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: I want you to just close your eyes for a second.
Speaker 2: Try to imagine the absolute most extreme environment you can
Speaker 2: possibly conceive of. Oh wow, okay, yeah, And I don't
Speaker 2: just mean like a place that's uncomfortably hot. I want
Speaker 2: you to picture an entirely different physical reality.
Speaker 3: Right, like completely alien exactly.
Speaker 2: Imagine you're standing on a shoreline, but the ocean stretching
Speaker 2: out in front of you, it isn't made of water.
Speaker 2: It is this vast, churning sea of molten silicate rock,
Speaker 2: just glowing this deep orange in the dark.
Speaker 3: That is terrifying it is.
Speaker 2: And you look up and the sky isn't blue, It's
Speaker 2: this thick, suffocating, opaque haze. And the smell, the smell
Speaker 2: of the air around you is just punishingly toxic. It's
Speaker 2: overwhelmingly dominated by the scent of rotting eggs.
Speaker 3: It is a literal sensory nightmare. I mean, it's a
Speaker 3: hellscape of the highest order where the very concept of
Speaker 3: a solid surface basically ceases to exist.
Speaker 2: It really does. But the crazy thing is we are
Speaker 2: talking about a very real place. It's a super earth
Speaker 2: known as L ninety eight fifty nine DY, which.
Speaker 3: Is about thirty five light years away from us, right, yeah,
Speaker 3: the constellation Vila.
Speaker 2: Yeah, exactly thirty five light years. But we aren't going
Speaker 2: on a mental journey to this world today just for
Speaker 2: the novelty of, you know, looking at a bizarre, stinky planet.
Speaker 3: No, definitely not. There's a much bigger reason, right, We.
Speaker 2: Are looking at this specific world because it actually happens
Speaker 2: to be the smoking gun that solves one of the
Speaker 2: most frustrating cold cases in modern astronomy.
Speaker 3: Oh absolutely, it's a total game changer.
Speaker 2: So before we even talk about the molten notions or
Speaker 2: the toxics guy, we kind of need to set the
Speaker 2: stakes for you because for years planetary scientists have basically
Speaker 2: been staring at this massive glaring hole in our map
Speaker 2: of the galaxy.
Speaker 3: Yeah, the Radius Valley, or some people call it the
Speaker 3: Fulton Gap that was the original name when the Kepler
Speaker 3: Space telescope data first brought it to light, the Fulton Gap,
Speaker 3: and it is one of the most profound mysteries in
Speaker 3: exoplanet demographics. I mean, when you plot out every single
Speaker 3: small exoplanet we have ever discovered on a graph, just
Speaker 3: based on their physical size, you expect to see relatively
Speaker 3: smooth distribution like a Bell curve, right exactly like a
Speaker 3: Bell curve, or maybe you know, a steady drop off
Speaker 3: as planets get larger and harder to form.
Speaker 2: But instead the graph looks, well, it looks like a
Speaker 2: mountain range with this massive canyon carved right down the
Speaker 2: middle of it.
Speaker 3: It's so weird, it really is a canyon.
Speaker 2: Yeah. So we see this huge peak of rocky planets
Speaker 2: that are about the size of Earth up to maybe
Speaker 2: like one point four times Earth's radius, right the terrestrial worlds,
Speaker 2: and then further down the graph we see another huge
Speaker 2: peak of planets that are bigger around two to three
Speaker 2: times Earth's radius.
Speaker 3: The mini Neptunes. Those are the ones with thick, puffy atmospheres.
Speaker 2: AGAs exactly, but right in the middle between one point
Speaker 2: five and two times the size of Earth. The population
Speaker 2: of planets just absolutely plummet.
Speaker 3: It's complete dead zone.
Speaker 2: It's just empty.
Speaker 3: Yeah, the planets simply go missing in that size bracket.
Speaker 3: And the thing is, it is statistically impossible for that
Speaker 3: gap to be an accident of our observation methods.
Speaker 2: Like, it's not just a glitch in the telescopes.
Speaker 3: No, not at all. The universe is actively preventing planets
Speaker 3: from staying in that specific size range. Or and this
Speaker 3: was the leading idea, it's rapidly stripping them down so
Speaker 3: they fall into the smaller category.
Speaker 2: Right, So the leading theory for a long time was atmospheric.
Speaker 4: Loss yep photo evaporation, the idea being that a planet
Speaker 4: might form with a thick hydrogen envelope, which puts it
Speaker 4: in that larger mini neptune category, but if it orbits
Speaker 4: too close to its host star, the.
Speaker 3: Intense radiation just eventually boils that atmosphere away.
Speaker 2: It boils away, the planet shrinks, crosses that forbidden zone
Speaker 2: of the radius valley really quickly. It ends up just
Speaker 2: a bare, rocky core on the other.
Speaker 3: Side, exactly. And so the assumption for decades was that
Speaker 3: planetary evolution is fundamentally a story of subtractions attraction.
Speaker 2: Right, you start big, the star strips you, you end
Speaker 2: up small.
Speaker 3: It was this really neat binary framework. Path one you
Speaker 3: somehow hold onto your gas, maybe you're far enough away
Speaker 3: from the star and you stay a mini neptune. And
Speaker 3: path two, Path two is your star strips you naked
Speaker 3: and you become a bare rock, which.
Speaker 2: Is so intuitive it makes perfect physical sense.
Speaker 3: It does, especially based on how aggressive we know young
Speaker 3: stars can be, particularly the en dwarfs, the red dwarf stars.
Speaker 2: And those are the most common stars in our galaxy.
Speaker 3: Right by far, and they are notorious for violent stellar
Speaker 3: flares and this intense extreme ultraviolet radiation that basically acts
Speaker 3: like a blow torch on planetary atmosphere.
Speaker 2: A blow to That's a great way to put it,
Speaker 2: which brings us back to our target. L ninety eight
Speaker 2: fifty nine D yes the rule breaker.
