Speaker 1: Welcome to Bedtime Astronomy. Explore the wonders of the cosmos
Speaker 1: with our soothing Bedtime Astronomy 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: Imagine looking up at the night sky and seeing a
Speaker 2: star just erupt right. For centuries, that's what astronomers saw.
Speaker 2: A nova would flare up, and we'd log it as
Speaker 2: this sudden, intense flash of light would get incredibly bright
Speaker 2: and then, you know, slowly and predictably fade away.
Speaker 3: That was the entire story. A simple impulsive explosion. That
Speaker 3: was the model.
Speaker 2: But the actual moment, the blast itself, the shape of
Speaker 2: it unfolding in real time, that was always hitting from us.
Speaker 2: It was just a frustratingly blurry point of light.
Speaker 3: It was a fundamental imitation. I mean, we could measure
Speaker 3: the total light output perfectly, we could analyze the energy,
Speaker 3: we could clock the timing down to the second, all
Speaker 3: the numbers, all the numbers, but the actual physical movement
Speaker 3: of the material, the way it was flowing, whether there
Speaker 3: were lumps, how things were interacting. That was all just
Speaker 3: an inference. It was a guess based on computer models.
Speaker 2: We just didn't have a telescope big enough to see
Speaker 2: the details exactly.
Speaker 3: We lack the resolving power to confirm the mechanics of
Speaker 3: the detonation itself.
Speaker 2: Well, that era of inference is officially over, and for you,
Speaker 2: the curious learner, our mission today is to get right
Speaker 2: into this extraordinary scientific breakthrough, the first high definition images
Speaker 2: of stellar explosion.
Speaker 3: Yeah, this is huge.
Speaker 2: We're going to break down the recent findings from a
Speaker 2: major study in Nature Astronomy and look at exactly how
Speaker 2: scientists managed to capture these stellar eruptions, these novy in
Speaker 2: really unprecedented details.
Speaker 3: And these images they don't just tweak the old models,
Speaker 3: they completely overturned in the decades old assumption that a
Speaker 3: nova is this single symmetrical puff of material.
Speaker 2: It's not a simple balloon inflating.
Speaker 3: Not at all. We now have visual proof of these
Speaker 3: incredibly complex, non uniform shakes. We're talking multidirectional jets, we're
Speaker 3: talking about dramatically delayed injections. It's a whole new ballgame.
Speaker 2: Okay, let's really unpack this because to appreciate just how
Speaker 2: big of a loop this is, we need to understand
Speaker 2: the baseline. We need to get into the physics of
Speaker 2: what's actually exploding here.
Speaker 3: All right, So we are focusing on nova, and it's
Speaker 3: so important to distinguish a nova from his more famous cousin, the.
Speaker 2: Supernova, right, not the same thing at all, not even close.
Speaker 3: A supernova is the final catastrophic death of a massive star.
Speaker 3: It's a one time event that completely destroys the star.
Speaker 2: The nova, on the other hand, is a cyclical thing.
Speaker 2: It happens on a star that's well, technically it's already dead, right,
Speaker 2: that's the key.
Speaker 3: It's a surface level explosion on a dead star that's
Speaker 3: locked into this fatal cosmic dance with the companion.
Speaker 2: So if the star is already dead, what does that
Speaker 2: actually mean and what kind of dead star are we
Speaker 2: talking about here?
Speaker 3: We're talking about a white dwarf. This is the remnant
Speaker 3: of a star like our own Sun. After it exhausts
Speaker 3: its main nuclear fuel, it sheds its outer layers and
Speaker 3: the core collapses down into this incredibly dense, super hot object.
Speaker 2: So you've got something with the mass of the Sun
Speaker 2: squeeze into the size of what the Earth.
Speaker 3: About the size of the Earth. Yeah, it can have
Speaker 3: up to one point four times the mass of the
Speaker 3: Sun crammed into that tiny volume, and that density, that
Speaker 3: concentration of mass is what gives it this immense gravitational pull.
Speaker 2: And it's not held up by normal pressure like a
Speaker 2: regular star. It's something else, something exotics precisely.
Speaker 3: Its structure is maintained by something called electron degeneracy pressure.
Speaker 3: It's a quantum mechanical effect. The electrons are packed in
Speaker 3: so tightly that they physically resist being compressed any further.
