Speaker 1: Welcome to Bedtime Astronomy. Explore the wonders of the cosmos
Speaker 1: with our soothing Bedtime Astronomie podcast. Each episode offers a
Speaker 1: gentle journey through the stars, planets, and beyond, perfect for
Speaker 1: unwinding after a long day. Let's travel through the mysteries
Speaker 1: of the universe as you drift off into a peaceful
Speaker 1: slumber under the night sky.
Speaker 2: Okay, let's unpack this.
Speaker 3: Let's do it.
Speaker 2: When you and I are really anyone pictures a star dying,
Speaker 2: you know, in a supernova, we're usually imagining just the
Speaker 2: most extreme catastrophic event.
Speaker 3: Possible, ultimate cosmic destruction.
Speaker 2: Yeah, right, a massive, completely chaotic mess. It's this expanding
Speaker 2: cloud of superheated debris. And I love the term astrophysicists use.
Speaker 2: They say it has a texture like a giant turbulent cauliflower.
Speaker 3: It's a great visual and it's accurate. That's the standard
Speaker 3: picture of stellar violence we expect to see.
Speaker 2: But the sources you've shared with us today, they focus
Speaker 2: on this one astronomical object that just it throws that
Speaker 2: entire visual model right out the window completely.
Speaker 3: Yeah.
Speaker 2: It's called pop thirty. And this thing, this remnant, is
Speaker 2: the perfect visual opposite of chaos. It looks like, yeah,
Speaker 2: like an explosion that was frozen right in the middle
Speaker 2: of the burst.
Speaker 3: That's a perfect description.
Speaker 2: It's not defined by swirling clouds at all, but by
Speaker 2: these incredibly long, straight, almost almost geometrically precise filaments, all
Speaker 2: radiating outward from one single point.
Speaker 3: And this exploration it's really a perfect example of connecting
Speaker 3: centuries old observations from the sky with the most cutting
Speaker 3: edge computational physics we.
Speaker 2: Have today, a real bridge between the old and new.
Speaker 3: Absolutely, our whole mission here is to figure out this paradox.
Speaker 3: How can a stellar explosion, one of the most energetic
Speaker 3: events in the entire universe, end up creating something with
Speaker 3: such incredible structural order, right, So we need to figure
Speaker 3: out not just what happened to the star that created,
Speaker 3: which was a white dwarf, but why the debris cloud
Speaker 3: it left behind looks so radically different from pretty much
Speaker 3: every other remnant we study.
Speaker 2: So this is a deep dive into stellar failure.
Speaker 3: It is, and how that failure, weirdly enough became the
Speaker 3: necessary first step for creating this spectacular geometry.
Speaker 2: And this is where it gets for me, just genuinely fascinating.
Speaker 2: We're talking about physics on this immense cosmic scale, with
Speaker 2: material moving faster than any rocket ship we've ever dreamed of.
Speaker 3: Building on believable speeds.
Speaker 2: But the key mechanism, the thing that explains Path thirty's
Speaker 2: unique precise shape, is the exact same principle of fluid
Speaker 2: dynamics that creates the classic iconic shape of a mushroom
Speaker 2: cloud right here on Earth.
Speaker 3: It's the same physics, just on a scale that's hard
Speaker 3: to even comprehend.
Speaker 2: So let's get into it. Let's explore the really complex
Speaker 2: astrophysics that turned what should have been this violent explosion
Speaker 2: into a geometrically structured whimper, a very beautiful whimper. We
Speaker 2: really have to start with that visual contra because it
Speaker 2: is so so striking. It puzzled astronomers for decades, for
Speaker 2: a long long time. If you pull up images of
Speaker 2: remnants from what we call typical type ees supernovae, that's
Speaker 2: the kind of where the star is completely obliterated, you
Speaker 2: see exactly what we're talking about.
Speaker 3: The cauliflower.
Speaker 2: The cauliflower, Yeah, thick, churning, chaotic clouds of ejecta. It's
Speaker 2: the perfect image of massive cosmic turbulence and mixing gas.
Speaker 2: This is what's supposed to happen when a star completely
Speaker 2: and violently tears itself apart.
Speaker 3: And you have to appreciate the energy involved there. A
Speaker 3: standard type E S supernova, I mean, it releases an
Speaker 3: amount of energy and milliseconds that's equivalent to what our
Speaker 3: Sun will put out over its entire multi billion year lifetime.
Speaker 2: It's just an insane amount of power.