Speaker 3: Because this specific planet, in this specific star system just
Speaker 3: completely breaks that binary framework. It literally forces us to
Speaker 3: rewrite the fundamental physics of how planets evolve and survived.
Speaker 2: It really does, and the whole unraveling of this mystery,
Speaker 2: it actually started with a cosmic weight problem.
Speaker 3: A weight problem. I love that the severe density anomaly.
Speaker 2: Right, so L ninety eight fifty nine D was first
Speaker 2: discovered back in twenty nineteen by NASA's Tests satellite.
Speaker 3: Tests the Transiting Exoplanet Survey.
Speaker 2: Satellite exactly and tests uses the transit photometry method. It
Speaker 2: basically stares at a patch of sky and just waits
Speaker 2: for a star's light to.
Speaker 3: Dim just a tiny fraction of a percent, right, Yeah,
Speaker 3: a microscopic dip in light, and that indicates that a
Speaker 3: planet has crossed in front of it. And based on
Speaker 3: how much light is blocked, we can calculate the physical
Speaker 3: volume the size of the planet, and.
Speaker 2: Test told us that L ninety eight to fifty nine
Speaker 2: DY is roughly one point six times the size.
Speaker 3: Of Earth, which drops it squarely into the danger zone
Speaker 3: right in the middle of a canyon. It's sitting right
Speaker 3: on the edge of that forbidden radius valley. It is
Speaker 3: in the transition zone.
Speaker 2: But just knowing the physical volume of a planet is
Speaker 2: only the first step.
Speaker 3: Right, to understand what a planet is actually made of,
Speaker 3: you need its mass.
Speaker 2: You need to weigh it exactly.
Speaker 3: And for that astronomers use ground based spectrographs to measure
Speaker 3: the radial velocity. That's the tiny, tiny gravitational wobble. The
Speaker 3: planet induces on its host star.
Speaker 2: So the planet pulls on the star.
Speaker 3: A little bit. It does, and when you have the
Speaker 3: volume from the transit and you have the mass from.
Speaker 2: The wobble, you can calculate the overall bulk density.
Speaker 3: BINGO, and the density of L ninety eight to fifty
Speaker 3: nine D immediately set off alarm bells for everyone looking
Speaker 3: at the data.
Speaker 2: Because if you have a planet that's one point six
Speaker 2: times the size of Earth and it's sitting incredibly close
Speaker 2: to its host star, you expect a very specific composition.
Speaker 3: You really do. The radiation environment is so brutal there
Speaker 3: that any primordial fluffy envelope of hydrogen and helium it
Speaker 3: should have been photo evaporated away billions of years ago.
Speaker 2: So you expect to find a dense, bare terrestrial rock
Speaker 2: like an iron core surrounded by a solid silicate mantle, right.
Speaker 3: But the radio velocity measurements revealed something entirely different. The
Speaker 3: mass of the planet was just far, far too low
Speaker 3: for its physical.
Speaker 2: Size, so it's huge, but it's really light.
Speaker 3: The density was abnormally low. It was much lighter than
Speaker 3: a pure rocky world of that diameter.
Speaker 2: Should ever be Okay, let's unpack this for a second.
Speaker 2: It's like it's like picking up a bowling ball right
Speaker 2: and expecting it to be super heavy, but you realize
Speaker 2: it weighs as much as a styrofoam block.
Speaker 3: That is a perfect analogy.
Speaker 2: Your brain immediately knows something is just fundamentally wrong with
Speaker 2: the recipe. The math just doesn't add up.
Speaker 3: It really doesn't. You have this massive volume but missing mass. Wow,
Speaker 3: And the traditional models they basically leave you with two
Speaker 3: options for a low density world.
Speaker 2: Okay, what's option A.
Speaker 3: Option eight is the gas dwarf scenario. We just discussed
Speaker 3: a small rocky with a huge, puffy hydrogen atmosphere.
Speaker 2: Well, we already ruled that out right exactly.
Speaker 3: We ruled it out because the red dwarf's high energy
Speaker 3: X ray and UV emissions would have stripped a lightweight
Speaker 3: hydrogen atmosphere away eons ago.
Speaker 2: I mean, the system is five billion years old. A
Speaker 2: primordial hydrogen envelope simply cannot survive there.
Speaker 3: It's physically impossible. The stellar wind would act like a
Speaker 3: sand blaster over those timescales. The retention of a primordial
Speaker 3: envelope at that orbital distance is just untenable.
Speaker 2: Okay, so option A is out. That leaves option B
Speaker 2: for a low density planet, the water world.
Speaker 3: Right, the water world.
Speaker 2: A planet with a smaller rocky core, but it's enveloped
Speaker 2: by this massive, deep ocean of liquid water, or maybe
Speaker 2: an incredibly thicked shell of high pressure ice.
Speaker 3: And that makes sense on paper because water is significantly
Speaker 3: less dense than iron and silicate rock.
Speaker 2: So incorporating a huge fraction of water into the planet's
Speaker 2: bulk composition perfectly explains the missing mass. Right. It expands
Speaker 2: the volume without adding heavy metals.
Speaker 3: It solves the density equation beautifully.
Speaker 2: But there's always a butt.
Speaker 3: There's always a butt. In astronomy, the problem is the
Speaker 3: thermodynamic reality of the planet's orbit. L ninety eight fifty
Speaker 3: nine D is tuck in so incredibly close to its
Speaker 3: star that the stellar irradiation it receives is just astronomical.
Speaker 2: Oh right, We're talking surface temperatures estimated around nineteen hundred
Speaker 2: degrees celsius.
Speaker 3: Over thirty five hundred degrees fahrenheit.
Speaker 2: Liquid water cannot exist in that regime, not even close.
Speaker 3: No way. I mean, even if the planet had somehow
Speaker 3: formed further out in the star system, like beyond the
Speaker 3: snow line and then migrated inward over millions of years.
Speaker 2: Water wouldn't stick around, it would.
Speaker 3: Not remain stable. It would vaporize into this massive steam atmosphere,
Speaker 3: and water vapor in the upper atmosphere is highly susceptible
Speaker 3: to photoed association.