Speaker 2: So it's stable. It's basically an inert stellar core just
Speaker 2: sitting there.
Speaker 3: It is. It's stable and inert, but its immense gravity
Speaker 3: is still very very active, and that's what sets the
Speaker 3: stage to the explosion.
Speaker 2: It needs trigger, and that trigger comes from its let's say,
Speaker 2: unfortunate companion star.
Speaker 3: Exactly. This white dwarf is almost always part of a
Speaker 3: close binary system, and it acts like a cosmic thief,
Speaker 3: just pulling material, mostly hydrogen and helium, off its companion.
Speaker 2: It's literally stealing fuel it is.
Speaker 3: This stolen material forms a turbulent, swirling cloud around the
Speaker 3: white dwarf called an accretion disc, and from there it
Speaker 3: spirals down and piles up, forming this shallow, super dense
Speaker 3: layer on the white dwarf's surface.
Speaker 2: Okay, so you have this dead quantum supported core and
Speaker 2: it's now covered in a fresh layer of highly compressed hydrogen.
Speaker 2: What flips the switch? What turns that into a city
Speaker 2: sized hydrogen bomb.
Speaker 3: Well, this is where the specific physics gets really interesting.
Speaker 3: As that hydrogen layer piles up, the immense gravity from
Speaker 3: the white dwarf creates incredible pressure and heat at the
Speaker 3: bottom of that layer. It's being crushed, crushed, and cooked.
Speaker 3: The white dwarf itself is extremely hot, maybe one hundred
Speaker 3: million kelvin, So the base of this new hydrogen envelope
Speaker 3: heats up very quickly.
Speaker 2: But the core itself isn't doing any hugion anymore. It's
Speaker 2: just a hot rock essentially.
Speaker 3: That's right, The core is inert. But here's the key
Speaker 3: to the explosion. That hydrogen layer is supported by the
Speaker 3: same degeneracy pressure as the core, and degenerate matter has
Speaker 3: this weird property where its temperature can skyrocket without its
Speaker 3: pressure immediately increasing to match.
Speaker 2: So in a normal gas, if you heat it up
Speaker 2: it expands and cools.
Speaker 3: Right, it's a natural thermostet.
Speaker 2: But that doesn't happen here.
Speaker 3: It doesn't happen here. The temperature just keeps climbing and climbing.
Speaker 3: It's a runaway heating process. And when it hits the
Speaker 3: critical threshold some are around ten to twenty million kelvin,
Speaker 3: that hydrogen suddenly ignites.
Speaker 2: And we're not talking about a slow burn.
Speaker 3: Oh no, it's a catastrophic, runaway thermonuclear reaction. The CNO
Speaker 3: cycle carbon nitrogen oxygen fusion kicks in, violently, releasing a
Speaker 3: massive amount of energy that finally overcomes the star's gravity.
Speaker 3: It blasts that entire accumulated layer into space at thousands
Speaker 3: of kilometers per second.
Speaker 2: And that's the flash. That's the nova we see, that's
Speaker 2: the nova.
Speaker 3: The star temporarily brightens by many, many orders of magnitude.
Speaker 2: An incredible blast, and yet for all of history we
Speaker 2: could only interpret it. The material expands so fast that
Speaker 2: even our best single telescopes just saw it as that single, smooth,
Speaker 2: unresolved point of light.
Speaker 3: That was the historical observation challenge. Yeah, because they're so
Speaker 3: far away, even something expanding in say five thousand kilometers
Speaker 3: per second still looks like a tiny, slowly growing blob.
Speaker 3: We knew mass was being ejected, but we couldn't resolve
Speaker 3: the geometry.
Speaker 2: The shape, the direction, whether there were jets or clumps.
Speaker 3: All that was hidden in those crucial first few hours
Speaker 3: and days.
Speaker 2: So because the geometry was hidden, the physics of the
Speaker 2: explosion was well. It was based on the assumption that
Speaker 2: it was symmetrical, right, like a perfectly inflated balloon.
Speaker 3: Exactly, and that created a huge knowledge gap, I mean understanding.
Speaker 3: The geometry is everything because it dictates how the ejected
Speaker 3: material interacts with itself.
Speaker 2: If it's a smooth sphere, the physics is pretty.
Speaker 3: Straight, relatively simple, yes, But if you have multiple outflows
Speaker 3: or lumpy bits or directed jets, then they're going to crash.