Speaker 3: It's incredible. And that sheer instantaneous energy churns up all
Speaker 3: the ejected material so intensely that any little bit of
Speaker 3: structure it might have had at the beginning is just
Speaker 3: it's ripped apart. It's thoroughly mixed, and that's what leads
Speaker 3: to that characteristic chaotic mess.
Speaker 2: And these are the explosions we rely on right as
Speaker 2: cosmic yardsticks we do.
Speaker 3: We call them standard candles because their brightness is so predictable,
Speaker 3: which lets us measure distances across the universe. But the
Speaker 3: debris fields they leave behind are anything but standard in
Speaker 3: their structure. They are, you know, textbook models of total
Speaker 3: cosmic chaos with Then you turn.
Speaker 2: Your telescope to path thirty and it is just so
Speaker 2: distinctively lacking any of those chaotic signatures. It's not a
Speaker 2: cauliflower at all, not even close. Instead, you get these
Speaker 2: incredibly long, sustained straight filaments. They just they radiate outward
Speaker 2: from a central point. The researchers described it perfectly. I
Speaker 2: think they said, it's like the trails from a sparkler
Speaker 2: that have been frozen midburst.
Speaker 3: And that appearance right away it signals a huge anomaly.
Speaker 3: For years, astronomers really struggle to explain the structure precisely
Speaker 3: because it defied all the standard high energy supernova models.
Speaker 2: The question must have been, why is there any structure at.
Speaker 3: All, exactly and how did it stay so straight, so
Speaker 3: linear across these vast distances and over so much time.
Speaker 3: What's so fascinating here is that we can trace PAW
Speaker 3: thirty's timeline way back in history. We now know that
Speaker 3: the event itself corresponds to something that Chinese and Japanese
Speaker 3: astronomers observed way back in the year eleven eighty one.
Speaker 3: They called it a guest star.
Speaker 2: So we're talking about almost nine hundred and fifty years
Speaker 2: of observation here, starting with ancient records and leading all
Speaker 2: the way up to the Hi Ris images. We have today.
Speaker 2: That's right, okay, So if the event was observed back then,
Speaker 2: do those historical records tell us anything about what kind
Speaker 2: of explosion it was. Did it look like a normal
Speaker 2: supernova to them?
Speaker 3: And that is a crucial piece of the puzzle. The
Speaker 3: historical records actually support the idea that this was an
Speaker 3: unusual event even back then. The brightness records from eleven
Speaker 3: eighty one. They indicate that this guest star, which we
Speaker 3: now link to PAW thirty with very high confidence, it
Speaker 3: was visible for many months. But this is the critical part.
Speaker 3: It never got as bright as a standard fully detonating
Speaker 3: type iis.
Speaker 2: Supernova ah so is dimmer.
Speaker 3: It was notably dimmer. This suggests it had a lower
Speaker 3: total energy release, or what we'd call a lower peak luminosity.
Speaker 3: This observational fact is one of the key clues. The
Speaker 3: explosion was powerful enough to be seen from Earth, but
Speaker 3: it was not powerful enough to be one of these
Speaker 3: full scale star obliterating events.
Speaker 2: So the ancient astronomers gave us our first clue, a dimmer,
Speaker 2: longer lasting blast, and modern astronomersy the aftermath a strangely
Speaker 2: geometric remnant.
Speaker 3: Exactly that ninth century gap between the observation and the
Speaker 3: final explanation really highlights how complex this problem was.
Speaker 2: But the recent research, the work spearheaded by Eric Coughlin
Speaker 2: and his team at Syracuse University, that's what finally provides
Speaker 2: the unifying concept. It does, and the core finding is
Speaker 2: just it's so simple and profound. The star tried to explode,
Speaker 2: but it didn't fully succeed.
Speaker 3: That that is the critical transformative insight. The star did
Speaker 3: not follow the textbook. It was an incomplete blast. This
Speaker 3: wasn't just a misfire. It's a specific, recognized class of
Speaker 3: stellar death that creates the perfect conditions for this very unique,
Speaker 3: very precise geometry.
Speaker 2: So the fact that the explosion was a partial event,
Speaker 2: a failure if you want to call it that.
Speaker 3: A failure is a good word for it.
Speaker 2: That's what ultimately dictated the fluid physics of the remnant
Speaker 2: we see today. If it had been a full scale
Speaker 2: Type IAD detonation, there would be no Poth thirty, there would.
Speaker 3: Just be another chaotic cauliflower cloud and the star itself
Speaker 3: would be gone forever.
