February 13, 2020 • 43 mins
We're taking a deep dive into the subject of supernovas. What causes them? What do we know about them and can they harm us here on earth.?
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Episode Transcript
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Speaker 1 (00:08):
Hey, Daniel, do you like looking for shooting stars? I
do because sometimes the nice sky is really static, it
seems frozen, and so it's exciting to see something streak
and flame out across the sky. You know they aren't
really stars, right, Um? I am aware, thank you very much.
I also know that nobody's actually shooting those stars as
(00:29):
far as we know. You know aliens. Hello, you're going
to hit the aliens button before me. But it would
be cool to actually see a star explode, you know
what I mean. You're looking at at the sky and
suddenly one of them just goes Yeah, as long as
it's not our star, would be pretty fun to watch.
(01:04):
Hi am poor handmade cartoonists and the creator of PhD comics. Hi.
I'm Daniel Whitson. I'm a particle physicist, and I'm the
co author of the book We Have No Idea, A
Guide to the Unknown Universe, book about all the things
we don't know about the universe. And you wrote it
with a really awesome and fun cartoonist, didn't you? I did,
in fact, and I was recently contacted by one of
(01:27):
our listeners and one of our readers in the Czech Republic,
who's reading our book in check, I hope it says
the same things. It doesn't English. Well, he actually told
me how to translate the title in check literally into English.
But how does it translate. Apparently it translates to we
don't even know fart about it. Really, the word fart,
(01:47):
isn't it? He says. It's a very common expression in
check for I don't know fart about that, and that's
the expression they chose for the title in check. Wow.
I wonder if we had named that, made that the
actual title in English, maybe we would assault, we would
dislike more copies. I don't know. Maybe the book would
kind of stink. But it's a really fun book. It's
all about the unanswered questions of the universe, all the
(02:09):
things we'd like to know about our lives and where
and where we live and how the universe began but
don't yet know. And so we hope on this podcast
to take you on a tour of what we do
and don't know about the universe, and maybe one of
you out there, a young budding scientist, will be the
one to figure out the answers. That's right. We bring
to you all the amazing mysteries of the universe, and
all the farts in the universe and all the mysterious
(02:31):
farts in the US parts, the ones that fortunately you
can't smell through this audio podcast. Well, welcome to Daniel
and Jorge Explain the Universe, a production of I Heart
Radio in which we examine them the amazing, the mysterious,
all the weird and wonderful things in our bonkers universe,
and we talk about them in a way we hope
entertains you and also teaches you something deep about the
physics of our universe. Yeah, we talked about all the
(02:55):
sort of a nice and beautiful and wonderful, inspiring things
that are out there in universe, the big and the small,
but we also talk about some of the crazy things
that happened. That's right, because the universe is dramatic and
it is violent, and when it wants to make a splash,
it goes big, it goes supernova, it goes hyper nova, hypernova. Yeah,
(03:16):
So to be on the program, we'll be tackling perhaps
one of the most um I don't know, violent or
you know, dramatic or you know, maybe interesting events that
happened out in the universe. And that happens quite a bit.
That's right. It's one of the most interesting and dramatic
things that can happen in our universe. One of the
things we've seen, the kind of thing that we can
(03:37):
even find in historical records that people in ancient times
noticed happening in the sky and wondered what it was
all about? Right, and then so the question is how
much do we know about it? How much do we
understand about this incredible event and what we can do
if one happens near us? Yeah, and the answer is
basically dig a hole and pray. All right, let's get
(04:00):
into that. So to be on the podcast will be
asking the question what makes a supernova blow explode? I
guess super what makes a supernova explode? Or what makes
a supernova a supernova? What makes a supernova so super? Yeah? Yeah,
(04:21):
why isn't it a super dupernova? Or well, you know,
the name nova is actually quite fascinating. It means new
and so super. So supernova is like something super and
new in the sky. It comes from people looking at
the sky and saying, hey, that wasn't there before, or
that's different, and it's pretty rare to see something change
in the sky. I mean, we're used to the patterns
(04:42):
of the seasons and the days and the nights and
all that stuff. But otherwise the stars, you know, their
lifespan is much longer than ours, and so to see
one dies pretty unusual. We'll be talking talking about supernovas
and what how what causes a supernova and how that works.
But it's basically the biggest explode shin you can have
in space? Right? Is that true? The whole universe? That's
(05:04):
the biggest explosion that happens. It's the biggest explosion we've
seen so far. I mean, the stars are one of
the biggest things out there. I guess you can imagine
a galaxy exploding, but it's hard to see how that
would happen. A galaxy nova. Nobody's ever seen that yet.
What would you call that an uber nova or over nova?
(05:25):
But I guess maybe it's the biggest explosion because you know,
stars are some of the most you know, energy pack
things out there, right, I mean that that can explode
like you don't see a black hole exploding. You don't
yet see black holes exploding. That would be fascinating. And yeah,
the key to having a big explosion is not just
being massive, having a lot of energy, but releasing it
(05:46):
very very rapidly. Right, That's basically what an explosion is.
It's like it's like a bomb. You want to deposit
a lot of energy and you want to do really quickly,
so you got a shock wave of action. And that's
the thing that makes supernova is exciting that they happen ly.
It also is the thing that makes them hard to
understand and hard to spot because we don't know it
precisely what causes the star to go supernova, and they
(06:08):
don't happen that often, so it's pretty rare to see
one's start to go oh wow. Really, we don't know
what cosses these supernovas. No, we have some general sense
for what happens during the supernova, and we'll dig into
it on today's podcast. But what makes it go now
and not next week. To predict when an individual star
will go supernova is not something we know how to do.
(06:29):
Nobody's pressing a switch that you can see. Yeah, they
don't annow it's a big countdown like NASA. You know,
t's not taking time bomb. No, and astronomers would love
to see a star like five seconds before superno, one
second before supernova the first moments, you know, that would
be fascinating, so you can catch it as it as
(06:49):
it's happening. Yeah, And there's actually a guy who was
watching the skies in two thousand and sixteen, an astronomer,
an amateur astronomer. He was just happen to be looking
at one star her through his telescope and he saw
it go supernova, like in real time. Wow. What are
the chances of that? Well, they're pretty low because it's
actually not that many stars that will go supernova, Like,
(07:10):
not every star ends up in a supernova. And of
course stars lived for a really long long time, and
so they calculated the odds is like one in ten
million or one in a hundred million that if you're
looking at a star or through a telescope, that you'll
be watching it go supernova. Oh. So this person was
looking at the star through his telescope or her telescope
and it went supernova as he was looking at it.
(07:31):
As he was looking at it. Now, of course this
time delay went supernova a long long time ago, but
the images from that supernova arrived on Earth as his
eyeballs were pointed at it. Oh wow, And so how
did he prove this. Did he have a about his
cell phone and took a picture of it? Yea, all
good amateur astronomers have cameras attached to their telescopes, so
(07:53):
he snapped some photos. Then, of course he alerted astronomers
who all pointed their telescopes at it to try to
catch a glimpse of the first moment to the star
going nova. What is that true? He actually took pictures
of it? Oh yeah, Oh wow, that's pretty interesting. Wow.
And so supernovas are sort of famous, like people have
heard of them. People know that they're a thing. They're
pretty dramatic. Their pr campaigns have been pretty good. Yeah,
(08:15):
they're there's sort of in the general consciousness for sure,
of I think culture and society. I mean, everyone knows
him as his stars exploding. Yeah, but I was curious,
you know, how much did people actually know about a supernova?
Did they know what really happens inside? Do they know
what causes it? Do they know whether we understand supernovas?
So I walked around campus here at you see Irvine,
(08:35):
and I asked folks what they knew about supernovas. Yeah,
so think about it for a second. You've probably heard
of supernovas, But do you know what causes them and
how they actually explode? Here's what people had to say.
I guess it's something to do with the star exploding.
When a star explodes, What makes it happened? Um, the
death of the star. Supernovas usually like an exploding star, right,
(09:00):
so what makes its age? Are you going to explode
when you get over? Who knows? I know that supermanovas
are when a star reaches the end of its life
and eventually the force of gravity overcomes the push from
the inside of the star and it collapses and then explodes.
I know they're in space and it's is it? Is
(09:21):
it when a star like implodes or something more? I
know that they are the final stage and stars. Okay,
what makes it happen? Eventually, the the it becomes too dense,
the elements that it creates in the in the middle.
At that point it collapses in on itself. And there's
a few things that can happen. But a supernova is
one of them. A supernova No, I don't alright? Cool,
(09:45):
So I think it sounds like everyone knows what it means,
Like it means the death or the explosion of a star. Yeah,
they knew that it marks the end of the life
of a star, but a few people have really a
sense for like what's going on inside the supernova? What
makes it happen? Why do stars die that way? Why
do stars die at all? Why don't they just burn forever?
So it's a big e explosion in space. And you're
(10:07):
saying it's rare, so only about one to three supernova's
per century or something like that in a typical galaxy. Yeah,
we have seen a lot of supernovas from Earth, but
almost all of them have been in other galaxies. And
that's because most stars will not go supernova. In a
galaxy like the Milky Way that has about a hundred
billion stars, only about one or two, maybe three will
(10:30):
go supernova in a hundred years. So it's not it's
pretty rare. Most stars don't go supernova. Most stars do
not go supernova. The fact that we've seen hundreds is
only because there are so many stars and so many
galaxies out there. But you know, we're lucky and we're
glad actually that they're not a lot of supernovas, because
they're pretty devastating. Oh I see, So if a supernova
(10:53):
goes off in a galaxy far away, we'll will actually
see it, like it'll outshine the whole galaxy and we'll
see it, uh, you know, take over the light from
the galaxy. That's right. It's a really dramatic event. It
can be as bright as the entire sum of all
the light from the rest of the stars in the galaxy.