Speaker 2: Into each other and that's where things get interesting.
Speaker 3: That's where you get intense shockwaves, and those shockwaves are
Speaker 3: where the highest energy physics, the particle acceleration, takes place.
Speaker 3: Before this study, the true complexity of those shock powered
Speaker 3: processes was a complete mystery. We were modeling simple physics
Speaker 3: because we couldn't see the complex reality.
Speaker 2: So, given this massive barrier, this fundamental limit of distance
Speaker 2: and resolution, what was the breakthrough? How did we finally
Speaker 2: see the physics as it happened.
Speaker 3: The answer is a really advanced technique called long baseline
Speaker 3: optical inoferometry.
Speaker 2: It sounds incredibly complex, but the basic idea is a
Speaker 2: clever way to shoot the system right, to get around
Speaker 2: the problem of building impossibly large telescopes.
Speaker 3: That's a perfect way to describe it. Look, if you
Speaker 3: want higher resolution, the ability to see finer details, you
Speaker 3: just need a bigger mirror, a bigger aperture.
Speaker 2: Building a single mirror beyond what eight or ten meters
Speaker 2: in diameter is just an immense engineering challenge.
Speaker 3: Immensely complex and incredibly expensive. Yeah. So interferometry solves this
Speaker 3: by combining the light waves from multiple physically separate telescopes.
Speaker 2: So instead of one giant, one hundred meters mirror, you
Speaker 2: can have, say, a handful of smaller mirrors spread out
Speaker 2: over one hundred.
Speaker 3: Meters exactly, and the combined system acts as if it
Speaker 3: were a single giant telescope whose diameter is equal to
Speaker 3: the maximum distance between any two of the smaller ones.
Speaker 2: It creates a synthetic aperture.
Speaker 3: That's the term. The resolution you get is dictated by
Speaker 3: that longest baseline, not the size of the individual mirrors,
Speaker 3: and this lets astronomers achieve resolutions equivalent to a mirror
Speaker 3: hundreds of meters across. It's just phenomenal.
Speaker 2: And we should stress this isn't some brand new, untested idea.
Speaker 2: This is the same powerful technique that was crucial for
Speaker 2: the Event Horizon telescope project, the.
Speaker 3: One that gave is the first ever image of a
Speaker 3: black hole shadow.
Speaker 2: Right, So when we're talking about resolving power, this is
Speaker 2: the absolute cutting edge.
Speaker 3: It really is. And the specific facility that pulled off
Speaker 3: this nova breakthrough is the Center for High Angular Resolution Astronomy.
Speaker 3: The Chair Array app in California.
Speaker 2: Tell us about that setup because it's at a really
Speaker 2: historic site, but the tech itself is I mean, it's
Speaker 2: borderline science fiction.
Speaker 3: It's a wonderful marriage of history in the future. The
Speaker 3: Chair Array is at the Mount Wilson Observatory in the
Speaker 3: San Gabriel Mountains, which is famous for Edwin Hubble's work
Speaker 3: discovering the expansion.
Speaker 2: Of the universe, a legendary place in astronomy.
Speaker 3: Absolutely, and the array itself consists of six one meter telescopes.
Speaker 3: These six telescopes are arranged very precisely along three arms
Speaker 3: in a big y shape. The longest distance between any
Speaker 3: two of them is three hundred and thirty meters, so.
Speaker 2: You're getting the resolving power of a three hundred and
Speaker 2: thirty meter telescope. That's just it's mind boggling. But it
Speaker 2: requires this almost impossible feat of engineering. You have to
Speaker 2: get the light from all six separate telescopes to arrive
Speaker 2: at the central lab at the exact same time.
Speaker 3: Down to fractions of a wavelength light.
Speaker 2: How do you even do that?
Speaker 3: That is the core technical challenge. It's called maintaining coherence.
Speaker 3: Light travels at a finite speed, so you have to
Speaker 3: compensate for the different distances. Chera uses these incredibly precise
Speaker 3: systems of movable mirrors on railway tracks. They're called delay lines.
Speaker 2: And they're all inside sealed vacuum pipes right to keep
Speaker 2: the atmosphere from messing.