Speaker 2: Wait, photo association explain that process.
Speaker 3: Basically, the intense UV light from the red dwarf would
Speaker 3: act like a hammer. It would literally shatter the water
Speaker 3: molecules apart in to hydrogen and oxygen.
Speaker 2: Oh wow, so it just breaks the water apart exactly.
Speaker 3: The lighter hydrogen escapes into space, the heavier oxygen falls
Speaker 3: down and oxidizes the crust, and eventually the entire planet desiccates.
Speaker 2: It just rusts and dries out completely if the dead end.
Speaker 2: So it can't be rock because it's too light, right.
Speaker 2: It can't be a gas dwarf because the stellar wind
Speaker 2: would strip the hydrogen right again. And it can't be
Speaker 2: a water world because the temperature would boil the oceans
Speaker 2: and the star would shatter the steam exactly. So what
Speaker 2: is it? I mean? The planetary science community was essentially
Speaker 2: looking at a ghost. Something was taking up a massive
Speaker 2: amount of physical space around that rocky core, puffing the
Speaker 2: planet's volume up to one point six earth radii.
Speaker 3: But resisting the blow torch of the red dwarf star
Speaker 3: for five billion years. It's just wild.
Speaker 2: How do you even begin to solve that?
Speaker 3: Well, honestly, it was an intractable problem with the observatories
Speaker 3: we had available in twenty nineteen.
Speaker 2: Because we only had tests and ground based telescopes.
Speaker 3: Right, we could measure sure the bulk parameters, you know,
Speaker 3: the mass and the radius. Yeah, but those numbers only
Speaker 3: offered contradictory boundary conditions.
Speaker 2: They just told us what it could be exactly.
Speaker 3: To figure out what was actually inflating this planet, we
Speaker 3: had to stop looking at its gravitational footprint and start
Speaker 3: looking directly at its chemistry.
Speaker 2: We needed to read the chemical bar code of whatever
Speaker 2: envelope was clinging to this.
Speaker 3: World, which requires transmissions Pictrosky.
Speaker 2: And doing that on a small, rocky super Earth thirty
Speaker 2: five light years away, I mean, that is an entirely
Speaker 2: different ballgame than looking at a giant, puffy hot Jupiter.
Speaker 3: Oh, it's exponentially harder. The atmospheric signal you were trying
Speaker 3: to isolate is microscopic. The scale of the measurement is.
Speaker 2: Just staggering right, because when L ninety eight to fifty
Speaker 2: nine D transits its host star, the solid body of
Speaker 2: the planet blocks a fraction of the.
Speaker 3: Starlight, but the atmosphere, assuming it even has one, is
Speaker 3: just a razor thin halo around that solid sphere.
Speaker 2: Okay, I have an analogy for this. To visualize this,
Speaker 2: I want you to imagine holding up a thick piece
Speaker 2: of stained glass to a blindingly bright searchlight.
Speaker 3: Oh, I like this.
Speaker 2: So the solid metal frame of the glass blocks the
Speaker 2: light entirely right, It casts a hard shadow, but the
Speaker 2: translucent colored glass lets a tiny, tiny fraction of that
Speaker 2: search light bleed through.
Speaker 3: Yep.
Speaker 2: And if you stand far enough back and analyze the
Speaker 2: exact wavelengths of light that make it through the glass,
Speaker 2: you can reverse engineer the chemical dyes used to color it.
Speaker 3: Because certain chemicals absorb red light and others absorb blue.
Speaker 2: Exactly, the missing colors tell you the composition of the barrier.
Speaker 3: That is precisely the essence of transmission spectroscopy. It's so cool,
Speaker 3: it really is. As the starlight from the red dwarf
Speaker 3: filters through the incredibly thin atmospheric limb of L ninety
Speaker 3: eight fifty nine D. The specific molecules suspended in that
Speaker 3: alien air act as chemical filters.
Speaker 2: Just like the stained glass.
Speaker 3: Exactly like the stained glass, they absorb very specific, quantifiable
Speaker 3: wavelengths of infrared light.
Speaker 2: And to see that, we needed a serious upgrade in
Speaker 2: our tech.
Speaker 3: We need it the James Webb Space Telescope. When JWST
Speaker 3: captures that filtered starlight, its near infrared spectram graph in
Speaker 3: iro spec disperses the light into a high resolution spectrum,
Speaker 3: and we just looked for the absorption.
Speaker 2: Bands, the missing slivers of light.
Speaker 3: Missing slivers exactly, and this signal.
Speaker 2: To noise ratio required to detect those missing slavers on
Speaker 2: a planet this small. I mean, that's literally why we
Speaker 2: had to wait for a ten billion dollar Berrillium Mirror
Speaker 2: observatory parked a million miles from Earth.
Speaker 3: Previous telescopes just didn't have the sensitivity in the infrared
Speaker 3: to see through the glare of the host star. JWFT
Speaker 3: represents a total paradigm shift to our diagnostic capabilities.
Speaker 2: So what happened when they actually pointed JWST at it.
Speaker 3: Well, the international team led by researchers at the University
Speaker 3: of Oxford, they pointed jawst at this system analyze the
Speaker 3: transmission spectrum, and the absorption features that popped out of
Speaker 3: the data were entirely unexpected.
Speaker 2: Like they didn't find the lightweight signatures of primordial hydrogen
Speaker 2: and helium Nope, none, And they didn't find a saturated
Speaker 2: signal of water vapor right right.
Speaker 3: What they found were profound undeniable absorption bands corresponding to
Speaker 3: heavy sulfur compounds sulfur specifically sulfur dioxide and hydrogen sulfide.
Speaker 2: Hydrogen sulfide. Okay, here's where it gets really interesting. For
Speaker 2: anyone who has ever been near a geyser or a
Speaker 2: volcanic vent or you know, simply smelled or rotting egg.
Speaker 3: You know the visceral impact of hydrogen sulfide.