And so it's like it like doubles the brightness of
(11:13):
a galaxy when it happens. And the most amazing thing
is that most of the energy from the supernova doesn't
even come out in the form of light, so you're
seeing a tiny fraction of this incredible explosion in the
visual spectrum. So if you see if you're looking at
a galaxy at any point and you see it certainly
bright up, it's because of a supernova inside of it,
like one of its hundred billion stars went boom. Yeah, precisely. Well,
(11:37):
let's get into it, Daniel, all right, um, and explain.
Let's explain to people what a supernova is. I guess
what's the technical definition of a supernova. Yeah, so technically
a supernova is the end of the life of some
kinds of stars. Now not all stars. In fact, most
stars will not go supernova. But it's essentially the star
explodes and it sends out most of the energy that's
(12:00):
stored inside of it out into space in the form
of electromagnetic radiation, so visible light, which is a tiny fraction,
and an enormous number of neutrinos, just like gobs and
gobs and gobs of neutrinos, and then also an enormous
amount of matter. This is like shock wave of just
stuff that gets spewed across the universe, like the shrapnel
(12:21):
and the grenade. Yeah, like the shrapnel and the grenade.
And it's good that that happens because that goes out
and that seeds other stars to form, and it spreads
the heavy metals that were burned inside that star out
into the universe, so you can get interesting things like
a rocky planets then life on them. Well that's interesting.
So it's not Supernova is not like an accident that
happens to a star. It thought like um, a star
(12:43):
is suddenly gets out of balance. It's like it's like
in the DNA of the star. You know, like once
you once you know what kind of story you are,
you will most likely go supernova or if you know
the kind of star you know you'll never get you'll
never go supernova. Yeah, it's sort of like that, and
it's not totally under good, but it's something like if
you know how much master is to a star and
(13:04):
you know what it's made out of, Like did it
start just from burning hydrogen because you're one of the
first stars in the universe, or do you already collect
the burning remnants of other dead stars and so you
have helium and oxygen and nitrogen and carbon and all
that stuff already. If you know that starting point, you
can almost always predict the life cycle of a star,
including whether it's going to become a black hole or
(13:26):
a neutron star, or goes supernova, become a white dwarf
or whatever. That's basically what determines it is like how
big a scoop of stuff did you get of the universe?
And what's in that scoop? Wow? And that the terms
your your whole life cycle. If you're a star, like
you're born and everyone already knows how you're gonna die.
Here's a baby. Oh, this baby is going to be
a rock star and it's going to you know, shine brightly,
(13:50):
but then it's going to go out in a blaze
of glory when he or sheet turns thirty two. Stars
are not nearly as exciting and variable as people are. Right.
They're much bigger, and they're much more dramatic, but they're
also simpler, and also they don't really interact with each other.
Like a star is pretty isolated. It's got its own
little pocket of stuff and it just sits there and
burns it until it can't burn it anymore. We know
(14:12):
it's gonna go supernova, but you can't predict when it's
going to go supernova. Yeah, these stars have some something
of a variable lifetime, and you know these events, the
supernov event happens really quickly. Remember that the like the
time scale for stars can be millions and billions of years,
but the supernova events, the time scale for that is
days and so days, days, and so it happens really quickly,
(14:35):
especially the first bit the explosion. We're talking seconds and minutes,
and so what triggers that to happen? Is it like
a clock that ticking down. Eventually it's just gonna happen
like that. You could predict it a million or a
billion years in advance, if you knew well enough. What
was happening inside the star or is there some like
quantum mechanical randomness that's happening, or is it triggered by
(14:55):
some external event, like the star becomes really fragile and
then you know, a path seeing shock away from something
else makes it go. We just don't really understand those
moments or you know, um like a planet falls into
it and that triggers it. Perhaps, Yeah, there are stars
like that that do get triggers from in falling material,
but we don't know exactly like when that happens. All right, well,
(15:17):
let's get into the mystery of what triggers supernovas and
what's actually happening when they explode. But first let's take
a quick break. Right, So we we've seen a couple
(15:39):
of these supernovas in the night sky, like without telescopes. Right,
there's a historical record of supernovas and in humanity's history. Yeah,
it's a big event in the night sky when something blows.
And back before people really understood what stars were, they
were still interested in looking at them and commenting about them.
And so you can go back in the historical record
(15:59):
and can find ancient astronomers writing about this and the
earliest one. It's called h B nine is from b
C and we see this an ancient ancient texts. They
talk about the appearance of a new star in the sky.
So they just called it HB nine. What were those
ancient people thinking they had acronyms and numbers for I
(16:20):
don't know, we don't know who was We know it
was some unnamed Indian astronomers. We call it h B nine.
But you know they wrote about it as a as
a new object in the sky. Well, what would we
see if if I happened to be looking at the
nice guy and a Superno, what just happened to you know,
occur while I'm looking at this guy? What would I see?
Would I see a star suddenly grow bright and fill
(16:42):
the sky with light? Or would just would it just
be a star that gets a little bit brighter. Well,
it depends on how close it is. Of course, the
star is gonna get millions and millions or even billions
of times brighter than it normally is. Like, would it
be dangerous to look at it? Yes, if you are
looking at a star that's going supernova in our galaxy,
it could be very dangerous. I mean, you could fry
(17:04):
all life on Earth. That's kind of dangerous. So yes,
looking at it would be bad, all right, Um, and
then what would would I see it go bright for
like a few seconds, for a few hours, for a
few days. So the light curve of a supernova looks
like very rapidly getting brighter and brighter over the period
of a few days and then gradually fading over the
(17:25):
period of a few weeks outter a few months. So
it wouldn't be like a sudden flash. You would get
a little bit of warning. You would get brighter and
brighter and brighter over a couple of days. Yeah, And
you can actually get a warning before the flash arrives
because we see neutrinos arrive before the photons. Neutrinos get
here first and they tell you watch out a supernova's
coming three hours later. Oh really, it's like an early
(17:48):
warning system, it is. And you can actually sign up
for an early warning emails there instead of neutrino detectors
here on Earth, and you can go to a website
called s News and they will send you an email
when they detect a big flux of neutrinos coming to
the Earth. Oh wow, cool, So that you can run
outside and not look at it, just so you can know.
(18:09):
Man who doesn't want to know, so you can go
down down to your bunker and not look up at
the sky like our president. It might mean that in
three minutes you are that's going to fry. Yeah, it
could be. That would be the first warning. And the
neutrinos get here first because they're the only ones that
can escape the star. Photons, of course, travel faster than
neutrinos because neutrinos are not massless like photons are. But
(18:33):
neutrinos can fly out of the star, whereas the photons
get absorbed inside the star as it's happening, and so
photons don't leave the supernova until like the shock wave
reaches the surface, which is a few hours after the
beginning of the explosion. Yeah, the the the explosion itself. Yeah,
they get sort of reabsorbed, and it takes a little
while for the photons that will reach Earth to be omitted.
(18:54):
So that's why the neutrinos get here first, not because
they're faster, but because they sort of left first and
didn't get socked. All right, Well, let's get into what's
happening here. It's super fun to think about this stuff,
you know, because it's a it's a dramatic event, and
so people really like thinking not just about how stars
form and how they burned, but how they blow up
and what makes it happen. And as far as we know,
(19:15):
there are sort of two totally different kinds of supernovas
that happened. Both of these kinds of supernova reflect this
classic Titanic battle between gravity and fusion. In one case,
fusion winds and in the other case, it's gravity that
comes out on top. The first one we call a
runaway fusion, and the second one is probably better well known,
(19:36):
is the core collapse supernova. But they're really very different
kinds of events. Would you classify them both as supernovas? Like,
it's still a star exploding, it just happens in in
very different ways. Yeah, And there's lots of different categories
of supernovas. You might have heard of type one A,
type two, type two C or whatever those described basically
what they look like in the sky, what the sort
(19:56):
of energy spectrum from them looks like. But there's two
fundamental mech isms, this runaway fusion and this core collapse.
That's cool, Let's let's get into the first one here
runaway fusion. That sounds like um, like an experiment that
got away from you. I thought you were gonna say
it sounds like a physics based romcom movie, Julia Roberts.
So this is what happens when a star. It sort
(20:18):
of has like a resurgence. It's a star that's had
its day and then sort of died, and then it
has a bit of a comeback, really like it had
a nice long life as a regular star, and it
was already waning, but then it rallied at the end precisely,
and it's sort of in retirement and then it sort
of brought back for one last explosion. And so what
(20:40):
happens here is you have a very normal kind of star,
a big star, a red giant. And remember what's happening
inside a star is that gravity is pushing in, it's
squeezing everything, and because of all that pressure, you're getting fusion.
You're turning hydrogen into helium and helium and heavier stuff
and heavier stuff into even heavy your stuff. Right, You're
(21:01):
you're squeezing stuff together so much it's it's burning and
exploding and fusion ng and releasing energy at the same time.
That's right. And you might wonder, like, why doesn't an
object like that immediately collapse into a black hole. And
the reason is that there's outwards pressure and that pressure
comes from the explosions, right, it's burning, that's shooting stuff out.
And also because matter doesn't like to get squeezed that far,
(21:23):
so you know, you squeeze stuff together, it doesn't like
to compress, so there's some pressure back out and that's
what keeps the star alive. Is this balance between gravity
squeezing in and pressure pushing out to keep it alive. Right.