Speaker 2: So the visual signature, this beautiful geometric order, is a
Speaker 2: direct consequence of a failure in nuclear physics. That's the
Speaker 2: foundation that explains this whole nine hundred year old mystery.
Speaker 3: It is, and to really appreciate the details of that failure,
Speaker 3: we should probably quickly walk through the standard type IA
Speaker 3: process first, and then we can see exactly where POTH
Speaker 3: thirty went off the rails.
Speaker 2: Good idea. So where does this start?
Speaker 3: It starts with a white dwarf. Pal thirty came from
Speaker 3: a white dwarf, which is the super dense, extremely compact
Speaker 3: core leftover after a star like our sun, runs out
Speaker 3: of its nuclear fuel.
Speaker 2: And the classic story of white dwarf is that it's
Speaker 2: supposed to be retired, right It just sits there quietly,
Speaker 2: supported by something called electron degeneracy pressure.
Speaker 3: Unless unless it has a friend, a companion star. If
Speaker 3: it's in a binary system, it can start pulling material
Speaker 3: like hydrogen and helium from that companion.
Speaker 2: It starts a creating mass exactly.
Speaker 3: And when it gathers enough mass, it creeps closer and
Speaker 3: closer to this critical threshold called the chondraceccar limit that's
Speaker 3: about one point four times the mass of our side.
Speaker 2: And once it hits that limit, the.
Speaker 3: Core can't resist gravity anymore. The pressure in the heat
Speaker 3: becomes so immense that it triggers runaway carbon fusion deep
Speaker 3: inside the star, and in.
Speaker 2: A normal type event, that first little spark of ignition
Speaker 2: very quickly turns into what's called a supersonic detonation wave.
Speaker 3: Supersonic is the keyword there. It's a wave traveling faster
Speaker 3: than the speed of sound through the star's material, like
Speaker 3: a shock wave of fire a perfect analogy. That detonation
Speaker 3: wave just sweeps through the entire star in a matter
Speaker 3: of seconds, converting carbon and oxygen into heavier elements, mostly
Speaker 3: nickel fifty six. This process concerns the whole white dwarf,
Speaker 3: completely obliterating it and scattering all that newly forged material
Speaker 3: across space.
Speaker 2: And that's what creates those chaotic debris clouds we talked about.
Speaker 2: The star is just gone bitterly destroyed. But Path thirty
Speaker 2: star took a different path. This is what classifies it
Speaker 2: as the distinct type IAX supernova. So what happened to
Speaker 2: that detonation wave.
Speaker 3: Well, in the case of Path thirty and other Type
Speaker 3: IX events, the initial nuclear burning did begin. It started
Speaker 3: near the star surface in a process we call a deflagration.
Speaker 3: Think of it like a fast moving flame front, not
Speaker 3: a shock wave.
Speaker 2: So it's burning, but it's subsonic, yes, slower than the.
Speaker 3: Speed of sound exactly. And this is the crucial failure point.
Speaker 3: That subsonic burning front, for whatever reason, failed to transition
Speaker 3: into a full supersonic detonation wave that would have propagated
Speaker 3: through the rest of the star.
Speaker 2: It lit the fuse, but the bomb didn't go off properly.
Speaker 3: That's it. The burning front stalled, or maybe it was
Speaker 3: just too slow and inefficient, so instead of a complete
Speaker 3: stellar detonation, you get this partial subsurface explosion. The source
Speaker 3: material calls it a fizzle, which you know, is still
Speaker 3: a tremendously powerful event by our standards, but on a
Speaker 3: cosmic scale, it's a failure.
Speaker 2: And the incredible immediate result of this fizzle is the
Speaker 2: real key to path thirties geometry. The star itself wasn't destroyed.
Speaker 3: That's the most important physical outcome. The star survived a
Speaker 3: hypermassive white dwarf, profoundly shaken, partially burned, certainly changed by
Speaker 3: the energy release, but it survived that initial failed blast
Speaker 3: and it is still sitting there intact at the very
Speaker 3: center of the remnant today. Wow and this phenomenon, the
Speaker 3: lower brightness of the explosion and the survival of the
Speaker 3: stellar core. That is the defining feature of these type
Speaker 3: IX supernovae. They're rare, you know. They only account for
Speaker 3: a small fraction of all the white dwarf explosions we've seen,
Speaker 3: but we're recognizing more of them as we get more
Speaker 3: data on these unusual ways for stars to die.