Speaker 3: With the light correct The light from eachy telescope is
Speaker 3: beamed into these vacuum pipes, and these delay lines physically
Speaker 3: move back and forth, constantly adjusting the path length of
Speaker 3: the light to make sure all six beams are perfectly
Speaker 3: synchronized when they meet and interfere in the central lab.
Speaker 2: The precision must be on the order of nanometers.
Speaker 3: It is. They have to align the light paths with
Speaker 3: unbelievable accuracy to track the interference pattern the fringes and
Speaker 3: build up a coherent image. And it's all happening in
Speaker 3: real time. Because the Earth is rotating, the object is
Speaker 3: moving across the sky, those pathlengths are constantly changing.
Speaker 2: That level of coordination is already a huge feed. But
Speaker 2: for something like a nova, I mean, you can plan
Speaker 2: for years to image a static target like a black hole.
Speaker 2: A nova just appears.
Speaker 3: And that's what makes this so impressive. It requires immense
Speaker 3: operational flexibility. A nova can brighten dramatically in less than
Speaker 3: a day. The team has to be able to drop everything,
Speaker 3: pivot the entire array, all six telescopes, all the optics,
Speaker 3: all the synchronization, and lock onto this new target immediately.
Speaker 2: It's high stakes, rapid response science.
Speaker 3: It really is. But the visual data from Shira, as
Speaker 3: powerful as it was, was only half the picture. They
Speaker 3: used a really smart, complimentary approach to double.
Speaker 2: Check their work, so they weren't just relying on the
Speaker 2: images alone.
Speaker 3: No, the sharp images from the interferometry told them the
Speaker 3: shape and the structure, but they complimented that data with
Speaker 3: spectra gathered from major observatories like Gemini.
Speaker 2: And the spectra that's like the chemical fingerprint of the
Speaker 2: guests exactly.
Speaker 3: Yeah. It tells you it's velocity, its density, it's temperature,
Speaker 3: it's chemical composition, all the physics.
Speaker 2: So you have the geometry from one instrument and the
Speaker 2: physics from another, and you can marry them up.
Speaker 3: And this is where their confidence just soared. The study
Speaker 3: found what they called a powerful one to one confirmation.
Speaker 3: As soon as a new high velocity feature appeared in the.
Speaker 2: Spectra, meaning a burst of fast moving gas or a
Speaker 2: strong collision.
Speaker 3: That spectroscopic signal lined up perfectly with a new structure,
Speaker 3: a new lump or jet that simultaneously appeared in the
Speaker 3: interferometric images.
Speaker 2: That's the smoking gun. It proves you're not just seeing
Speaker 2: some kind of optical artifact, you're visually confirming the physics.
Speaker 3: It validated the entire process. One of the co authors
Speaker 3: called it an extraordinary leap forward, and he's not wrong.
Speaker 3: We are now literally watching the material as it's blasted
Speaker 3: into space and connecting that directly to the physics of
Speaker 3: how it's happening. We've gone from theorizing about how shockwaves
Speaker 3: form to directly observing them form.
Speaker 2: And what that new window immediately showed was that the
Speaker 2: simple spherical model of a nova is well, it's just wrong.
Speaker 3: It's completely insfie.
Speaker 2: The team managed to image two novae that erupted in
Speaker 2: twenty twenty one, and they couldn't have been more different
Speaker 2: from each other. That variability is really the heart of
Speaker 2: this whole discovery.
Speaker 3: Absolutely, the contrast between these two novae, V one seventy
Speaker 3: before hercules and V fourteen oh five cassiopa is the
Speaker 3: direct evidence that's forcing us to rewrite the textbooks. We're
Speaker 3: seeing this incredible variety of ejection pathways.
Speaker 2: Which proves that the final shape isn't just about the
Speaker 2: energy of the blast, right, it.
Speaker 3: Must be highly dependent on other factors, like the white
Speaker 3: dwarf's rotation, or its magnetic field, or the shape of
Speaker 3: the material it's stealing.
Speaker 2: Okay, let's get into the first case, nova V one
Speaker 2: sits seventy four hercules. The sources described this one as
Speaker 2: one of the fastest stellar explosions ever recorded. What do
Speaker 2: we mean by fast.
Speaker 3: We mean blindingly fast. V one cs seventy four hercules
Speaker 3: peaked in brightness and then faded away in just a
Speaker 3: few days, just days, just a few days. A more
Speaker 3: typical nova might take weeks or even months to go
Speaker 3: through its whole cycle. So this rapid elevilution meant that
Speaker 3: the crucial early stages, the initial ejection of material, were
Speaker 3: all compressed into this tiny observational.