Speaker 2: It is a highly toxic, incredibly pungent gas. Finding it
Speaker 2: out in the cosmos isn't necessarily strange, right, Like we
Speaker 2: see sulfur in planetary nebulas and young star forming regions.
Speaker 3: Sure, sulfur is common, but finding it dominating the thick
Speaker 3: atmosphere of a blazing hot super Earth that changes the
Speaker 3: entire physical model of the planet.
Speaker 2: Because it immediately resolves the density anomaly.
Speaker 3: It does, but and this is a big butt. It
Speaker 3: introduces a severe dynamic paradox.
Speaker 2: Okay, let's break that down. How does it resolve the density?
Speaker 3: Well, a heavily metallic, volatile rich atmosphere like one dominated
Speaker 3: by sulfur to oxide and hydrogen sulfide has a much
Speaker 3: higher mean molecular weight than a hydrogen helium envelope.
Speaker 2: So it's heavier, it's denser.
Speaker 3: It's denser, it hugs the planet tighter, and it is
Speaker 3: significantly harder for the stellar wind to strip away.
Speaker 2: It's like wearing heavier armor. It resists the photo of
Speaker 2: operation blow towards much better than fluffy hydrogen exactly.
Speaker 3: And the sheer volume of this thick, heavy, hazy sulfur
Speaker 3: envelope explains why the planet is puffed up to one
Speaker 3: point six times the size of Earth without adding the
Speaker 3: mass of solid rock.
Speaker 2: So the static math works. The puzzle pieces finally fit together.
Speaker 3: The static math works, Yes, but planetary atmospheres are not static,
Speaker 3: especially not in a compact orbit around a red dwarf.
Speaker 2: Right, because even with the heavier molecular weight of sulfur
Speaker 2: compounds the extreme ultraviolet radiation and the relentless stellar wind
Speaker 2: over five billion years, it would still inexorably erode that atmosphere.
Speaker 3: It might be harder to strip than hydrogen, but over
Speaker 3: billions of years, it should still be gone.
Speaker 2: It has to be bleeding into space. The physics of
Speaker 2: the stellar wind literally demand it.
Speaker 3: They do. Therefore, the fact that JWST observes a thick,
Speaker 3: opaque sulfur envelope today, five billion years into the system's lifespan,
Speaker 3: implies a terrifying reality. The atmosphere is not a primordial remnant.
Speaker 3: It is not a leftover shell of gas from the
Speaker 3: planet's berth. It is being actively, aggressively and continuously replenished.
Speaker 2: Wow, so the planet is bleeding sulfur into the sky
Speaker 2: faster than the star can strip it away.
Speaker 3: Exactly. It is a planetary scale out gassing engine.
Speaker 2: And to fuel an engine that massive, to continuously pump
Speaker 2: millions of tons of hydrogen, sulfide and sulfur dioxide into
Speaker 2: the atmosphere for five eons, you need a reservoir of
Speaker 2: unthinkable proportions.
Speaker 3: Right. You can't just have a few active volcanoes dotting
Speaker 3: a solid crust. That wouldn't cut it.
Speaker 2: A localized volcanic network would exhaust its volatile supply way
Speaker 2: too quickly.
Speaker 3: Far too quickly, And that's where the geodynamic simulations come in.
Speaker 3: The model presented in the March twenty twenty six Nature
Speaker 3: Astronomy paper takes the jawst atmospheric data and couples it
Speaker 3: with interior geodynamic simulations.
Speaker 2: They basically calculated what kind of internal structure is actually
Speaker 2: required to sustain this level of outgassing, and.
Speaker 3: The simulations converged on a singular extreme structural model.
Speaker 2: The permanent magma ocean.
Speaker 3: A global, deep seated layer of molten silicate rock.
Speaker 2: And we aren't just talking about a surface phenomenon right now.
Speaker 3: No, No. The nineteen hundred degree surface temperature guarantees that
Speaker 3: the crust itself is a glowing liquid. Sure, but the
Speaker 3: simulations dictate that this molten state extends thousands of kilometers
Speaker 3: deep into the planet's mantle.
Speaker 2: Okay, wait, I want to pause here and really dig
Speaker 2: into the geophysics, because when you say the word ocean,
Speaker 2: the human brain immediately defaults to the mechanics of water.
Speaker 3: Of course, you picture waves, right.
Speaker 2: We picture a sloshing fluid sphere, but a magma ocean
Speaker 2: extending thousands of kilometers down into a super Earth involves
Speaker 2: pressure regimes that fundamentally alter how matter behaves, oh completely.
Speaker 2: So how does a planet maintain its structural integrity if
Speaker 2: half of its volume is essentially a liquid like Why
Speaker 2: doesn't the tidal stress or the centrifugal force of its
Speaker 2: rotation just tear it apart into space?
Speaker 3: That is a great question. It comes down to the
Speaker 3: concept of reology. Reology, Yeah, reology the study of how
Speaker 3: matter flows under pressure. As you descend into the interior
Speaker 3: of L ninety eight fifty nine D, the gravitational pressure
Speaker 3: increases exponentially.
Speaker 2: Because there's so much weight pressing down from above.
Speaker 3: Exactly so, even though the temperature is high enough to
Speaker 3: melt silicate rock at the surface, the immense pressure at
Speaker 3: depth actively combats that melting.
Speaker 2: Because pressure forces atoms together, fighting the thermal energy that
Speaker 2: is trying to spread them apart.
Speaker 3: Spot on, and the result is a state of matter
Speaker 3: that is partially molten. It isn't a low viscosity liquid
Speaker 3: like water. The mantle is often described in these high pressure,
Speaker 3: high temperature regimes.
Speaker 2: As a mush, a mush that sounds unappealing.
Speaker 3: It behaves more like an unimaginably dense, glowing molasses.
Speaker 2: Glowing molasses. Okay, that's a brilliant visual.
Speaker 3: It flows, it convects, it churns, but it possesses enough
Speaker 3: viscosity and structural cohesion, bound by the immense gravity of
Speaker 3: the core, to maintain a perfect spherical shape.