Speaker 2: It's a spectacular failure and it gives us this incredibly rare,
Speaker 2: detailed data point. But let me challenge the premise a
Speaker 2: little bit. Please, If the explosion failed, if it was
Speaker 2: just a fizzle, where did all the energy come from
Speaker 2: to launch this sustained outflow of material moving at fifteen
Speaker 2: thousand kilometers per second. That speed is just immense This
Speaker 2: vastly faster than the Earth orbits the Sun. A failed
Speaker 2: blast shouldn't be able to generate that kind of power
Speaker 2: over a long time, should it.
Speaker 3: That is a brilliant question, and it gets to the
Speaker 3: really complex transient physics that happened in the moments right
Speaker 3: after the failed blast. The energy source is a combination
Speaker 3: of that initial partial burn and the dynamics of the
Speaker 3: star that's left over. Okay, so when that subsurface nuclear
Speaker 3: burn happened. It created this massive, superheated, dense shell of
Speaker 3: heavy elements, mostly near the stars surface. But because the
Speaker 3: full detonation wave never happened, that heavy shell didn't just
Speaker 3: fly off into space cleanly. Some of it fell back,
Speaker 3: a lot of it expanded violently, and then, yes, a
Speaker 3: significant portion of it began to fall back onto the
Speaker 3: surviving cour due to its immense gravity, so you get
Speaker 3: a rebound effect exactly. The failed blast creates this massive
Speaker 3: pressure wave that travels inward, bounces off the surviving still
Speaker 3: intact core, and then rebounds as a hyper fast, outward
Speaker 3: moving shockwave.
Speaker 2: Like a cosmic pogo stick in a way.
Speaker 3: Yes, this intense shockwave, which is driven by the post
Speaker 3: explosion thermal pressure and these fallback dynamics, it acts like
Speaker 3: a cosmic cannon. It immediately starts launching an extraordinarily fast,
Speaker 3: dense wind of that partially burned material out into space.
Speaker 3: And this sustained stellar wind moving its speeds up to
Speaker 3: fifteen thousand kilometers per second. That is the true engine
Speaker 3: that creates the geometry we see today.
Speaker 2: And we also know the composition, which I think is
Speaker 2: critical for what comes next. This wind wasn't just hydrogen.
Speaker 2: It was enriched with heavy elements.
Speaker 3: Yes, absolutely, the material being launched at these hypervelocities was
Speaker 3: made of the very elements forged during that brief failed
Speaker 3: nuclear burn near the surface, things like iron, silicon, other
Speaker 3: heavy products.
Speaker 2: So you have a tremendously fast, heavy, and crucially a
Speaker 2: dense stream of material being continuously shot outward from the
Speaker 2: star that refused to die.
Speaker 3: That's the perfect combination hypervelocity, high density, and sustained duration.
Speaker 3: That sets the stage perfectly for the unique geometry, which
Speaker 3: is governed by some very basic but very powerful principles
Speaker 3: of fluid dynamics.
Speaker 2: It really transforms the surviving white dwarf. It's not just
Speaker 2: a remnant anymore. It's become a perpetual high speed fluid injector.
Speaker 3: That's exactly what it is.
Speaker 2: So let's make that transition. Then we go from a
Speaker 2: failure in nuclear physics to a success in fluid dynamics.
Speaker 2: We have this surviving white dwarf. It's launching a wind
Speaker 2: at fifteen thousand kilometers per second. It's dense, it's rich
Speaker 2: and heavy elements. When this dense, fast wind slams outward
Speaker 2: into the lighter much much sparser gas that's just sitting
Speaker 2: around in that area the interstellar medium. That surface where
Speaker 2: they meet becomes a physics laboratory.
Speaker 3: It does. That interface is where all the action happens.
Speaker 3: It's where the characteristic Sparkler structure of Paul thirty is born.
Speaker 3: From this point on, fluid dynamics dictates everything about the
Speaker 3: remnant's shape.
Speaker 2: And that meeting point where the dense fast stuff hits
Speaker 2: the sparse slow stuff. It's not stable, is it not
Speaker 2: at all?
Speaker 3: It's highly unstable, and that inherent instability is the absolute
Speaker 3: key to forming those long, straight filaments.
Speaker 2: Okay, let's talk about that first critical instability, the one
Speaker 2: that connects this cosmic event to something we can actually
Speaker 2: visualize here on Earth. The Raleigh Tailor instability or RT.
Speaker 3: The Raley tailor instability is a really fundamental phenomenon in
Speaker 3: fluid dynamics. It describes what happens when you have two
Speaker 3: fluids of different densities and you have an acceleration force
Speaker 3: that's directed from the dense fluid toward the light fluid.