It's kind of like if you're squeezing a bag of
of of corn kernels, like you would squeeze them, but
that would someone would be popping at the same time,
(21:45):
so you wouldn't automatically just collapse or explode. You might
reach this balance, which is a star. I've heard of fusion,
and I've heard of cold fusion, but I've never, until today,
heard of corn fusion. I think you might be a
brand of pop corn. It's a brand of popcorn physics
snacks corn fusions, right, Yeah, there you go. Well, I'm
(22:07):
waiting for candy corn fusion. But that's why I think
that's what you mean. It's like you squeeze something and
then it pops. And so if you have a whole
bunch of that and you're squeezing them, David, some of
them keep popping until you it's hard to sort of
like keep compressing them. I know we're supposed to be
talking about supernovous, but now I'm desperately curious. What would
happen if you actually squeeze that much popcorn? Would they pop?
I bet they would. Bet you'd be heating and pressuring,
(22:28):
and uh yeah, you might get a self sustaining corn reaction.
That's exactly the idea. And what happens inside the stars
that you're fusing the stuff and it's making heavier stuff,
and that heavier stuff can then, if you're big enough,
and if you're hot enough, can also get squeezed and
burned and fused. But as the stuff gets heavier and heavier,
(22:49):
you need higher and higher temperatures to keep the reaction going. Oh,
I see, at some point you sort of run out
of fuel, Right, at some point you can't keep this
up forever. You can't keep it up forever. And for
some kind of stars, the ones we're talking about red giants,
they keep burning until they sort of make carbon, and
it's basically like ash, and so it burns all the fuel,
but it's not big enough to burn carbon, and that's
(23:11):
sort of the end of its life. It's like, Okay,
I'm done. I've burned as far as I could, as
hot as I could. I reached my pinnacle. Now I'm
a big ball of hot carbon. I don't have it
in me to make this carbon fuses. It's just not
big enough. Like if there were more of it right
then there would be enough gravitational pressure to squeeze it,
make it hotter and to ignite that carbon, but there
(23:32):
isn't and so it just sort of stops there, Okay,
and then it sort of cools off. Yeah, and what
you have there or something called a white dwarf, which
is a fascinating object because it's not fusing anymore. It's
just sort of like a big hot lump of carbon,
but it's still glowing. It's glowing because it's super duper hot.
It's literally white hot carbon. It's glowing in the infrared,
are also invisible light. In the visible light, yeah, you
(23:54):
can see white dwarfs, but they're not shining because of fusion.
They're shining because they're just sort of left overheat from
their past life when they were fusing. And my favorite
bit about this is that white dwarfs, because there's no
more energy coming in there, eventually they're cooling off, and
eventually they'll just sort of snuff out and turn into
something called a black dwarf. Oh, I see, if you
(24:16):
it's red hot, it's white hot, and so that's somebody
it can just cool off and it just becomes like
a giant ball of rock. Yeah, but that's never happened
yet in the universe. We estimate that they would take
about ten to the fifteen years, that's how hot this
thing is to cool off. But the universe isn't old
enough for any black dwarfs to exist. So we have
(24:36):
this like category of stars that we haven't sort of
achieved yet, haven't unlocked yet as a universe, like a
like a video game. Yeah, like a video game, like
a video game achievement. I see. So we know what's
going to happen to them, but none, none of none
of them have actually done it. None of them have
actually done it, and some small fraction of them sort
of step off that path, right, So you might be thinking, Okay,
(24:59):
how's this d up in a supernova? Well, what happens
is that some of these guys they think they're at
the end of their career, but then they get a
sudden dose of extra fuel. To say, for example, you're
in a binary star system and you're a white dwarf,
and then the other star starts expanding because it gets
older and you start sucking up some of its material,
or for some other reason, a bunch of new material
(25:20):
comes by and you accrete it and you suck it in.
Is it that little bit of extra energy or you
know gravity, It needs to start cooking that carbon precisely,
and so you get enough extra fuel, right, you get
all this extra stuff, then you can get hot enough
to burn carbon. And what happens then is that it
just goes nuts because it's like volatile, like carbon is volatile. Yeah,
(25:41):
and this is what we call runaway fusion. It's not
like very slowly cooking gently over millions and billions of years.
It's like it burns all that really fast, all at once.
And in the usual star, you know, you have these
shells different temperatures and different densities. You have the heavier
stuff in the middle and the lighter stuff on the outside.
But here you have basically a ball of carbon with
(26:02):
some oxygen in it, and it's just ready to go.
And you deposit enough fuel on that thing and it
will explode like ten to the forty four jewels, all
within just a few seconds. It unbinds the star. It's
really incredible. It really literally like blows up from the
inside here. Fusion wins and gravity just can't keep the
star together anymore. Imagine what would happen if every part
(26:25):
of the Earth suddenly had a huge amount of energy
like it had, It's enough energy to escape the Earth's gravity. Well,
that's what happens to this star, Like every element of
the star now has escape velocity from the star. Gravity
is overcome and it's just like spews itself over the cosmos.
So how does it start. It starts in the middle,
(26:45):
like some of the carbon starts to fuse, and then
that releases energy with it, which then fuses the carbon
in the in the outer layers, and so the whole
thing just suddenly has enough energy to fuse and explode. Yeah,
and you know, this is sort of the simplified model
for what we think might be happening and runaway stars,
and we've seen some of them, and but you know,
(27:06):
it's hard to really know those first moments because again
you can only spot the star after it started to
go superno, but we don't know which white dwarfs are
about to go. So we really haven't seen the very
beginning moments very often, and so it's really difficult to
study until compare our simulations to data because it happens
(27:27):
within a few seconds. Like it's like it would like
be trying to figure out what made a grenade explode
or something, because you know, it just explodes. Yeah, it's
like if you're looking at a huge field of grenades
and you don't know which one is going to explode.
All you can do is like snap your neck around
as soon as one blows, But then you've missed it.
So you never get to see those first moments. And
so you might think, well, why don't we just image
(27:48):
all the stars all the time, And yeah, I'd love
to do that, right, that would be a great strategy.
Just as just as signed some grad students to each
star in the in the universe, how many grad students
do we have, and we do have have some really
big survey missions UM that scanned the whole sky and
try to spot these things. But again, you can only
notice them, you know, after they happen. We'd love to
(28:08):
study them just before they happen, so we can see
what's causing it, right, because I guess we UM. I mean,
they do surveys of the sky that they're always looking
at stars, but to get enough of information from the
one that blew up is hard because you have to
sort of focus on it. Yeah, and you'd love to
use our most powerful telescopes. And we have sort of
two kinds of telescopes. Ones that are really broad they
(28:30):
can image the whole night sky, but they're not that powerful,
and ones that can look really deeply at one object,
like the hubble, you know, but it can't really scan
the whole night sky because it's it has to point
really carefully at one thing. I see. So even with
the early warning system of the neutrinos, we can't that
won't tell us which star is gonna blow. That's what
(28:51):
we try to do. We try to see the neutrinos
and then like whip stuff around. But you know, neutrinos
are hard to spot because even a gazillion of them
will come through the Earth and not interact. And you know,
new tunion detectors are sometimes busy doing other things, are
not dedicated to supernova's. They try to hook these things up,
and when the neutrinos tell us the superno is coming,
they point in that direction. And so we do our best,
(29:12):
because remember, the supernovas have taught us a lot about
the universe. They're the ones that gave us the clue
that the universe is expanding. All right, So that that's
the first way that a star can goes supernova is
it's happily retired, but then it gets something triggers it,
and it just goes out in a blaze of glory,
runaway blaze of glory. That's right. It was saving up
(29:34):
for one last hurrah. All right, Let's get into the
second way in which supernose can happen, But first let's
take a quick break, al right, Daniel. So the second
(29:54):
way that uh supernova can happen is called core collapse.
And I think this is maybe the one that most
peop we're familiar with. Why why is this one? More?
I guess popular this is the case where gravity wins
in the epics struggle with fusion. I think this one's
maybe more awesome. I mean, I don't mean anything negative
about runaway fusion the size of a star glowing five
(30:15):
billion times brighter than the sun. But this one involves
implosion and explosion, so maybe it's like double awesome. Okay,
so there's some implosion involved in this one, right, I
guess it's in the word core collapse. Yeah. So in
this scenario, again, you start as a really big star.
You've gotta be our big enough star to even consider
going supernova, like a star like our Sun is never
(30:36):
going to go supernova. Hey, that's good to know, and
be what do you mean big? Like, what's the threshold
for supernova? Is it like many times the size of
our sun or a little bit more. It's like five
to eight times in the mass of the Sun is
like the bare minimum you need to have a supernova.
Beyond that, you can't even get an agent to return
your phone. Yeah, you're forever be list which I think
(30:59):
is a good thing. But this sort of core collapse
superno requires a really big star. And we were talking
earlier about what's happening inside the stars. You have this
fusion and you're creating heavier and heavier stuff. Well, in
some stars they are big enough to fuse carbon, and
then they fuse the byproducts of carbon and make heavier stuff,
and the byproduct of that make even heavier stuff. So
(31:20):
it's a bigger factory, and it goes beyond what these
other stars that we talked about can do. They can
actually fuse carbon and and uh and make heavier and
heavier elements. But it's sort of a more controlled process
because it's happening gradually. It's like an equilibrium. Stuff is
slashing back and forth, and the carbon fuses and turns
into the next thing. And these guys confuse all the
(31:41):
way up to iron. Remember that up to iron, when
you have fusion, you release energy. Above iron or nickel
or so when you fuse it absorbs energy and so
it would cool the star down. So like what comes
right before iron. Yes, so iron is number twenty six
and nicholas, and that's about as high as you can go.
I mean below that you have oxygen at eight you
(32:03):
can make you make magnesium a twelve aluminum silicon. Anything
below iron, when you fuse it together, releases energy so
that that sustains the explosion of the star. But you're saying,
after iron, if I want to fuse more things, I
have to sink energy into it. Yeah, and so it
actually sucks energy out of the star. It starts to
(32:25):
cool it. And this is the enemy of the star.