Speaker 2: So the planet is essentially a giant convecting sphere of
Speaker 2: ultra pressurized, mushy liquid rock. Yes, but how does this
Speaker 2: molten state solve the sulfur problem? Like, how does glowing
Speaker 2: molasses act as a reservoir for toxic.
Speaker 3: Gas because magma is an incredibly efficient solvent for volatiles.
Speaker 2: A solvent.
Speaker 3: Okay, think back to when this planet was forming from
Speaker 3: the protoplanetary disc five billion years ago. It created a
Speaker 3: huge inventory of building blocks, dust, rock, and massive amounts
Speaker 3: of volatile elements like sulfur, hydrogen, carbon.
Speaker 2: And oxygen, all smashed together.
Speaker 3: Right now, if the planet had cooled down and solidified
Speaker 3: like Earth or like Venus, what would have happened to
Speaker 3: those volatiles.
Speaker 2: Well, solidification forces volatiles out of the crystal lattice of
Speaker 2: the rock. Right as magma crystallizes into solid stone, the
Speaker 2: gases are expelled.
Speaker 3: Exactly, they bubble up to the surface in a massive
Speaker 3: initial pulse of out gassing, forming a thick primordial atmosphere.
Speaker 2: And then the red dwarf star hits that atmosphere with
Speaker 2: its X ray blowtorch, strips it entirely and leaves behind
Speaker 2: a dead, solid barren rock.
Speaker 3: The path two scenario we talked about earlier, the fast
Speaker 3: track cross the redisalid if L.
Speaker 2: Ninety eight fifty nine did never solidified.
Speaker 3: It never solidified because it remained a deep, churning magma ocean.
Speaker 3: The crystallization process never completed. The magma ocean acts as
Speaker 3: a planetary scale.
Speaker 2: Sponge, a sponge for the gas.
Speaker 3: It traps the volatile elements, the sulfur and the hydrogen
Speaker 3: in solution deep within the liquid silicate melt. The magma
Speaker 3: physically holds onto the gases.
Speaker 2: Okay, it's like a sealed bottle of sparkling water. The
Speaker 2: carbon dioxide is trapped in the liquid. You can't see
Speaker 2: the gas, but it's held in solution by the pressure.
Speaker 3: That is exactly it. And as the magma slowly convects,
Speaker 3: hotter material from deep within the planet rises toward the surface,
Speaker 3: where the pressure is slightly lower.
Speaker 2: The solubility of the magma decreases, it can no longer
Speaker 2: hold as much gas.
Speaker 3: The bottle is uncapped. Boom the magma to gases. The
Speaker 3: sulfur and hydrogen bubble out of the glowing molasses, rising
Speaker 3: through the thousands of kilometers of molten mantle and continuously
Speaker 3: erupt into the atmosphere.
Speaker 2: It is a slow, steady, relentless release, A billion year exhalation,
Speaker 2: A billion year exhalation.
Speaker 3: I love that.
Speaker 2: And that is the planetary engine. The star is constantly
Speaker 2: scraping the top of the atmosphere away into the void,
Speaker 2: but the deep magma ocean is constantly burping up a
Speaker 2: fresh supply of hydrogen sulfide from the bottom to replace it.
Speaker 3: It's an equilibrium, a beautifully brutal equilibrium.
Speaker 2: But wait, this entire engine, this whole paradigm of Path
Speaker 2: three evolution. It relies on one foundational requirement, doesn't.
Speaker 3: It It does. The mantle must remain liquid. The outgassing
Speaker 3: stops the exact moment the planet freezes solid.
Speaker 2: Which brings us to the thermodynamics of the system. Because
Speaker 2: five billion years is a phenomenally long time to keep
Speaker 2: a rocky planet completely melted.
Speaker 3: It really is.
Speaker 2: I mean even sitting close to a star. Space is
Speaker 2: an infinite heat sink. The planet is constantly radiating thermal
Speaker 2: energy into the void. It should have cooled, crystallized, and
Speaker 2: dyed eons ago.
Speaker 3: It absolutely should have to keep an.
Speaker 2: Engine running for five billion years. You need an incredible
Speaker 2: continuous power source. You need a perfect storm of heat.
Speaker 3: And the nature. Astronomy researchers model the heat budget of
Speaker 3: L ninety eight fifty nine D extensively to figure out
Speaker 3: how this is possible and what did they find. They
Speaker 3: found that a single heat source is simply insufficient to
Speaker 3: maintain a mantle deep magma ocean over geological time scales.
Speaker 3: It requires a trifecta.
Speaker 2: A trifecta three distinct intersecting pillars of thermal energy working
Speaker 2: in concert. Okay, let's dissect the heat budget. Pillar one
Speaker 2: is the primordial heat of accretion, right, the violent birth
Speaker 2: of the planet.
Speaker 3: Yes, the kinetic energy d of planetary formation is immense.
Speaker 3: When planetesimals and protoplanetary chunks smashed together under the force
Speaker 3: of gravity to form a super Earth, all.
Speaker 2: That kinetic energy is converted into thermal energy. The entire
Speaker 2: mass of the newly formed planet is superheated.
Speaker 3: It starts its life as a literal ball of liquid fire.
Speaker 3: And for a planet one point six times the size
Speaker 3: of Earth, the sheer volume of material means it takes
Speaker 3: a very long time for that initial primordial heat to
Speaker 3: radiate away into space.
Speaker 2: Because the core is heavily insulated by the thousands of
Speaker 2: kilometers of rock above it.
Speaker 3: Right, and radiogenic heating also plays a minor role here.
Speaker 3: You know, the decay of radioactive isotopes deep in the.
Speaker 2: Core sure like a slow nuclear reactor.
Speaker 3: But even combined with the primordial heat, the models show
Speaker 3: it is not enough. Left entirely to its own devices,
Speaker 3: a super Earth of this mass would eventually form a
Speaker 3: solid lithosphere, a crust.
Speaker 2: Would form, the mantle would stiffen into solid rock, and
Speaker 2: the outgassing would shoke to a halt.