Speaker 2: It sounds technical, but the idea is simple.
Speaker 3: It is, if a dense fluid pushes into a lighter fluid,
Speaker 3: or if you have some acceleration force acting across that boundary,
Speaker 3: the interface between them becomes unstable and the two fluids
Speaker 3: will try to mix in a very particular way.
Speaker 2: And the classic macroscopic example that everyone knows, even they
Speaker 2: don't know the scientific term for it is the shape
Speaker 2: of a mushroom cloud from a nuclear explosion.
Speaker 3: Correct that iconic mushroom shape is driven almost entirely by
Speaker 3: RT instability. The intense heat of the initial blast creates
Speaker 3: this massive bubble of hot, low density gas inside.
Speaker 2: The fireball, and hot air rises.
Speaker 3: Right it rises rapidly through the cooler, much denser surrounding air.
Speaker 3: In that case, gravity provides the acceleration, effectively pulling the
Speaker 3: denser air down and around the lighter rising fluid, and
Speaker 3: that density difference, coupled with the acceleration, causes the boundary
Speaker 3: to become unstable and form those characteristic swirling shapes and
Speaker 3: the big fingers or plumes that make up the mushroom cap.
Speaker 2: Okay, So if P thirty is basically a colossal cosmic
Speaker 2: version of that, we have to address one key difference
Speaker 2: in space. On this scale, gravity is pretty much irrelevant
Speaker 2: compared to the kinetic forces. At play. So what force
Speaker 2: is replacing gravity to define that density interface and drive
Speaker 2: the instability.
Speaker 3: That is the essential insight you need when you apply
Speaker 3: terrestrial fluid physics to astrophysics. In Better thirty, the acceleration
Speaker 3: isn't provided by a universal force like gravity. It's provided
Speaker 3: by the relentless, sustained kinetic pressure of that outgoing stellar wind.
Speaker 2: So the wind itself is the force.
Speaker 3: Yes, the dense high speed wind acts like a piston.
Speaker 3: It's forcefully accelerating the lighter interstellar material out of its way.
Speaker 3: The rapid deceleration of that heavy wind as it smacks
Speaker 3: into the lighter gas that creates the necessary conditions for
Speaker 3: RT instability to kick off. Right at that boundary. The
Speaker 3: inertia of the dense, fast moving wind is so immense
Speaker 3: that it acts as the primary driving force pushing into
Speaker 3: the static light medium.
Speaker 2: So the energy injection itself is the accelerating force. The
Speaker 2: dense heavy wind pushing the light ambient gas forward is
Speaker 2: what causes those initial fingers to sprout.
Speaker 3: Precisely, the conditions at the boundary between the dense fast
Speaker 3: stellar wind and the surrounding interstellar gas were just perfect
Speaker 3: for RT instability. You have a dense, heavier wind pushing
Speaker 3: forward fully and continuously into a lighter surrounding material. This
Speaker 3: interaction causes prumes or fingers to develop at the interface,
Speaker 3: and they stretch out into the material ahead of them.
Speaker 2: And in Paul thirty, those are the plumes that grew
Speaker 2: into the long, straight filaments we see today.
Speaker 3: They are the very same structures.
Speaker 2: Yes, but that immediately brings us right back to the
Speaker 2: central puzzle of Path thirty. If our key instability creates
Speaker 2: these fingers, why are they long, straight and sustained In
Speaker 2: most supernova remnants we look at those RT fingers might
Speaker 2: appear for a split second, but then they're immediately ripped
Speaker 2: apart and mixed into total chaos.
Speaker 3: That's right. They're incredibly transient.
Speaker 2: So if you just look at the physics of a
Speaker 2: normal explosion, all of this beautiful order should just break
Speaker 2: down immediately.
Speaker 3: And that is the fundamental difference that makes path thirty
Speaker 3: so important for us to study. We are witnessing a
Speaker 3: physical condition that is actively suppressing the subsequent processes that
Speaker 3: normally generate chaos. Path thirty stays orderly because something is
Speaker 3: preventing those fingers from being sheared apart.
Speaker 2: It's the difference between a high energy explosion it just
Speaker 2: immediately collapses into this disorganized turbulence and a continuous, sustained
Speaker 2: process that maintains that structure well for nine centuries in counting.
Speaker 3: And this brings us to the key physical insight that
Speaker 3: the computational modeling uncovered. The preservation mechanism is the extreme
Speaker 3: high density contrast between the two materials, and it's the
Speaker 3: effect that has on a second, usually dominant instability.
