the answer is definitely yes.
Throughout history, people have been awestruck
by the sudden appearance of bright new stars in the sky.
Imagine seeing a new brilliant point of light appear.
Where none was before, long before we understood
what was happening, it must have been a truly awe-inspiring
and perhaps even frightening sight.
I can imagine.
It makes sense that cultures would incorporate
these selectual events into their myths and legends.
Exactly, and they did.
Many cultures incorporated supernovae into their stories.
For example, in some ancient cultures,
supernovae were seen as omens, portending
either good or bad fortune.
Oh, like celestial messengers from the gods.
In a way, yes.
They were seen as signs from the gods
or as messages from the universe itself.
It's a testament to the power of these events
to capture the human imagination.
It seems like supernovae have always
had a way of making us look up and wonder about our place
in the cosmos, even when we didn't fully
understand what they were.
Absolutely, and even today.
With all our scientific knowledge,
there's still a sense of wonder and awe
when we witness the death of a star
and the birth of something new in the universe.
It really makes you think about the grand scheme of things.
I couldn't agree more.
There's something truly poetic about the cycle of life
and death playing out on such a grand scale.
It's a reminder that we are all part of something much larger
than ourselves.
Well said.
And on that note, I think we've covered a lot of ground today,
from the science of supernovae to their cultural impact.
But before we wrap things up completely,
we have one more exciting aspect of supernovae to explore.
You've got my attention.
What else is there?
We're going to delve into how these stellar explosions can
actually help us understand the universe on an even grander
scale.
We're talking about cosmology, the study
of the origin and evolution of the universe itself.
Oh, this sounds good.
I'm ready to dive even deeper.
Welcome back to Cosmos CinePod.
We're wrapping up our deep dive into the fascinating world
of supernovae.
And I'm ready to hear how these stellar explosions can
shed light on the entire universe.
You were about to explain how supernovae connect
to cosmology, right?
Exactly.
It might sound surprising.
But these distant fleeting events
can help us understand the universe's biggest secrets.
Specifically, type Ia supernovae,
those white dwarf explosions we talked about.
They're incredibly valuable tools for cosmologists.
OK, remind me again, why are type Ia supernovae so special?
You said there were standard candles.
Right, because they all explode with nearly
the same intrinsic brightness.
We can use them to measure distances
across the vastness of space.
Think about it this way.
If you have two identical light bulbs, but one appears dimmer,
you know it must be farther away.
Right.
So by knowing the actual brightness of a type Ia
supernova and comparing it to how bright it appears to us,
we can figure out how far away it is.
But how does that help us understand
the universe as a whole?
It's all about the expansion of the universe.
Remember, we live in an expanding universe
where galaxies are constantly moving away from each other.
By observing type Ia supernovae in distant galaxies,
we can not only determine their distances,
but also how fast they're moving away from us.
So it's like, we have these cosmic mile
markers scattered throughout the universe.
And by watching how they move, we
can trace the history of the universe's expansion.
Exactly.
And what's even more amazing is that these observations
led to a groundbreaking discovery.
The universe's expansion isn't constant.
It's actually accelerating.
Wait, accelerating?
You mean the galaxies are moving away from each other
faster and faster over time?
That's wild.
What's causing that?
That's the million dollar question.
It leads us to one of the biggest mysteries
in modern cosmology, dark energy.
Dark energy?
What is that exactly?
It's this hypothetical form of energy
that seems to permeate all of space,
acting like a sort of anti-gravity,
pushing everything apart.
We don't know exactly what it is or where it comes from.
But it's thought to be responsible for the accelerated
expansion of the universe.
So it's like an invisible force counteracting gravity
on a cosmic scale.
That's mind-boggling.
It really is.
And while we still have a lot to learn about dark energy,
its discovery wouldn't have been possible without those distant
type Ia supernovae.
Acting as our cosmic guides, they've
opened up a whole new realm of exploration in cosmology.
It's incredible how much we've learned about the universe.
Just by studying these exploding stars,
we've gone from understanding the elements they create
to mapping the expansion of the universe.
It really highlights the interconnectedness
of everything in the cosmos, doesn't it?
It absolutely does.
And it underscores the importance
of continued scientific exploration and discovery.
Who knows what other secrets these cosmic explosions hold,
just waiting to be uncovered.
That's a great point.
Well, I think that's all the time we have for today.
Thank you so much for joining us on this cosmic journey.
I hope you learned something new about these incredible events.
If you enjoyed this episode, be sure to follow and subscribe
to Cosmos in a Pod for more deep dives into the wonders
of the universe.
Until next time, keep looking up.