The star remembers trying to well, it doesn't like feel
anything or want anything. But if a star is going
to continue to burn, it needs to exert outward pressure
against gravity. But it's sort of working against itself because
it's making heavier and heavier stuffed. And so you know,
as it's making heavier and heavier stuff, it's making the
(32:46):
gravity stronger and more powerful because it's getting denser at
its core. And so if you're then also cooling down
your own reaction, then you're fighting against yourself. Wow. So
and eventually what happens. It winds like you run out
of things to fuse. Everything's iron, and then gravity wins. Yeah,
eventually gravity wins and it pulls itself together and it
(33:10):
collapses and gravity says, all right, I'm blowing past you.
And there's this point it's called the Chandra Shaker limit.
It's essentially when matter cannot be squeezed anymore. Let's see
when all the electrons are pushed down into their lowest orbitals,
and everything is tucked as close as possible, and that's
what like a white dwarf for a neutron star is
(33:30):
sitting at. But when gravity has enough power to overcome that,
that electron degenerously. When you have too much stuff, then
it collapses and gravity takes over, meaning that um, whatever
is keeping the star kind of fluffy, it's no longer enough.
Burned too much, and now it's it's too heavy. Yeah,
there's not enough outwards pressure and there's growing gravitational pressure inwards,
(33:54):
and so eventually gravity just overwhelms it, and that's when
you get this core collapse. I guess collapse means that
it it's just sort of like folds folds in or
what does that mean? Like all the Adams were happy
sort of bunched together, but now they crunched in together more. Yeah,
and you actually get an inwards going shock wave. And
so people sometimes talk about supernovas as implosions and that's why,
(34:16):
because you get this shock wave of stuff rushing in
towards the center. Wow, because the in the innerts of
the star are I guess collapsing before they were sort
of fluffy from all the energy. But now they're just
they're out of energy, so that everything's just crunching together.
To think about the surface of the star, what's happening
there is it's constantly getting pulled in by all the
(34:38):
heavy stuff inside the star, and it's getting pushed out
by the burning. Eventually, if the burning is not strong enough,
you know, if it passes this limit, then that stuff
gets pulled in and it compresses the next layer, which
compresses the next layer, which compresses the next layer. And
it's a runaway process because the more you compress something,
the higher density it is, the stronger the gravitational force, right,
(35:00):
because as you get closer, the gravity stronger. Yeah, so
the whole thing just it just falls inwards. It falls inwards,
and then what happens depends on how much stuff you
started with. And if you're like super duper big, like
more than forty times the mass of our Sun, then
that's basically it. You just collapse into a black hole
without even making a peep. The star just kind of
(35:22):
bloop turns into a black hole. Yeah, you can just
go and suck itself into a black hole without a supernova,
like you can skip the supernova stuff. If you're big, Okay,
so that's if you're really big. If you're really big,
But if you're not big enough, then the core collapse
sort of goes inwards and then it bounces off the hot,
dense core of the start, like the shock wave comes
(35:43):
in and it reaches a point where the stuff is
so dense that it can reflect that shock wave back out,
and that's when the supernova happens. That's when like stuff
flies out from the star. Oh, it's all this energy
of stuff falling in. It's the balance. That's actually the explode. Yes,
it's the bounce. And if you're too big, you don't
get the bounce, right because it just like turns into
(36:05):
a black hole and then nothing can escape. But if
you're if you're below that, if you're like around thirty
times the mass of the Sun, then you get a
bounce that goes out with a supernova and the core
becomes a black hole. Oh really, only the core that
the other stuff bounces away. Yeah, you get the supernova,
this huge shock you know, expus plasma through the universe
(36:26):
and neutrinos and light and energy, but the core of
it remains and becomes a black hole, and that's different
than the other kind of runaway fusion, which didn't form
a black hole. That's right, Those don't usually form a
black hole. Sometimes those can end with a really dense
neutron star, but a lot of times it's just blowing
out most of the mass of the star in the
runaway fusion. In this case, if you're more than forty
(36:47):
times the mass of the Sun, you go straight to
black hole. If you're more than thirty times the mass
of the Sun, you've got a huge supernova when the
bounce turns around and you get a black hole the core.
If you're a little smaller than that, it's the same story.
Things bounce off the center and then explode down to
a supernova, but instead of a black hole the center,
and you get a neutron star, which is like a
(37:09):
really dense massive material, but not quite dense enough to
form a black hole. I see you just you just
become a like a compact star. Yes, you just become
a really compact blob. And then there's a little window
between like seven and ten times the mass of our
Sun where um when the gravitational collapse happens. Then it
(37:29):
causes runaway fusion and the whole thing just blows um
in a huge explosion. So there's all these like pockets
like if you're this big, then you'll go supernova if
you but if you're a little bit smaller you won't.
But then if you're a little bit smaller still you will.
Like we said, the fate of the star depends almost
entirely on its mass, and so there these little windows
(37:49):
like if you're in this window, this happens. If you're
in this window, that happens. It's like, oh, man, I
shouldn't have eaten that last planet now, now now I'm
gonna explode. Literally. Wow, that's interesting. But again, sort of
the common thing about all of these scenarios is that
it's the it's a collapsing star that becomes a supernova, right,
(38:09):
And sometimes it's at the bound. Sometimes it's just it
creates a runaway explosion. Yea. For all these core collapse
they start with really big stars have been big enough
to burn a lot of heavy stuff to go past
the carbon limit and uh, and then to pass this
gender's say, card limit and collapse gravitationally, right, and then
a couple of different things might happen after that. To
(38:32):
be a supernova or not. Yeah, you could be black hole.
You can be black hole plus supernova. You can be
just supernova. You could have as a neutron star. There's
lots of different options there, all right, So I guess
the next question is should we worry about supernova? Is Daniel,
is this something that might happen like with three minute warning,
we'll find out that the star next to us is
going supernova and then and then goodbye Planet Earth? Or
(38:55):
is it unlikely to happen around us? Well, we sort
of trying to calculate two different things. One is how
close would a supernova have to be to be dangerous?
And they figured that if ones within like twenty five
light years or so, it would basically destroy half of
the Earth's ozone layer, because the half that's facing that
star would be fried. And that would be bad because
we'd be suddenly like totally exposed to space. An amount
(39:17):
of X rays deposited on the planet would like sterilize
half the population and or give them cancer instant, Oh
my god, within minutes or within days or very quickly. Yeah,
I mean, does it really matter if it takes days
or minutes to get cancer? You've got cancer. Well, but
everything else would stay the same, like a solar system
would still be here and we'd be going around the
same orbit. Yeah, and you know, that's an interesting question.
(39:38):
People wonder if there are gravitational waves from supernova, but
we've never seen one before. But it wouldn't affect like
the gravity of the Earth. We'd still be orbiting the
Sun the same way. Would just be like you know,
mostly toast. But fortunately, we've looked around and we haven't
spotted anything that we think is going to go supernova,
anything anywhere within the nearest five light years. Now, again,
(39:59):
we don't have a great understanding of when a stargo supernova,
but we think we have a sense for the which
kind of star can go supernova, and we don't see
any of those nearby. And you know, supernovas are not
just bad news, right, supernova is they're sort of part
of the life cycle of the galaxy. You know how
we learned that forest fires aren't all bad because they
helped like clean out dead wood and provide space for
(40:22):
new animals. You know, well, they're good as long as
you don't live in your house is not next to you. Yeah,
exactly that way. It's a sign of a healthy forest
to have occasional small fires. In the same way it's
a sign of a healthy galaxy to occasionally, know, clear
out some of the clutter in the dust and blow
up the old stuff and make room for something new.
Because that is kind of how um heavier materials like
(40:44):
we wouldn't be you and I wouldn't be here if
if it's not for a supernova, and it's not just
the supernova throw that stuff out into the universe. That
is true. But also we wonder about like what makes
a star begin, Like give a big cloud of gas
and dust. Is gravity just like very gradually pulling it
together over billions of years. Some people think that it's
(41:05):
the shock wave from a nearby supernova that sort of
triggers that gravitational collapse of that cloud into a star.
So it might be that the death of a star
the supernova is what you need to form new stars.
Stars begetting stars. It's all cycle, man, it's the circle
of life. Somebody que Elton John, But who who made
(41:26):
the first star? Then, Daniel, what came for as the
star or the supernova? The eternal question? I believe that
one for the philosopher's all right, well, I feel like
I learned a lot about supernovas today. You know, I
thought that they only did the supernova through core collapse.
They didn't know that there were all these other ways
that they can happen. Yeah, supernovura fascinating and we're constantly
(41:46):
studying them because they are dramatic and they're awesome to
learn about, and because we'd like to know, you know,
what happens at the end of life of a star.
It's it's fascinating, it's dramatic, but it's also still mysterious. Yeah,
and it's a big part of how the universe works, right,
like how you make metals and everything all around this,
everything around us is was basically made in a supernova.
(42:08):
Would you say that, like all the metal and components
in your phone, in your car, that all came from
a supernova. All that stuff was fused inside a hot
star billions of years ago. Yes. All right, Well, we
hope you enjoyed that. And the next time you look
up at the night sky and see something getting brighter,
duck or at least close your eyes. At least close
(42:29):
your eyes and look it up online later. All right,
thanks for joining us, See you next time. Before you
still have a question after listening to all these explanations,
please drop us a line. We'd love to hear from you.
You can find us on Facebook, Twitter, and Instagram at
(42:52):
Daniel and Jorge That's one Word, or email us at
Feedback at Daniel and Jorge dot com. Thanks for listening,
and remember that Daniel and Jorge Explain the Universe is
a production of I Heart Radio. For more podcast from
my heart Radio, visit the I heart Radio Apple Podcasts,
or wherever you listen to your favorite shows. Yeah,
Hey, Daniel, do you like looking for shooting stars? I
do because sometimes the nice sky is really static, it
seems frozen, and so it's exciting to see something streak
and flame out across the sky. You know they aren't
really stars, right, Um? I am aware, thank you very much.