Speaker 3: So the planet needs insulation to slow down that cooling process.
Speaker 2: And it needs an active heater to inject new energy
Speaker 2: into the system.
Speaker 3: Yes, so the insulation is pillar two. The atmospheric greenhouse.
Speaker 2: Effect, the sulfur greenhouse because the sulfur rich atmosphere we
Speaker 2: detected with JWST isn't just a byproduct of the magma ocean.
Speaker 2: It is its protector exactly.
Speaker 3: I mean, we understand the greenhouse effect on Earth, right, yeah,
Speaker 3: trace amounts of carbon dioxide methane trapping the infrared radiation
Speaker 3: trying to escape the surface.
Speaker 2: But the greenhouse effect on l ninety eight fifty nine
Speaker 2: D is operating on a fundamentally different scale.
Speaker 3: A completely different scale. We are talking about a thick,
Speaker 3: opaque haze of heavy sulfur dioxide and hydrogen sulfide. It
Speaker 3: acts as an extreme heavy duty thermal blanket.
Speaker 2: So as the primordial heat from the deep interior slowly
Speaker 2: conducts its way to the surface ocean of lava, it
Speaker 2: tries to radiate into space, but the.
Speaker 3: Sulfur blanket intercepts that infrared energy, absorbs it, and radiates
Speaker 3: it back down toward the surface.
Speaker 2: It creates a thermal feedback loop.
Speaker 3: It does. The magma out gases the sulfur. The sulfur
Speaker 3: forms the atmospheric blanket, and the blanket traps the heat
Speaker 3: required to keep the magma liquid so it can continue
Speaker 3: out gassing.
Speaker 2: That is an incredible symbiotic relationship. It's almost biological in
Speaker 2: its elegance.
Speaker 3: It really is. Again, but even the best thermal blanket
Speaker 3: in the universe eventually loses heat. A blanket doesn't generate energy,
Speaker 3: it only delays its escape.
Speaker 2: Right, you don't warm up a cold bed just by
Speaker 2: throwing a blanket on it.
Speaker 3: Exactly, to keep a thousands of kilometers deep ocean of
Speaker 3: rock molden for five billion years, you absolutely must have
Speaker 3: an active heater plugged into the wall.
Speaker 2: You need a mechanism that physically injects new thermal energy
Speaker 2: into the planet's interior.
Speaker 3: And this is where the orbital dynamics of the L
Speaker 3: ninety eight to fifty nine system become the critical key
Speaker 3: to the entire mystery. This brings us to pillar three,
Speaker 3: tidal heating.
Speaker 2: Tidal heating. Now, when we say tides, we have to
Speaker 2: strip away the terrestrial bias for a second. We aren't
Speaker 2: talking about the Moon gently pulling on the oceans to
Speaker 2: give us high tide the beach.
Speaker 3: No. No, we are talking about gravitational forces so profound
Speaker 3: they physically deform the solid structure of the planet.
Speaker 2: Because L ninety eight fifty nine is not a lonely
Speaker 2: star system, it is a compact multiplanet system.
Speaker 3: There are at least four planets crammed into orbits that
Speaker 3: are incredibly close to the host star, they are orbiting
Speaker 3: in a tight, crowded.
Speaker 2: Neighborhood, and because they are so close to each other,
Speaker 2: their gravitational fields interact constantly right constantly.
Speaker 3: The host star has a massive gravitational grip on L
Speaker 3: ninety eight fifty nine D, locking it in a tight orbit.
Speaker 3: But as the other planets in the system race around
Speaker 3: the star on their own orbits, they constantly pass by
Speaker 3: L ninety eight fifty nine D.
Speaker 2: And every time a neighboring planet swings past its gravity
Speaker 2: tugs on our super Earth.
Speaker 3: It pulls it slightly out of a perfect circular orbit,
Speaker 3: making the orbit elliptical or eccentric.
Speaker 2: The eccentricity is the engine of the tidal heating.
Speaker 3: Exactly because the orbit is slightly elliptical. The gravitational pull
Speaker 3: from the host star changes.
Speaker 2: Constantly on where the planet is in its path.
Speaker 3: When the planet is at its closest point to the star,
Speaker 3: the periastron, the gravitational tug is immense. It physically stretches
Speaker 3: the planet, elongating it along the equator like squeezing a
Speaker 3: rubber ball perfect analogy. Then, as the planet swings further
Speaker 3: away to the distant edge of its elliptical orbit the apostron,
Speaker 3: The star's gravitational grip relaxes slightly.
Speaker 2: And the planet snaps back toward a more perfectly spherical shape.
Speaker 3: Squeeze, release, squeeze, release, every single orbit.
Speaker 2: And these orbits are incredibly fast. We are talking about
Speaker 2: a year that lasts just a few earth days.
Speaker 3: The planet is being relentlessly rhythmically needed like a ball
Speaker 3: of dense dough.
Speaker 1: Wow.
Speaker 3: And this continuous deformation affects the entire thousands of kilometers
Speaker 3: deep mantle of glowing molasses. The internal layers of partially
Speaker 3: molten rock are constantly sliding against each other, grinding, stretching
Speaker 3: and compressing.
Speaker 2: And all of that kinetic energy, all of that internal friction,
Speaker 2: it's converted directly into thermal energy.
Speaker 3: Exactly. The gravitational dance of the neighboring planets is acting
Speaker 3: as a massive planetary scale friction heater. It is injecting
Speaker 3: colossal amounts of energy directly into the mantle.
Speaker 2: This is the mechanism that keeps the pot boiling.
Speaker 3: It is the tidal heating generates the energy. The primordial
Speaker 3: heat provides the baseline temperature. The sulfur greenhouse effect insulates
Speaker 3: the system.
Speaker 2: This perfectly balanced trifecta maintains the magma ocean, which allows
Speaker 2: the continuous out gasing which replenishes the rotten egg atmosphere
Speaker 2: against the relentless stripping of the stellar wind.
Speaker 3: It is a clockwork masterpiece of planetary physics.