Speaker 2: Okay, you mentioned a second instability, the one that usually
Speaker 2: causes all the chaos. Let's name it and define what
Speaker 2: it normally does in a typical remnant.
Speaker 3: We have to talk about the Kelvin Helmholtz instability or
Speaker 3: k H. It's another fundamental concept where a Ralegh tailor
Speaker 3: happens when fluids accelerate across a density boundary. Kelvin Helmholtz
Speaker 3: happens when fluids of different speeds move parallel to each
Speaker 3: other along a boundary. This creates intense shearing and mixing.
Speaker 2: The classic example is wind blowing across the surface of water. Right,
Speaker 2: it creates waves.
Speaker 3: Perfect example that share between the fast moving air and
Speaker 3: slower moving water creates waves which eventually break and mix
Speaker 3: the air and water together. It's a mixing instability.
Speaker 2: So in a typical full blown supernova, you get the
Speaker 2: initial RT fingers forming, but the extremely high velocities and
Speaker 2: the turbulent motions at the interface immediately cause cage instability
Speaker 2: to kick.
Speaker 3: In precisely, and cage instability just tears those RT fingers
Speaker 3: to shreds almost instantly. The material flows are so turbulent
Speaker 3: and they shear against each other with such violence that
Speaker 3: any structure is destroyed. That chaotic turbulent mixing is what
Speaker 3: makes standard supernova remnants look messy. That cauliflower shape is
Speaker 3: often a direct result of KH instability tearing up the
Speaker 3: initial RT structures.
Speaker 2: So chaos is the default state for a cosmic explosion.
Speaker 3: It is, which.
Speaker 2: Means that for Paianati to have this geometry, the cage
Speaker 2: instability must have been somehow suppressed or damped down. So
Speaker 2: how does a high density contrast do that.
Speaker 3: It's all about inertia. The wind that was launched by
Speaker 3: that surviving white dwarf was so much much heavier, so
Speaker 3: much denser than the surrounding interstellar gas that the mixing instability,
Speaker 3: the KH instability, just never got a chance to dominate, so.
Speaker 2: It couldn't get a grip. Basically, it couldn't.
Speaker 3: The source material notes that the density ratio between the
Speaker 3: ejecta from the star and the ambient medium around it
Speaker 3: was extraordinarily large.
Speaker 2: So it's like trying to shear a very dense, thick
Speaker 2: cold syrup that's being pushed forward with tremendous force against
Speaker 2: extremely light still air. The sheer difference in mass and
Speaker 2: inertia prevents that lighter medium from being able to quickly
Speaker 2: rip apart the heavier one.
Speaker 3: That is an excellent analogy. The dense fluid has far,
Speaker 3: far greater inertia, and that effectively damps down the sheer
Speaker 3: forces that would normally lead to that rapid Kelvin Helmholtz mixing.
Speaker 3: The dense material just keeps plowing forward in a linear.
Speaker 2: Path, and it wasn't a one time push.
Speaker 3: That's the other critical piece. The filaments were being continuously
Speaker 3: fed by that ongoing dense wind being launched from the
Speaker 3: surviving white wharf. This continuous high density injection was the
Speaker 3: preservation mechanism. It kept the fingers stretching outward and actively
Speaker 3: resisted the forces that would normally cause them to shred
Speaker 3: into chaos.
Speaker 2: So the high density contrast means the order persists, the
Speaker 2: ongoing injection of material means the structure sustained over time,
Speaker 2: and that combination gives us PAN thirty's visually stunning distinctive
Speaker 2: firework appearance that can last for centuries.
Speaker 3: And the computational work, the work done by Kaughlin's team
Speaker 3: it confirmed this beautifully. They used these very high resolution
Speaker 3: three D hydrodynamical simulations which let them isolate the effect
Speaker 3: of the density ratio on how these instabilities developed.
Speaker 2: So they could turn the knobs. Basically, they could turn.
Speaker 3: The knobs, and their models demonstrated that when you input
Speaker 3: conditions involving extremely high density contrasts where the injected fluid
Speaker 3: is hundreds or even thousands of times denser than the
Speaker 3: ambient medium, you produce exactly these types of long, straight,
Speaker 3: sustained filamentary structures.
Speaker 2: So the geometry isn't just some leftover.
Speaker 3: Axis, not at all. It's an active, continue muously fed
Speaker 3: structure that's governed by very very specific conditions in fluid physics.