I also know that nobody's actually shooting those stars as
(00:29):
far as we know. You know aliens. Hello, you're going
to hit the aliens button before me. But it would
be cool to actually see a star explode, you know
what I mean. You're looking at at the sky and
suddenly one of them just goes Yeah, as long as
it's not our star, would be pretty fun to watch.
(01:04):
Hi am poor handmade cartoonists and the creator of PhD comics. Hi.
I'm Daniel Whitson. I'm a particle physicist, and I'm the
co author of the book We Have No Idea, A
Guide to the Unknown Universe, book about all the things
we don't know about the universe. And you wrote it
with a really awesome and fun cartoonist, didn't you? I did,
in fact, and I was recently contacted by one of
(01:27):
our listeners and one of our readers in the Czech Republic,
who's reading our book in check, I hope it says
the same things. It doesn't English. Well, he actually told
me how to translate the title in check literally into English.
But how does it translate. Apparently it translates to we
don't even know fart about it. Really, the word fart,
(01:47):
isn't it? He says. It's a very common expression in
check for I don't know fart about that, and that's
the expression they chose for the title in check. Wow.
I wonder if we had named that, made that the
actual title in English, maybe we would assault, we would
dislike more copies. I don't know. Maybe the book would
kind of stink. But it's a really fun book. It's
all about the unanswered questions of the universe, all the
(02:09):
things we'd like to know about our lives and where
and where we live and how the universe began but
don't yet know. And so we hope on this podcast
to take you on a tour of what we do
and don't know about the universe, and maybe one of
you out there, a young budding scientist, will be the
one to figure out the answers. That's right. We bring
to you all the amazing mysteries of the universe, and
all the farts in the universe and all the mysterious
(02:31):
farts in the US parts, the ones that fortunately you
can't smell through this audio podcast. Well, welcome to Daniel
and Jorge Explain the Universe, a production of I Heart
Radio in which we examine them the amazing, the mysterious,
all the weird and wonderful things in our bonkers universe,
and we talk about them in a way we hope
entertains you and also teaches you something deep about the
physics of our universe. Yeah, we talked about all the
(02:55):
sort of a nice and beautiful and wonderful, inspiring things
that are out there in universe, the big and the small,
but we also talk about some of the crazy things
that happened. That's right, because the universe is dramatic and
it is violent, and when it wants to make a splash,
it goes big, it goes supernova, it goes hyper nova, hypernova. Yeah,
(03:16):
So to be on the program, we'll be tackling perhaps
one of the most um I don't know, violent or
you know, dramatic or you know, maybe interesting events that
happened out in the universe. And that happens quite a bit.
That's right. It's one of the most interesting and dramatic
things that can happen in our universe. One of the
things we've seen, the kind of thing that we can
(03:37):
even find in historical records that people in ancient times
noticed happening in the sky and wondered what it was
all about? Right, and then so the question is how
much do we know about it? How much do we
understand about this incredible event and what we can do
if one happens near us? Yeah, and the answer is
basically dig a hole and pray. All right, let's get
(04:00):
into that. So to be on the podcast will be
asking the question what makes a supernova blow explode? I
guess super what makes a supernova explode? Or what makes
a supernova a supernova? What makes a supernova so super? Yeah? Yeah,
(04:21):
why isn't it a super dupernova? Or well, you know,
the name nova is actually quite fascinating. It means new
and so super. So supernova is like something super and
new in the sky. It comes from people looking at
the sky and saying, hey, that wasn't there before, or
that's different, and it's pretty rare to see something change
in the sky. I mean, we're used to the patterns
(04:42):
of the seasons and the days and the nights and
all that stuff. But otherwise the stars, you know, their
lifespan is much longer than ours, and so to see
one dies pretty unusual. We'll be talking talking about supernovas
and what how what causes a supernova and how that works.
But it's basically the biggest explode shin you can have
in space? Right? Is that true? The whole universe? That's
(05:04):
the biggest explosion that happens. It's the biggest explosion we've
seen so far. I mean, the stars are one of
the biggest things out there. I guess you can imagine
a galaxy exploding, but it's hard to see how that
would happen. A galaxy nova. Nobody's ever seen that yet.
What would you call that an uber nova or over nova?
(05:25):
But I guess maybe it's the biggest explosion because you know,
stars are some of the most you know, energy pack
things out there, right, I mean that that can explode
like you don't see a black hole exploding. You don't
yet see black holes exploding. That would be fascinating. And yeah,
the key to having a big explosion is not just
being massive, having a lot of energy, but releasing it
(05:46):
very very rapidly. Right, That's basically what an explosion is.
It's like it's like a bomb. You want to deposit
a lot of energy and you want to do really quickly,
so you got a shock wave of action. And that's
the thing that makes supernova is exciting that they happen ly.
It also is the thing that makes them hard to
understand and hard to spot because we don't know it
precisely what causes the star to go supernova, and they
(06:08):
don't happen that often, so it's pretty rare to see
one's start to go oh wow. Really, we don't know
what cosses these supernovas. No, we have some general sense
for what happens during the supernova, and we'll dig into
it on today's podcast. But what makes it go now
and not next week. To predict when an individual star
will go supernova is not something we know how to do.
(06:29):
Nobody's pressing a switch that you can see. Yeah, they
don't annow it's a big countdown like NASA. You know,
t's not taking time bomb. No, and astronomers would love
to see a star like five seconds before superno, one
second before supernova the first moments, you know, that would
be fascinating, so you can catch it as it as
(06:49):
it's happening. Yeah, And there's actually a guy who was
watching the skies in two thousand and sixteen, an astronomer,
an amateur astronomer. He was just happen to be looking
at one star her through his telescope and he saw
it go supernova, like in real time. Wow. What are
the chances of that? Well, they're pretty low because it's
actually not that many stars that will go supernova, Like,
(07:10):
not every star ends up in a supernova. And of
course stars lived for a really long long time, and
so they calculated the odds is like one in ten
million or one in a hundred million that if you're
looking at a star or through a telescope, that you'll
be watching it go supernova. Oh. So this person was
looking at the star through his telescope or her telescope
and it went supernova as he was looking at it.
(07:31):
As he was looking at it. Now, of course this
time delay went supernova a long long time ago, but
the images from that supernova arrived on Earth as his
eyeballs were pointed at it. Oh wow, And so how
did he prove this. Did he have a about his
cell phone and took a picture of it? Yea, all
good amateur astronomers have cameras attached to their telescopes, so
(07:53):
he snapped some photos. Then, of course he alerted astronomers
who all pointed their telescopes at it to try to
catch a glimpse of the first moment to the star
going nova. What is that true? He actually took pictures
of it? Oh yeah, Oh wow, that's pretty interesting. Wow.
And so supernovas are sort of famous, like people have
heard of them. People know that they're a thing. They're
pretty dramatic. Their pr campaigns have been pretty good. Yeah,
(08:15):
they're there's sort of in the general consciousness for sure,
of I think culture and society. I mean, everyone knows
him as his stars exploding. Yeah, but I was curious,
you know, how much did people actually know about a supernova?
Did they know what really happens inside? Do they know
what causes it? Do they know whether we understand supernovas?
So I walked around campus here at you see Irvine,
(08:35):
and I asked folks what they knew about supernovas. Yeah,
so think about it for a second. You've probably heard
of supernovas, But do you know what causes them and
how they actually explode? Here's what people had to say.
I guess it's something to do with the star exploding.
When a star explodes, What makes it happened? Um, the
death of the star. Supernovas usually like an exploding star, right,
(09:00):
so what makes its age? Are you going to explode
when you get over? Who knows? I know that supermanovas
are when a star reaches the end of its life
and eventually the force of gravity overcomes the push from
the inside of the star and it collapses and then explodes.
I know they're in space and it's is it? Is
(09:21):
it when a star like implodes or something more? I
know that they are the final stage and stars. Okay,
what makes it happen? Eventually, the the it becomes too dense,
the elements that it creates in the in the middle.
At that point it collapses in on itself. And there's
a few things that can happen. But a supernova is
one of them. A supernova No, I don't alright? Cool,
(09:45):
So I think it sounds like everyone knows what it means,
Like it means the death or the explosion of a star. Yeah,
they knew that it marks the end of the life
of a star, but a few people have really a
sense for like what's going on inside the supernova? What
makes it happen? Why do stars die that way? Why
do stars die at all? Why don't they just burn forever?
So it's a big e explosion in space. And you're
(10:07):
saying it's rare, so only about one to three supernova's
per century or something like that in a typical galaxy. Yeah,
we have seen a lot of supernovas from Earth, but
almost all of them have been in other galaxies. And
that's because most stars will not go supernova. In a
galaxy like the Milky Way that has about a hundred
billion stars, only about one or two, maybe three will
(10:30):
go supernova in a hundred years. So it's not it's
pretty rare. Most stars don't go supernova. Most stars do
not go supernova. The fact that we've seen hundreds is
only because there are so many stars and so many
galaxies out there. But you know, we're lucky and we're
glad actually that they're not a lot of supernovas, because
they're pretty devastating. Oh I see, So if a supernova
(10:53):
goes off in a galaxy far away, we'll will actually
see it, like it'll outshine the whole galaxy and we'll
see it, uh, you know, take over the light from
the galaxy. That's right. It's a really dramatic event. It
can be as bright as the entire sum of all
the light from the rest of the stars in the galaxy.