Speaker 2: A machine built out of gravity, heat, and chemistry. It
Speaker 2: really is beautiful and understanding. This machine is exactly what
Speaker 2: allowed the researchers in the Nature Astronomy paper to drop
Speaker 2: a bomb on the concept of the radius valid oh totally,
Speaker 2: because we talked earlier about the missing planets problem, the
Speaker 2: assumption that planets either keep their gas and stay big
Speaker 2: or lose their gas, shrink and become bare rocks.
Speaker 3: The binary framework path one and path two right.
Speaker 2: But L ninety eight fifty ninety proves the existence of
Speaker 2: an entirely new evolutionary roadmap. It proves that the universe
Speaker 2: is not limited to subtraction.
Speaker 3: It introduces path three.
Speaker 2: The internalized atmosphere.
Speaker 3: Exactly what the data from L ninety eight to fifty
Speaker 3: ninety demonstrates is that a planet does not need to
Speaker 3: hold onto a fragile primordial envelope of hydrogen to maintain
Speaker 3: a bloated radius and a load density.
Speaker 2: It can literally store its atmosphere inside its own body.
Speaker 3: It absorbs the volatile inventory during formation, sequesters it in
Speaker 3: a deep magma ocean fueled by tidal heating, and then
Speaker 3: slowly continuously bleeds it out over billions of.
Speaker 2: Years, the planet creates its own secondary atmosphere from the
Speaker 2: inside out.
Speaker 3: And this completely changes how we interpret the demographic map
Speaker 3: of the galaxy.
Speaker 2: Because when we look at that massive gap in the
Speaker 2: Radius valley, now we can no longer assume that every
Speaker 2: planet sitting near that forbidden zone is just a dead
Speaker 2: rock that lost its hydrogen.
Speaker 3: We have to consider internal plumbing. A planet sitting on
Speaker 3: the edge of the Radius valley might not be a
Speaker 3: bare core. It might be a highly active, actively outgassing
Speaker 3: magma world wrapped in a dense shroud of heavy metallic volatiles.
Speaker 2: It is puffing itself up with sulfur.
Speaker 3: The size of the planet is being dictated by its
Speaker 3: internal geodynamics just as much as by the external radiation
Speaker 3: of its star.
Speaker 2: We have to stop judging planets by their covers. We
Speaker 2: can't just measure the mass, measure the radius, calculate the
Speaker 2: density and put it in a box.
Speaker 3: No, we really can't. We have to understand the specific
Speaker 3: orbital mechanics that drive its internal heat budget. The complexity
Speaker 3: of planetary evolution just gained an entirely new dimension.
Speaker 2: And the implications of this extend far beyond just solving
Speaker 2: a quark in a demographic graph, right, because the statistical
Speaker 2: reality of path three evolution is actually staggering. Oh it is,
Speaker 2: let's one the numbers on that because L ninety eight
Speaker 2: fifty ninety is just one planet, but it orbits an
Speaker 2: M dwarf a red dwarf star, and.
Speaker 3: M dwarfs are the undisputed rulers of the Milky Way.
Speaker 3: They account for roughly seventy to seventy five percent of
Speaker 3: all stars in our.
Speaker 2: Galaxy and twenty five percent. Our Sun is a G
Speaker 2: type main sequence star, which makes it a minority. The
Speaker 2: galaxy is fundamentally a red dwarf galaxy.
Speaker 3: It is, And what do we know about the planetary
Speaker 3: systems that form around red dwarfs?
Speaker 2: Thanks to missions like Kepler and tests, we know that
Speaker 2: compact multiplanet systems are incredibly common around M dwarfs.
Speaker 3: Right, Systems like Trappist one or L ninety eight fifty nine,
Speaker 3: where you have three four or seven rocky planets huddled
Speaker 3: in tight fast orbits close to the host star.
Speaker 2: So we have a galaxy dominated by red dwarfs, and
Speaker 2: those red dwarfs are frequently surrounded by tight clusters of
Speaker 2: rocky super earths.
Speaker 3: Which means the specific conditions that created L ninety eight
Speaker 3: to fifty ninety are not rare. They are ubiquitous.
Speaker 2: The intense high energy radiation from the young star to
Speaker 2: strip the primordial hydrogen ubiquitous. The close proximity to neighboring
Speaker 2: planets to generate intense tidal heating ubiquitous. The initial accretion
Speaker 2: of volatile.
Speaker 3: Rich material also ubiquitous.
Speaker 2: The perfect storm isn't a freak accident, it is a
Speaker 2: standard weather pattern in the.
Speaker 3: Milky Way exactly, which means Path three isn't just a
Speaker 3: quirky alternative lifestyle for a planet. It might be one
Speaker 3: of the most common planetary end states in the entire universe.
Speaker 2: Wait, really one of the most common.
Speaker 3: It is highly probable that the galaxy is teeming with
Speaker 3: these worlds, sulfur rich, permanently molten hellscapes wrapped in toxic,
Speaker 3: hazy atmospheres.
Speaker 2: So we may be looking at a dominant class of
Speaker 2: exoplanets that we simply couldn't identify until the James Webs
Speaker 2: based telescope gave us the capability to read their chemical fingerprints.
Speaker 3: This single observation effectively creates an entirely new category in
Speaker 3: the catalog of.
Speaker 2: Worlds, and it highlights just how wild the universe is
Speaker 2: compared to our local terrestrial bias. I mean, we grew
Speaker 2: up on a planet with a solid crust, liquid water oceans,
Speaker 2: and a nice nitrogen oxygen atmosphere.
Speaker 3: We kind of assume that rocky planets generally follow the
Speaker 3: rules we see in our own Solar.
Speaker 2: System, right like Venus and Mars are just variation on
Speaker 2: a theme. But L ninety eight fifty nine D is
Speaker 2: playing a different sport entirely.
Speaker 3: It forces a severe pivot in observational astronomy. Now that
Speaker 3: we know what the signature of a magma outgassing world
Speaker 3: looks like. You know, the heavy sulfur absorption bands, that
Speaker 3: density anomaly, the compact orbital architecture.