Speaker 2: Window, which makes the fact that they caught it with
Speaker 2: Chara even more incredible.
Speaker 3: It's a huge achievement. And what they saw in this
Speaker 3: first couple of days, I mean, the geometry is stunningly asymmetrical,
Speaker 3: not a sphere, not even close to his sphere. The
Speaker 3: images taken just two point two and three point two
Speaker 3: days after the explosion revealed the immediate formation of two
Speaker 3: distinct perpendicular outflows of gas.
Speaker 2: Perpendicular, so not just two jets shooting out from the poles,
Speaker 2: but two sets of jets at right angles to each other.
Speaker 3: That's what the data shows. We're talking about high speed
Speaker 3: jets of material shooting out almost at right angles. It's
Speaker 3: an incredibly complex shape to form so quickly.
Speaker 2: That implies the explosion's engine isn't uniform at all. What
Speaker 2: kind of physics could possibly drive flows like that.
Speaker 3: That's the million dollar question now, and it's probably tied
Speaker 3: to the system's rotation and magnetic fields. A rapidly spinning
Speaker 3: white dwarf can easily form a bipolar outflow, you know,
Speaker 3: two jets shooting from the poles.
Speaker 2: Right, That makes sense the path of least resistance.
Speaker 3: But perpendicular flows suggests something even more complex is going on,
Speaker 3: maybe a pre existing structure that the blast is hitting,
Speaker 3: or perhaps a rapidly tumbling or tilted magnetic field that's
Speaker 3: channeling the plasma in multiple directions at once.
Speaker 2: So this is direct visual evidence of multiple interacting ejections,
Speaker 2: not one single puff.
Speaker 3: That's the takeaway. And what's critical is that this complex
Speaker 3: geometry immediately explained the high energy data they were seeing
Speaker 3: at the same.
Speaker 2: Time, the gamma rays.
Speaker 3: The gamma rays the images from Shara showed these fast
Speaker 3: moving jets colliding with slower moving gas that was probably
Speaker 3: ejected just a little bit earlier. This violent collision is
Speaker 3: the perfect setup for generating intense shockwaves, and.
Speaker 2: We now know those shockwaves are the source of the
Speaker 2: gamma rays that NASA's Fermi Space telescope saw.
Speaker 3: It was direct, irrefutable proof the geometric complexity is driving
Speaker 3: the high energy physics.
Speaker 2: Okay, so that's one star that just rushed through its
Speaker 2: explosion with this specta tacular jet driven chaos. But then
Speaker 2: we look at the other one, nova V fourteen oh
Speaker 2: five Cassiopa, and it seems to be operating on a
Speaker 2: totally different schedule.
Speaker 3: V fourteen oh five Cassiopa was the polar opposite in
Speaker 3: many ways. It evolved much more slowly, which isn't unheard of.
Speaker 3: But the central surprise here was a clear, dramatic physical delay.
Speaker 3: This nova showed the first clear evidence of a delayed expulsion.
Speaker 2: A delay. What does that mean? The explosion happened, but
Speaker 2: the material didn't leave.
Speaker 3: Essentially, yes, the star held onto its outer layer's material
Speaker 3: for more than fifty days.
Speaker 2: Fifty so for almost two months. The thermonuclear runaway had
Speaker 2: already happened on the surface, but the material was just
Speaker 2: stuck there.
Speaker 3: That's right. The energy was generated, but the stellar envelope
Speaker 3: didn't fully disperse. It was contained somehow.
Speaker 2: That's incredible. I mean, the pressure from a runaway thermal
Speaker 2: pulse should be enormous and immediate. What could possibly hold
Speaker 2: it in for fifty days?
Speaker 3: It suggests there was some power full confining mechanism, perhaps
Speaker 3: an incredibly strong and compressed magnetic field acting like a
Speaker 3: cage trapping the plasma, or maybe an unusually dense initial
Speaker 3: envelope that needed a lot more sustained energy to finally
Speaker 3: overcome the star's gravity.
Speaker 2: Whatever the cause, the consequences when that containment finally failed
Speaker 2: must have been spectacular.