Speaker 2: What I find utterly fascinating is that the research drew
Speaker 2: this unexpected parallel to real world, highly constrained experiments that
Speaker 2: were conducted right here on Earth, you know, a long
Speaker 2: way from the core of a star.
Speaker 3: Yes, the connection to declassified data from atmospheric nuclear tests
Speaker 3: is probably one of the most compelling plulks of this
Speaker 3: entire study. It links fluid dynamics across these radically different scales,
Speaker 3: from the surface of a star to a test site
Speaker 3: in the Pacific Ocean.
Speaker 2: And they look specifically at photographs from the nineteen fifty
Speaker 2: two Kingfish nuclear test. That was an event studied specifically
Speaker 2: for its atmospheric effects, right.
Speaker 3: That's right, for fallout dispersion and things like that.
Speaker 2: So what did those Kingfish photos show that was so
Speaker 2: relevant to a star that exploded centuries ago.
Speaker 3: They showed that immediately after the detonation began, these striking
Speaker 3: filamentary patterns formed within the rising fireball. It was clear
Speaker 3: visual proof.
Speaker 2: So it proved unequivocally that RT instability works the same
Speaker 2: way whether your energy source is a stellar core or
Speaker 2: a nuclear war hit.
Speaker 3: Exactly. The initial physics of density instability is universal. It
Speaker 3: doesn't care about the scale.
Speaker 2: But the source material highlights the really crucial difference in
Speaker 2: how the two events evolved over time. The Kingfish test
Speaker 2: ended up as a mushroom cloud, while Paw thirty ended
Speaker 2: up as a sparkler. Why did they diverge.
Speaker 3: The difference is timing, duration, and the nature of the
Speaker 3: energy source. The nuclear test is what we call an
Speaker 3: impulsive energy.
Speaker 2: Release, a single instantaneous.
Speaker 3: Burst right, a massive amount of energy in a fraction
Speaker 3: of a second, and then a very rapid drop off
Speaker 3: in the driving pressure. So in the Kingfish test, while
Speaker 3: you saw those initial rt fingers form, the driving force
Speaker 3: quickly vanished and the atmosphere's own turbulence, driven by those
Speaker 3: intense sheer forces, rapidly took over.
Speaker 2: So the kh instability won out.
Speaker 3: In the end, it did. Those initial filamentary patterns quickly
Speaker 3: evolved into the chaotic expected classic qualiflyer shape because the turbulence,
Speaker 3: the cage and stability rapidly dominated the structure once the
Speaker 3: initial push was gone.
Speaker 2: But Impal thirty, the star survived exactly.
Speaker 3: And that is everything. The continuous feeding of that dense
Speaker 3: stellar wind from the surviving white dwarf was the preservation mechanism.
Speaker 3: It wasn't an impulsive event. It was a sustained energy
Speaker 3: and mass injection that has been going on for centuries.
Speaker 2: And that sustained pressure.
Speaker 3: That continuous pressure maintained the high density contrast, which allowed
Speaker 3: the RT fingers to just keep growing, keeps stretching linearly,
Speaker 3: and resist the kh driven turbulence that would normally morph
Speaker 3: them into chaos. It's the duration and the density of
Speaker 3: the driving force that allows this beautiful order to persist
Speaker 3: over centuries.
Speaker 2: It is just a staggering realization. The entire reason potharity
Speaker 2: looks the way it does is because the explosion failed
Speaker 2: in this very specific way, which resulted in a sustained
Speaker 2: dense engine, the surviving star that just keeps feeding highly
Speaker 2: structured fluid outward for almost a thousand years.
Speaker 3: In this knowledge, it has implications that go far beyond
Speaker 3: just this one remnant this mechanism where an extremely high
Speaker 3: density contrast preserves RT driven structure by suppressing kge mixing,
Speaker 3: it suggests that we might see similar filamentary structures, either
Speaker 3: transiently or perpetually in other astrophysical phenomena.
Speaker 2: Anytime you have very dense materials slamming into a lighter.
Speaker 3: Medium, that's the condition to look for.
Speaker 2: So we're talking about potentially identifying whole new visual signatures
Speaker 2: for other kinds of cosmic violence? Where else might this
Speaker 2: be happening?
Speaker 3: While the researchers point toward events like tidal disruption events
Speaker 3: or TDEs, that's.
Speaker 2: Going a black hole tears a star apart.