And so it's like it like doubles the brightness of
(11:13):
a galaxy when it happens. And the most amazing thing
is that most of the energy from the supernova doesn't
even come out in the form of light, so you're
seeing a tiny fraction of this incredible explosion in the
visual spectrum. So if you see if you're looking at
a galaxy at any point and you see it certainly
bright up, it's because of a supernova inside of it,
like one of its hundred billion stars went boom. Yeah, precisely. Well,
(11:37):
let's get into it, Daniel, all right, um, and explain.
Let's explain to people what a supernova is. I guess
what's the technical definition of a supernova. Yeah, so technically
a supernova is the end of the life of some
kinds of stars. Now not all stars. In fact, most
stars will not go supernova. But it's essentially the star
explodes and it sends out most of the energy that's
(12:00):
stored inside of it out into space in the form
of electromagnetic radiation, so visible light, which is a tiny fraction,
and an enormous number of neutrinos, just like gobs and
gobs and gobs of neutrinos, and then also an enormous
amount of matter. This is like shock wave of just
stuff that gets spewed across the universe, like the shrapnel
(12:21):
and the grenade. Yeah, like the shrapnel and the grenade.
And it's good that that happens because that goes out
and that seeds other stars to form, and it spreads
the heavy metals that were burned inside that star out
into the universe, so you can get interesting things like
a rocky planets then life on them. Well that's interesting.
So it's not Supernova is not like an accident that
happens to a star. It thought like um, a star
(12:43):
is suddenly gets out of balance. It's like it's like
in the DNA of the star. You know, like once
you once you know what kind of story you are,
you will most likely go supernova or if you know
the kind of star you know you'll never get you'll
never go supernova. Yeah, it's sort of like that, and
it's not totally under good, but it's something like if
you know how much master is to a star and
(13:04):
you know what it's made out of, Like did it
start just from burning hydrogen because you're one of the
first stars in the universe, or do you already collect
the burning remnants of other dead stars and so you
have helium and oxygen and nitrogen and carbon and all
that stuff already. If you know that starting point, you
can almost always predict the life cycle of a star,
including whether it's going to become a black hole or
(13:26):
a neutron star, or goes supernova, become a white dwarf
or whatever. That's basically what determines it is like how
big a scoop of stuff did you get of the universe?
And what's in that scoop? Wow? And that the terms
your your whole life cycle. If you're a star, like
you're born and everyone already knows how you're gonna die.
Here's a baby. Oh, this baby is going to be
a rock star and it's going to you know, shine brightly,
(13:50):
but then it's going to go out in a blaze
of glory when he or sheet turns thirty two. Stars
are not nearly as exciting and variable as people are. Right.
They're much bigger, and they're much more dramatic, but they're
also simpler, and also they don't really interact with each other.
Like a star is pretty isolated. It's got its own
little pocket of stuff and it just sits there and
burns it until it can't burn it anymore. We know
(14:12):
it's gonna go supernova, but you can't predict when it's
going to go supernova. Yeah, these stars have some something
of a variable lifetime, and you know these events, the
supernov event happens really quickly. Remember that the like the
time scale for stars can be millions and billions of years,
but the supernova events, the time scale for that is
days and so days, days, and so it happens really quickly,
(14:35):
especially the first bit the explosion. We're talking seconds and minutes,
and so what triggers that to happen? Is it like
a clock that ticking down. Eventually it's just gonna happen
like that. You could predict it a million or a
billion years in advance, if you knew well enough. What
was happening inside the star or is there some like
quantum mechanical randomness that's happening, or is it triggered by
(14:55):
some external event, like the star becomes really fragile and
then you know, a path seeing shock away from something
else makes it go. We just don't really understand those
moments or you know, um like a planet falls into
it and that triggers it. Perhaps, Yeah, there are stars
like that that do get triggers from in falling material,
but we don't know exactly like when that happens. All right, well,
(15:17):
let's get into the mystery of what triggers supernovas and
what's actually happening when they explode. But first let's take
a quick break. Right, So we we've seen a couple
(15:39):
of these supernovas in the night sky, like without telescopes. Right,
there's a historical record of supernovas and in humanity's history. Yeah,
it's a big event in the night sky when something blows.
And back before people really understood what stars were, they
were still interested in looking at them and commenting about them.
And so you can go back in the historical record
(15:59):
and can find ancient astronomers writing about this and the
earliest one. It's called h B nine is from b
C and we see this an ancient ancient texts. They
talk about the appearance of a new star in the sky.
So they just called it HB nine. What were those
ancient people thinking they had acronyms and numbers for I
(16:20):
don't know, we don't know who was We know it
was some unnamed Indian astronomers. We call it h B nine.
But you know they wrote about it as a as
a new object in the sky. Well, what would we
see if if I happened to be looking at the
nice guy and a Superno, what just happened to you know,
occur while I'm looking at this guy? What would I see?
Would I see a star suddenly grow bright and fill
(16:42):
the sky with light? Or would just would it just
be a star that gets a little bit brighter. Well,
it depends on how close it is. Of course, the
star is gonna get millions and millions or even billions
of times brighter than it normally is. Like, would it
be dangerous to look at it? Yes, if you are
looking at a star that's going supernova in our galaxy,
it could be very dangerous. I mean, you could fry
(17:04):
all life on Earth. That's kind of dangerous. So yes,
looking at it would be bad, all right, Um, and
then what would would I see it go bright for
like a few seconds, for a few hours, for a
few days. So the light curve of a supernova looks
like very rapidly getting brighter and brighter over the period
of a few days and then gradually fading over the
(17:25):
period of a few weeks outter a few months. So
it wouldn't be like a sudden flash. You would get
a little bit of warning. You would get brighter and
brighter and brighter over a couple of days. Yeah, And
you can actually get a warning before the flash arrives
because we see neutrinos arrive before the photons. Neutrinos get
here first and they tell you watch out a supernova's
coming three hours later. Oh really, it's like an early
(17:48):
warning system, it is. And you can actually sign up
for an early warning emails there instead of neutrino detectors
here on Earth, and you can go to a website
called s News and they will send you an email
when they detect a big flux of neutrinos coming to
the Earth. Oh wow, cool, So that you can run
outside and not look at it, just so you can know.
(18:09):
Man who doesn't want to know, so you can go
down down to your bunker and not look up at
the sky like our president. It might mean that in
three minutes you are that's going to fry. Yeah, it
could be. That would be the first warning. And the
neutrinos get here first because they're the only ones that
can escape the star. Photons, of course, travel faster than
neutrinos because neutrinos are not massless like photons are. But
(18:33):
neutrinos can fly out of the star, whereas the photons
get absorbed inside the star as it's happening, and so
photons don't leave the supernova until like the shock wave
reaches the surface, which is a few hours after the
beginning of the explosion. Yeah, the the the explosion itself. Yeah,
they get sort of reabsorbed, and it takes a little
while for the photons that will reach Earth to be omitted.
(18:54):
So that's why the neutrinos get here first, not because
they're faster, but because they sort of left first and
didn't get socked. All right, Well, let's get into what's
happening here. It's super fun to think about this stuff,
you know, because it's a it's a dramatic event, and
so people really like thinking not just about how stars
form and how they burned, but how they blow up
and what makes it happen. And as far as we know,
(19:15):
there are sort of two totally different kinds of supernovas
that happened. Both of these kinds of supernova reflect this
classic Titanic battle between gravity and fusion. In one case,
fusion winds and in the other case, it's gravity that
comes out on top. The first one we call a
runaway fusion, and the second one is probably better well known,
(19:36):
is the core collapse supernova. But they're really very different
kinds of events. Would you classify them both as supernovas? Like,
it's still a star exploding, it just happens in in
very different ways. Yeah, And there's lots of different categories
of supernovas. You might have heard of type one A,
type two, type two C or whatever those described basically
what they look like in the sky, what the sort
(19:56):
of energy spectrum from them looks like. But there's two
fundamental mech isms, this runaway fusion and this core collapse.
That's cool, Let's let's get into the first one here
runaway fusion. That sounds like um, like an experiment that
got away from you. I thought you were gonna say
it sounds like a physics based romcom movie, Julia Roberts.
So this is what happens when a star. It sort
(20:18):
of has like a resurgence. It's a star that's had
its day and then sort of died, and then it
has a bit of a comeback, really like it had
a nice long life as a regular star, and it
was already waning, but then it rallied at the end precisely,
and it's sort of in retirement and then it sort
of brought back for one last explosion. And so what
(20:40):
happens here is you have a very normal kind of star,
a big star, a red giant. And remember what's happening
inside a star is that gravity is pushing in, it's
squeezing everything, and because of all that pressure, you're getting fusion.
You're turning hydrogen into helium and helium and heavier stuff
and heavier stuff into even heavy your stuff. Right, You're
(21:01):
you're squeezing stuff together so much it's it's burning and
exploding and fusion ng and releasing energy at the same time.
That's right. And you might wonder, like, why doesn't an
object like that immediately collapse into a black hole. And
the reason is that there's outwards pressure and that pressure
comes from the explosions, right, it's burning, that's shooting stuff out.
And also because matter doesn't like to get squeezed that far,
(21:23):
so you know, you squeeze stuff together, it doesn't like
to compress, so there's some pressure back out and that's
what keeps the star alive. Is this balance between gravity
squeezing in and pressure pushing out to keep it alive. Right.
It's kind of like if you're squeezing a bag of
of of corn kernels, like you would squeeze them, but
that would someone would be popping at the same time,
(21:45):
so you wouldn't automatically just collapse or explode. You might
reach this balance, which is a star. I've heard of fusion,
and I've heard of cold fusion, but I've never, until today,
heard of corn fusion. I think you might be a
brand of pop corn. It's a brand of popcorn physics
snacks corn fusions, right, Yeah, there you go. Well, I'm
(22:07):
waiting for candy corn fusion. But that's why I think
that's what you mean. It's like you squeeze something and
then it pops. And so if you have a whole
bunch of that and you're squeezing them, David, some of
them keep popping until you it's hard to sort of
like keep compressing them. I know we're supposed to be
talking about supernovous, but now I'm desperately curious. What would
happen if you actually squeeze that much popcorn? Would they pop?