Speaker 3: They were. When the material was finally expelled after that
Speaker 3: fifty day confinement, it erupted violently. This triggered new incredibly
Speaker 3: intense shocks, like a spring that's been compressed for two
Speaker 3: months and is suddenly released.
Speaker 2: And I'm guessing fermisaw a burst of gamma rays from
Speaker 2: this one too, a huge.
Speaker 3: Burst of gamma rays, Yeah, which provided even more support
Speaker 3: for this shock driven model of high energy emission.
Speaker 2: So what's fascinating here is the sheer variability. You look
Speaker 2: at just two events and you get one that's immediate
Speaker 2: perpendicular jets and another that's a fifty day magnetic cage scenario.
Speaker 3: It completely shatters the idea of a standard nova. It
Speaker 3: tells us that the local environment, the white dwarf's magnetic field,
Speaker 3: it's spin, the density of the material, it's stealing all
Speaker 3: of that dictates the outcome. The geometry is everything, and
Speaker 3: the geometry is wildly diverse.
Speaker 2: So we have the visual proof of the geometry, We
Speaker 2: have the timeline of the ejection. Now we have to
Speaker 2: connect the docks. Why does seeing these structural details, the
Speaker 2: perpendicular jets, the fifty day delay, why does that matter
Speaker 2: so much to the broader field of high energy astrophysics.
Speaker 3: Because it directly solves a major puzzle from the last decade,
Speaker 3: which is where are all these high energy gamma rays
Speaker 3: in our galaxy coming from?
Speaker 2: We knew novae were one of the sources.
Speaker 3: Right before Shara, NASA's FIRMI Large Area Telescope had detected
Speaker 3: JIV emission that's gig electron BOLG gamma rays from more
Speaker 3: than twenty novae. This established them as significant galactic gamma
Speaker 3: ray factories.
Speaker 2: We knew the factory existed, but we didn't know how
Speaker 2: the machinery inside actually worked. We assumed it with shockwaves,
Speaker 2: but that was just a theory.
Speaker 3: It was a very strong theory, but it was still
Speaker 3: a theory. These new images provide the direct proof. They
Speaker 3: allow us to definitively tie the gamma rays seen by
Speaker 3: Fermi not to the initial flash, but directly to those
Speaker 3: colliding outflows.
Speaker 2: The visual structures are the engines creating the high energy
Speaker 2: radiation precisely.
Speaker 3: It's a remarkable piece of validation. If novae were truly spherical,
Speaker 3: those shockwaves would dissipate quickly and symmetrically. You probably wouldn't
Speaker 3: get such intense gamma rays. It's the fact that the
Speaker 3: ejecta are lumpy and messy and colliding that creates the
Speaker 3: perfect conditions for particle acceleration.
Speaker 2: This elevates novae from just being pretty fireworks in the galaxy.
Speaker 3: To being, as the Source Material calls them, laboratories for
Speaker 3: extreme physics. This is where we get to study how
Speaker 3: energy is transferred in the cosmos in a real world setting.
Speaker 2: I love that phrase. Let's dig into that. What do
Speaker 2: we mean when we say novae are labs for studying
Speaker 2: shock physics and particle acceleration. What's actually happening in those collisions.
Speaker 3: We're talking about natural particle accelerators that are far more
Speaker 3: powerful than anything we could build on Earth. The shockwaves
Speaker 3: from these collisions are incredibly efficient at scooping up charged particles, protons, electrons,
Speaker 3: and accelerating them to near the speed of light, and.
Speaker 2: This happens through a process called diffusive shock acceleration, or
Speaker 2: the Fermi mechanism.
Speaker 3: That's the one. The basic idea is that particles get
Speaker 3: trapped near the shock front and bounce back and forth
Speaker 3: across it repeatedly. It's like a cosmic pinball.
Speaker 2: Game, and with each bounce they gain energy.
Speaker 3: They get a kick of energy with every single pass,
Speaker 3: and they do this over and over rapidly accelerating until
Speaker 3: they have enough energy to produce gamma rays, which are
Speaker 3: the highest energy form of light.
Speaker 2: And because Chara gives us the precise visual of when
Speaker 2: the collisions happen and what the shape of the colliding
Speaker 2: material is, we can now test our models of that
Speaker 2: acceleration process with real data.