Speaker 3: Exactly when a star gets too close to a supermassive
Speaker 3: black hole, the tidal forces shred it. Some of that
Speaker 3: stellar material gets swallowed, but a lot of it is
Speaker 3: ejected outward at enormous.
Speaker 2: Speeds, and that debris would be extremely.
Speaker 3: Dense, extremely dense, and it's slamming into the much lighter
Speaker 3: gas that typically surrounds a black hole. So if the
Speaker 3: physics holds true, we might expect to see transient straight
Speaker 3: pan thirty like filaments being formed during TDEs, and that
Speaker 3: could give us brand new observational tools to understand the
Speaker 3: outflow dynamics from black holes.
Speaker 2: So studying this one rare failed stellar death helps us
Speaker 2: map out the entire family of violent cosmic events. It
Speaker 2: transforms the eleven eighty one guest star from a historical
Speaker 2: footnote into a working laboratory for stellar evolution and fundamental
Speaker 2: fluid physics.
Speaker 3: It absolutely does. It forces us to reconsider what chaos
Speaker 3: in space really means. It shows us that sometimes under
Speaker 3: very specific conditions. You can impose this incredible geometric order
Speaker 3: on events that should, by all rights be utterly turbulent.
Speaker 2: This has been an incredibly deep and satisfying dive. We've
Speaker 2: really journeyed from a celestial anomaly, this guest star, documented
Speaker 2: almost nine hundred and fifty years ago by Chinese and
Speaker 2: Japanese astronomers, all the way to the complex world of
Speaker 2: computational fluid dynamics.
Speaker 3: That's huge leap.
Speaker 2: We've established that the bizarre geometry of Path thirty, this
Speaker 2: stellar sparkler, isn't an accident, a direct result of a
Speaker 2: very specific kind of stellar failure, a type I AX supernova.
Speaker 3: And the synthesis is just so powerful when you lay
Speaker 3: it all out. The star failed to achieve a full
Speaker 3: detonation right that left behind a surviving dense core that
Speaker 3: acts as a continuous injector.
Speaker 2: The little engine, the cud it really is.
Speaker 3: This dense hyperfast wind slams into the lighter interstellar medium,
Speaker 3: creating fingers through the Raley Taylor instability, and crucially, that
Speaker 3: extreme density contrast between the dense ejecta and the light
Speaker 3: ambient gas. It suppresses the usual shredding mechanism. The Kelvin
Speaker 3: Helmholtz instability.
Speaker 2: Which allows those fingers to persist straight and orderly for centuries.
Speaker 3: Right, And this gives us a crucial detailed data point
Speaker 3: about the universe's complex physics that a typical full chaotic
Speaker 3: explosion would have simply annihilated, wiped clean.
Speaker 2: So what does this all mean for you, our listener
Speaker 2: taking this new knowledge forward?
Speaker 3: I think it means that our understanding of cosmic phenomena
Speaker 3: is always always improving, even for events that happened centuries ago.
Speaker 3: But maybe more profoundly, it means we have to always
Speaker 3: be prepared to look beyond the expected chaos. We just
Speaker 3: assumed that high velocity collisions in space must always result
Speaker 3: in uniform, messy turbulence.
Speaker 2: It was the default assumption, it was.
Speaker 3: But if high density contrast is the key to preserving
Speaker 3: these long, straight geometric structures, what other seemingly chaotic cosmic
Speaker 3: events might be hiding underline perfectly straight geometric patterns that
Speaker 3: we just haven't focused on yet.
Speaker 2: You mean you might not have been looking for.
Speaker 3: Them exactly, whether we're observing distant nebulae or the material
Speaker 3: flowing between binary stars, or the outflows from massive black holes.
Speaker 3: Maybe that patterns there that we just haven't focused our
Speaker 3: computational models or our high resolution telescopes on yet because
Speaker 3: we assume they couldn't exist.
Speaker 2: That is a truly provocative thought. It suggests that in
Speaker 2: the cosmos, sometimes the whimper of a partial stellar death
Speaker 2: leaves a far clearer, more precise signature than the ultimate
Speaker 2: bang of a full obliteration.
Speaker 3: The physics of failure gives us the clear geometry of success.
Speaker 2: It does. It really suggests we should always look very
Speaker 2: closely at the anomalies.
Speaker 3: They often hold the clearest physical explanations.
Speaker 2: Well, thank you for joining us for this deep dive
Speaker 2: into the structured chaos of a failed star. We look
Speaker 2: forward to exploring whatever other mysteries you bring us next time.
Speaker 2: The gas
Speaker 3: La