I bet they would. Bet you'd be heating and pressuring,
(22:28):
and uh yeah, you might get a self sustaining corn reaction.
That's exactly the idea. And what happens inside the stars
that you're fusing the stuff and it's making heavier stuff,
and that heavier stuff can then, if you're big enough,
and if you're hot enough, can also get squeezed and
burned and fused. But as the stuff gets heavier and heavier,
(22:49):
you need higher and higher temperatures to keep the reaction going. Oh,
I see, at some point you sort of run out
of fuel, Right, at some point you can't keep this
up forever. You can't keep it up forever. And for
some kind of stars, the ones we're talking about red giants,
they keep burning until they sort of make carbon, and
it's basically like ash, and so it burns all the fuel,
but it's not big enough to burn carbon, and that's
(23:11):
sort of the end of its life. It's like, Okay,
I'm done. I've burned as far as I could, as
hot as I could. I reached my pinnacle. Now I'm
a big ball of hot carbon. I don't have it
in me to make this carbon fuses. It's just not
big enough. Like if there were more of it right
then there would be enough gravitational pressure to squeeze it,
make it hotter and to ignite that carbon, but there
(23:32):
isn't and so it just sort of stops there, Okay,
and then it sort of cools off. Yeah, and what
you have there or something called a white dwarf, which
is a fascinating object because it's not fusing anymore. It's
just sort of like a big hot lump of carbon,
but it's still glowing. It's glowing because it's super duper hot.
It's literally white hot carbon. It's glowing in the infrared,
are also invisible light. In the visible light, yeah, you
(23:54):
can see white dwarfs, but they're not shining because of fusion.
They're shining because they're just sort of left overheat from
their past life when they were fusing. And my favorite
bit about this is that white dwarfs, because there's no
more energy coming in there, eventually they're cooling off, and
eventually they'll just sort of snuff out and turn into
something called a black dwarf. Oh, I see, if you
(24:16):
it's red hot, it's white hot, and so that's somebody
it can just cool off and it just becomes like
a giant ball of rock. Yeah, but that's never happened
yet in the universe. We estimate that they would take
about ten to the fifteen years, that's how hot this
thing is to cool off. But the universe isn't old
enough for any black dwarfs to exist. So we have
(24:36):
this like category of stars that we haven't sort of
achieved yet, haven't unlocked yet as a universe, like a
like a video game. Yeah, like a video game, like
a video game achievement. I see. So we know what's
going to happen to them, but none, none of none
of them have actually done it. None of them have
actually done it, and some small fraction of them sort
of step off that path, right, So you might be thinking, Okay,
(24:59):
how's this d up in a supernova? Well, what happens
is that some of these guys they think they're at
the end of their career, but then they get a
sudden dose of extra fuel. To say, for example, you're
in a binary star system and you're a white dwarf,
and then the other star starts expanding because it gets
older and you start sucking up some of its material,
or for some other reason, a bunch of new material
(25:20):
comes by and you accrete it and you suck it in.
Is it that little bit of extra energy or you
know gravity, It needs to start cooking that carbon precisely,
and so you get enough extra fuel, right, you get
all this extra stuff, then you can get hot enough
to burn carbon. And what happens then is that it
just goes nuts because it's like volatile, like carbon is volatile. Yeah,
(25:41):
and this is what we call runaway fusion. It's not
like very slowly cooking gently over millions and billions of years.
It's like it burns all that really fast, all at once.
And in the usual star, you know, you have these
shells different temperatures and different densities. You have the heavier
stuff in the middle and the lighter stuff on the outside.
But here you have basically a ball of carbon with
(26:02):
some oxygen in it, and it's just ready to go.
And you deposit enough fuel on that thing and it
will explode like ten to the forty four jewels, all
within just a few seconds. It unbinds the star. It's
really incredible. It really literally like blows up from the
inside here. Fusion wins and gravity just can't keep the
star together anymore. Imagine what would happen if every part
(26:25):
of the Earth suddenly had a huge amount of energy
like it had, It's enough energy to escape the Earth's gravity. Well,
that's what happens to this star, Like every element of
the star now has escape velocity from the star. Gravity
is overcome and it's just like spews itself over the cosmos.
So how does it start. It starts in the middle,
(26:45):
like some of the carbon starts to fuse, and then
that releases energy with it, which then fuses the carbon
in the in the outer layers, and so the whole
thing just suddenly has enough energy to fuse and explode. Yeah,
and you know, this is sort of the simplified model
for what we think might be happening and runaway stars,
and we've seen some of them, and but you know,
(27:06):
it's hard to really know those first moments because again
you can only spot the star after it started to
go superno, but we don't know which white dwarfs are
about to go. So we really haven't seen the very
beginning moments very often, and so it's really difficult to
study until compare our simulations to data because it happens
(27:27):
within a few seconds. Like it's like it would like
be trying to figure out what made a grenade explode
or something, because you know, it just explodes. Yeah, it's
like if you're looking at a huge field of grenades
and you don't know which one is going to explode.
All you can do is like snap your neck around
as soon as one blows, But then you've missed it.
So you never get to see those first moments. And
so you might think, well, why don't we just image
(27:48):
all the stars all the time, And yeah, I'd love
to do that, right, that would be a great strategy.
Just as just as signed some grad students to each
star in the in the universe, how many grad students
do we have, and we do have have some really
big survey missions UM that scanned the whole sky and
try to spot these things. But again, you can only
notice them, you know, after they happen. We'd love to
(28:08):
study them just before they happen, so we can see
what's causing it, right, because I guess we UM. I mean,
they do surveys of the sky that they're always looking
at stars, but to get enough of information from the
one that blew up is hard because you have to
sort of focus on it. Yeah, and you'd love to
use our most powerful telescopes. And we have sort of
two kinds of telescopes. Ones that are really broad they
(28:30):
can image the whole night sky, but they're not that powerful,
and ones that can look really deeply at one object,
like the hubble, you know, but it can't really scan
the whole night sky because it's it has to point
really carefully at one thing. I see. So even with
the early warning system of the neutrinos, we can't that
won't tell us which star is gonna blow. That's what
(28:51):
we try to do. We try to see the neutrinos
and then like whip stuff around. But you know, neutrinos
are hard to spot because even a gazillion of them
will come through the Earth and not interact. And you know,
new tunion detectors are sometimes busy doing other things, are
not dedicated to supernova's. They try to hook these things up,
and when the neutrinos tell us the superno is coming,
they point in that direction. And so we do our best,
(29:12):
because remember, the supernovas have taught us a lot about
the universe. They're the ones that gave us the clue
that the universe is expanding. All right, So that that's
the first way that a star can goes supernova is
it's happily retired, but then it gets something triggers it,
and it just goes out in a blaze of glory,
runaway blaze of glory. That's right. It was saving up
(29:34):
for one last hurrah. All right, Let's get into the
second way in which supernose can happen, But first let's
take a quick break, al right, Daniel. So the second
(29:54):
way that uh supernova can happen is called core collapse.
And I think this is maybe the one that most
peop we're familiar with. Why why is this one? More?
I guess popular this is the case where gravity wins
in the epics struggle with fusion. I think this one's
maybe more awesome. I mean, I don't mean anything negative
about runaway fusion the size of a star glowing five
(30:15):
billion times brighter than the sun. But this one involves
implosion and explosion, so maybe it's like double awesome. Okay,
so there's some implosion involved in this one, right, I
guess it's in the word core collapse. Yeah. So in
this scenario, again, you start as a really big star.
You've gotta be our big enough star to even consider
going supernova, like a star like our Sun is never
(30:36):
going to go supernova. Hey, that's good to know, and
be what do you mean big? Like, what's the threshold
for supernova? Is it like many times the size of
our sun or a little bit more. It's like five
to eight times in the mass of the Sun is
like the bare minimum you need to have a supernova.
Beyond that, you can't even get an agent to return
your phone. Yeah, you're forever be list which I think
(30:59):
is a good thing. But this sort of core collapse
superno requires a really big star. And we were talking
earlier about what's happening inside the stars. You have this
fusion and you're creating heavier and heavier stuff. Well, in
some stars they are big enough to fuse carbon, and
then they fuse the byproducts of carbon and make heavier stuff,
and the byproduct of that make even heavier stuff. So
(31:20):
it's a bigger factory, and it goes beyond what these
other stars that we talked about can do. They can
actually fuse carbon and and uh and make heavier and
heavier elements. But it's sort of a more controlled process
because it's happening gradually. It's like an equilibrium. Stuff is
slashing back and forth, and the carbon fuses and turns
into the next thing. And these guys confuse all the
(31:41):
way up to iron. Remember that up to iron, when
you have fusion, you release energy. Above iron or nickel
or so when you fuse it absorbs energy and so
it would cool the star down. So like what comes
right before iron. Yes, so iron is number twenty six
and nicholas, and that's about as high as you can go.
I mean below that you have oxygen at eight you
(32:03):
can make you make magnesium a twelve aluminum silicon. Anything
below iron, when you fuse it together, releases energy so
that that sustains the explosion of the star. But you're saying,
after iron, if I want to fuse more things, I
have to sink energy into it. Yeah, and so it
actually sucks energy out of the star. It starts to
(32:25):
cool it. And this is the enemy of the star.