Speaker 3: That's the key. Before these models were mostly tested in
Speaker 3: much bigger and much messier systems like supernova remnants. Nov
Speaker 3: are smaller, they happen much more frequently in our own galaxy,
Speaker 3: and they evolve faster, which makes them fantastic accessible laboratories.
Speaker 2: So this isn't just about understanding one type of stellar explosion.
Speaker 2: It's about fundamental physics.
Speaker 3: It's about the origin of cosmic rays. It's about how
Speaker 3: particles get energized throughout the universe, and it all comes
Speaker 3: back to challenging that long held view that nova eruptions
Speaker 3: are simple single events. That model is dead.
Speaker 2: So if we connect this to the bigger picture, this
Speaker 2: means we can finally draw a direct cohesive line all
Speaker 2: the way from the nuclear reactions on the star's surface.
Speaker 3: The geometry of the material flows that result.
Speaker 2: From it, and finally to the high energy gamma rays
Speaker 2: that are produced by those flows. It's the whole chain
Speaker 2: of events observed from start.
Speaker 3: To finish exactly. It's linking the microphysics of the surface
Speaker 3: to the macrophysics of the shockwaves and the ultra high
Speaker 3: energy output. This reshapes our models of how even relatively
Speaker 3: small stellar events like novae contribute to the energetic budget
Speaker 3: of the Milky Way.
Speaker 2: It's taken hypothesis and turning it into observed, tested reality.
Speaker 2: Knowing the gamma rays come from shock is one thing,
Speaker 2: but actually seeing the messy jets and delayed explosions that
Speaker 2: create those shocks. That's the ultimate confirmation, and.
Speaker 3: It means we can start asking much more specific questions.
Speaker 3: We can use the geometry to infer things about the
Speaker 3: white dwarf's rotation speed, its magnetic field, and the accretion rate,
Speaker 3: all of which drive these dramatic and varied explosions.
Speaker 2: This has been incredible, going from the weirdness of electron
Speaker 2: degeneracy pressure all the way to aligning light beams with
Speaker 2: a nanometer precision. We've gone from seeing novae as these
Speaker 2: simple flashes to understanding them as these complex, geometrically rich events.
Speaker 3: You have the immediate perpendicular jets of V sixteen seventy
Speaker 3: four hercules on one.
Speaker 2: Hand, and on the other you have the dramatic fifty
Speaker 2: day delayed eruption of V fourteen oh five cassiophs, completely
Speaker 2: different beasts, and.
Speaker 3: We have to remember this is just the beginning. The
Speaker 3: lead author of the study set as much the fact
Speaker 3: that they found such complex and varied shapes in just
Speaker 3: their first two detailed observations suggest the field is wide open.
Speaker 2: There's probably a whole zoo of other shapes and behaviors out.
Speaker 3: There, a whole zoo. With more observations, scientists can start
Speaker 3: answering the really big questions about the diverse ways stars
Speaker 3: shed their mass and influence the universe around them.
Speaker 2: The era of the unresolved point of light is definitely over.
Speaker 2: Novae which we once thought were pretty straightforward, are now
Speaker 2: revealed to be so much richer and more fascinating than
Speaker 2: we ever imagined, and that fascination really leads us to
Speaker 2: our final thought for you with the learner think about it.
Speaker 3: We observe two novae, just two, and they displayed wildly
Speaker 3: different behaviors. One was fast with perpendicular flows, likely driven
Speaker 3: by rotation or magnetism.
Speaker 2: And the other was a slow burn a fifty day delay,
Speaker 2: probably caused by some kind of magnetic cage.
Speaker 3: The fact that you see such extreme variability in a
Speaker 3: statistical sample of two will that suggests that the cosmos
Speaker 3: is holding a huge number of geometrical surprises for us.
Speaker 2: So if the universe showed us two fundamentally different ways
Speaker 2: for a star to explode right out of the gate,
Speaker 2: what other unexpected scene and maybe even bizarre mechanisms are
Speaker 2: out there.
Speaker 3: Could we see corkscrewing jets, or episodic stuttering bursts, or
Speaker 3: maybe three way collisions from a truly chaotic magnetic field.
Speaker 3: We just don't know.
Speaker 2: The stellar physics textbooks are clearly due for a major rewrite,
Speaker 2: and we'll be watching these guys right alongside the Cheera
Speaker 2: team to find out what new chapter they uncover next.
Speaker 3: The Nassai