The star remembers trying to well, it doesn't like feel
anything or want anything. But if a star is going
to continue to burn, it needs to exert outward pressure
against gravity. But it's sort of working against itself because
it's making heavier and heavier stuffed. And so you know,
as it's making heavier and heavier stuff, it's making the
(32:46):
gravity stronger and more powerful because it's getting denser at
its core. And so if you're then also cooling down
your own reaction, then you're fighting against yourself. Wow. So
and eventually what happens. It winds like you run out
of things to fuse. Everything's iron, and then gravity wins. Yeah,
eventually gravity wins and it pulls itself together and it
(33:10):
collapses and gravity says, all right, I'm blowing past you.
And there's this point it's called the Chandra Shaker limit.
It's essentially when matter cannot be squeezed anymore. Let's see
when all the electrons are pushed down into their lowest orbitals,
and everything is tucked as close as possible, and that's
what like a white dwarf for a neutron star is
(33:30):
sitting at. But when gravity has enough power to overcome that,
that electron degenerously. When you have too much stuff, then
it collapses and gravity takes over, meaning that um, whatever
is keeping the star kind of fluffy, it's no longer enough.
Burned too much, and now it's it's too heavy. Yeah,
there's not enough outwards pressure and there's growing gravitational pressure inwards,
(33:54):
and so eventually gravity just overwhelms it, and that's when
you get this core collapse. I guess collapse means that
it it's just sort of like folds folds in or
what does that mean? Like all the Adams were happy
sort of bunched together, but now they crunched in together more. Yeah,
and you actually get an inwards going shock wave. And
so people sometimes talk about supernovas as implosions and that's why,
(34:16):
because you get this shock wave of stuff rushing in
towards the center. Wow, because the in the innerts of
the star are I guess collapsing before they were sort
of fluffy from all the energy. But now they're just
they're out of energy, so that everything's just crunching together.
To think about the surface of the star, what's happening
there is it's constantly getting pulled in by all the
(34:38):
heavy stuff inside the star, and it's getting pushed out
by the burning. Eventually, if the burning is not strong enough,
you know, if it passes this limit, then that stuff
gets pulled in and it compresses the next layer, which
compresses the next layer, which compresses the next layer. And
it's a runaway process because the more you compress something,
the higher density it is, the stronger the gravitational force, right,
(35:00):
because as you get closer, the gravity stronger. Yeah, so
the whole thing just it just falls inwards. It falls inwards,
and then what happens depends on how much stuff you
started with. And if you're like super duper big, like
more than forty times the mass of our Sun, then
that's basically it. You just collapse into a black hole
without even making a peep. The star just kind of
(35:22):
bloop turns into a black hole. Yeah, you can just
go and suck itself into a black hole without a supernova,
like you can skip the supernova stuff. If you're big, Okay,
so that's if you're really big. If you're really big,
But if you're not big enough, then the core collapse
sort of goes inwards and then it bounces off the hot,
dense core of the start, like the shock wave comes
(35:43):
in and it reaches a point where the stuff is
so dense that it can reflect that shock wave back out,
and that's when the supernova happens. That's when like stuff
flies out from the star. Oh, it's all this energy
of stuff falling in. It's the balance. That's actually the explode. Yes,
it's the bounce. And if you're too big, you don't
get the bounce, right because it just like turns into
(36:05):
a black hole and then nothing can escape. But if
you're if you're below that, if you're like around thirty
times the mass of the Sun, then you get a
bounce that goes out with a supernova and the core
becomes a black hole. Oh really, only the core that
the other stuff bounces away. Yeah, you get the supernova,
this huge shock you know, expus plasma through the universe
(36:26):
and neutrinos and light and energy, but the core of
it remains and becomes a black hole, and that's different
than the other kind of runaway fusion, which didn't form
a black hole. That's right, Those don't usually form a
black hole. Sometimes those can end with a really dense
neutron star, but a lot of times it's just blowing
out most of the mass of the star in the
runaway fusion. In this case, if you're more than forty
(36:47):
times the mass of the Sun, you go straight to
black hole. If you're more than thirty times the mass
of the Sun, you've got a huge supernova when the
bounce turns around and you get a black hole the core.
If you're a little smaller than that, it's the same story.
Things bounce off the center and then explode down to
a supernova, but instead of a black hole the center,
and you get a neutron star, which is like a
(37:09):
really dense massive material, but not quite dense enough to
form a black hole. I see you just you just
become a like a compact star. Yes, you just become
a really compact blob. And then there's a little window
between like seven and ten times the mass of our
Sun where um when the gravitational collapse happens. Then it
(37:29):
causes runaway fusion and the whole thing just blows um
in a huge explosion. So there's all these like pockets
like if you're this big, then you'll go supernova if
you but if you're a little bit smaller you won't.
But then if you're a little bit smaller still you will.
Like we said, the fate of the star depends almost
entirely on its mass, and so there these little windows
(37:49):
like if you're in this window, this happens. If you're
in this window, that happens. It's like, oh, man, I
shouldn't have eaten that last planet now, now now I'm
gonna explode. Literally. Wow, that's interesting. But again, sort of
the common thing about all of these scenarios is that
it's the it's a collapsing star that becomes a supernova, right,
(38:09):
And sometimes it's at the bound. Sometimes it's just it
creates a runaway explosion. Yea. For all these core collapse
they start with really big stars have been big enough
to burn a lot of heavy stuff to go past
the carbon limit and uh, and then to pass this
gender's say, card limit and collapse gravitationally, right, and then
a couple of different things might happen after that. To
(38:32):
be a supernova or not. Yeah, you could be black hole.
You can be black hole plus supernova. You can be
just supernova. You could have as a neutron star. There's
lots of different options there, all right, So I guess
the next question is should we worry about supernova? Is Daniel,
is this something that might happen like with three minute warning,
we'll find out that the star next to us is
going supernova and then and then goodbye Planet Earth? Or
(38:55):
is it unlikely to happen around us? Well, we sort
of trying to calculate two different things. One is how
close would a supernova have to be to be dangerous?
And they figured that if ones within like twenty five
light years or so, it would basically destroy half of
the Earth's ozone layer, because the half that's facing that
star would be fried. And that would be bad because
we'd be suddenly like totally exposed to space. An amount
(39:17):
of X rays deposited on the planet would like sterilize
half the population and or give them cancer instant, Oh
my god, within minutes or within days or very quickly. Yeah,
I mean, does it really matter if it takes days
or minutes to get cancer? You've got cancer. Well, but
everything else would stay the same, like a solar system
would still be here and we'd be going around the
same orbit. Yeah, and you know, that's an interesting question.
(39:38):
People wonder if there are gravitational waves from supernova, but
we've never seen one before. But it wouldn't affect like
the gravity of the Earth. We'd still be orbiting the
Sun the same way. Would just be like you know,
mostly toast. But fortunately, we've looked around and we haven't
spotted anything that we think is going to go supernova,
anything anywhere within the nearest five light years. Now, again,
(39:59):
we don't have a great understanding of when a stargo supernova,
but we think we have a sense for the which
kind of star can go supernova, and we don't see
any of those nearby. And you know, supernovas are not
just bad news, right, supernova is they're sort of part
of the life cycle of the galaxy. You know how
we learned that forest fires aren't all bad because they
helped like clean out dead wood and provide space for
(40:22):
new animals. You know, well, they're good as long as
you don't live in your house is not next to you. Yeah,
exactly that way. It's a sign of a healthy forest
to have occasional small fires. In the same way it's
a sign of a healthy galaxy to occasionally, know, clear
out some of the clutter in the dust and blow
up the old stuff and make room for something new.
Because that is kind of how um heavier materials like
(40:44):
we wouldn't be you and I wouldn't be here if
if it's not for a supernova, and it's not just
the supernova throw that stuff out into the universe. That
is true. But also we wonder about like what makes
a star begin, Like give a big cloud of gas
and dust. Is gravity just like very gradually pulling it
together over billions of years. Some people think that it's
(41:05):
the shock wave from a nearby supernova that sort of
triggers that gravitational collapse of that cloud into a star.
So it might be that the death of a star
the supernova is what you need to form new stars.
Stars begetting stars. It's all cycle, man, it's the circle
of life. Somebody que Elton John, But who who made
(41:26):
the first star? Then, Daniel, what came for as the
star or the supernova? The eternal question? I believe that
one for the philosopher's all right, well, I feel like
I learned a lot about supernovas today. You know, I
thought that they only did the supernova through core collapse.
They didn't know that there were all these other ways
that they can happen. Yeah, supernovura fascinating and we're constantly
(41:46):
studying them because they are dramatic and they're awesome to
learn about, and because we'd like to know, you know,
what happens at the end of life of a star.
It's it's fascinating, it's dramatic, but it's also still mysterious. Yeah,
and it's a big part of how the universe works, right,
like how you make metals and everything all around this,
everything around us is was basically made in a supernova.
(42:08):
Would you say that, like all the metal and components
in your phone, in your car, that all came from
a supernova. All that stuff was fused inside a hot
star billions of years ago. Yes. All right, Well, we
hope you enjoyed that. And the next time you look
up at the night sky and see something getting brighter,
duck or at least close your eyes. At least close
(42:29):
your eyes and look it up online later. All right,
thanks for joining us, See you next time. Before you
still have a question after listening to all these explanations,
please drop us a line. We'd love to hear from you.
You can find us on Facebook, Twitter, and Instagram at
(42:52):
Daniel and Jorge That's one Word, or email us at
Feedback at Daniel and Jorge dot com. Thanks for listening,
and remember that Daniel and Jorge Explain the Universe is
a production of I Heart Radio. For more podcast from
my heart Radio, visit the I heart Radio Apple Podcasts,
or wherever you listen to your favorite shows. Yeah,
Hosts And Creators
Daniel Whiteson
Kelly Weinersmith
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