Speaker 2: We know exactly what to look for we do.
Speaker 3: The follow up campaigns for this specific planet are going
Speaker 3: to be intense, but the broader surveys of similar compact
Speaker 3: systems will be revolutionary.
Speaker 2: So what are the immediate next steps? Because JWST isn't
Speaker 2: done with the system right. The Nature Astronomy paper is
Speaker 2: a monumental leap, but it's based on initial transmission spectra.
Speaker 2: There has to be more data to extract from that
Speaker 2: stinky sky.
Speaker 3: Oh. JWST will undoubtedly conduct more transit observations, utilizing different
Speaker 3: instruments and observing across broader wavelength ranges.
Speaker 2: Okay, what will they be looking for?
Speaker 3: The current detection focus is heavily on the sulfur compounds,
Speaker 3: but astronomers will push the limits of the signal to
Speaker 3: noise ratio to search for traces.
Speaker 2: They'll be hunting for water again.
Speaker 3: Precisely because the magma ocean should also be an efficient
Speaker 3: reservoir for hydrogen and oxygen.
Speaker 2: Ah, is there trace water vapor being outgassed alongside the
Speaker 2: hydrogen sulfide yes?
Speaker 3: And if so, is the stellar radiation destroying it instantly
Speaker 3: or is it lingering in the lower atmosphere. The presence
Speaker 3: or absence of water vapor will further refine the models
Speaker 3: of mantle rheology and volatile solubility.
Speaker 2: I also wonder about variability, like if this planet's atmosphere
Speaker 2: is being sustained by a churning, convecting ocean of glowing molasses.
Speaker 2: The outgassing shouldn't be.
Speaker 3: Perfectly uniform, no, it would be.
Speaker 2: It shouldn't be a smooth static release.
Speaker 3: You would definitely expect episodic variations, major convective overturns in
Speaker 3: the mantle, or localized spikes and tidal heating due to
Speaker 3: orbital resonance cycles. Those could trigger massive planet wide eruptive.
Speaker 2: Events supervolcanic outgassing pulses.
Speaker 3: Exactly, if JWST observes the planet transitting multiple times over
Speaker 3: a period of years and the atmospheric composition or the
Speaker 3: transit depth changes, like if the sulfur dioxide signal suddenly spikes,
Speaker 3: it would provide real time observational evidence of active catastrophic
Speaker 3: volcanic churning in the magma ocean.
Speaker 2: We would literally be watching the planet's internal plumbing operate
Speaker 2: in real time.
Speaker 3: We would and won't just be GWST doing the heavy
Speaker 3: lifting either.
Speaker 2: Well. Right, ground based scopes.
Speaker 3: Now that the target is painted, ground based observatories with
Speaker 3: massive next generation mirrors like the extremely large telescope currently
Speaker 3: under construction, will be able to join the hunt.
Speaker 2: What can they do that JWST can't.
Speaker 3: They can use ultra high resolution spectroscopy to confirm the
Speaker 3: exact volatile ratios and even track the atmospheric as cape
Speaker 3: rates as the wind blows the sulfur away.
Speaker 2: The synergy between space based infrared observatories and massive ground
Speaker 2: based spectrographs is going to rapidly accelerate our mapping of
Speaker 2: these path three worlds.
Speaker 3: We are transitioning from the era of simply finding planets
Speaker 3: to the era of deeply characterizing their geophysical mechanic.
Speaker 2: It's an incredible timeline to think about. I mean, a
Speaker 2: decade ago, a planet thirty five light years away was
Speaker 2: just a dip in a light.
Speaker 3: Curve, a shadow, a twenty shadow.
Speaker 2: We could guess its size and maybe it's mass, and
Speaker 2: we argued about whether it was a rock or a
Speaker 2: gas ball. And today we are diagnosing the viscosity of
Speaker 2: its molten mantle and smelling its rotten egg atmosphere. We
Speaker 2: are dissecting its internal thermodynamics.
Speaker 3: It's a testament to the sheer, relentless ingenuity of the
Speaker 3: people who build these instruments. It really underscores the power
Speaker 3: of empirical observation to humble our theoretical models. We build
Speaker 3: neat boxes based on what we know path one or
Speaker 3: path two. Then the universe presents us with a world
Speaker 3: that shatters those boxes, forcing us to expand our understanding
Speaker 3: of physics and chemistry to accommodate a much wilder reality.
Speaker 2: It's so true. We started this conversation looking at a
Speaker 2: world that is objectively terrifying, a glowing, toxic, boiling hellscape
Speaker 2: where life as we understand it cannot possibly exists.
Speaker 3: Right. The radiation would fry you, the heat would melt you,
Speaker 3: and the atmosphere would suffocate you. It is the ultimate
Speaker 3: anti Earth.
Speaker 2: But I want to look at this mechanism from a
Speaker 2: slightly different angle before we wrap up. Okay, let's take
Speaker 2: a step back from the extreme nightmare of L ninety
Speaker 2: eight fifty nine D and look purely at the planetary
Speaker 2: engine we just spent the last hour unpacking. We have
Speaker 2: an engine driven by tidal and primordial heat, maintaining a
Speaker 2: deep magma ocean that acts as an incredibly stable, billion
Speaker 2: year storage tank for crucial chemical ingredients. We have an
Speaker 2: engine that slowly, reliably degases those volatiles, building and replenishing
Speaker 2: a complex secondary atmosphere from the inside out over geological eons.
Speaker 3: Okay, I see where you're going with this.
Speaker 2: Now take that exact same internal machinery, like exact same
Speaker 2: magma de gassing engine, but mentally move the planet further
Speaker 2: away from the host star.
Speaker 3: Moved out of the blood towards zone.
Speaker 2: Exactly place it safely in the habitable zone where the
Speaker 2: surface temperature is actually cool enough for liquid water to exist,
Speaker 2: but the internal tidal friction keeps the mantle active and convecting.
Speaker 2: Oh wow, could this exact mechanism, this slow billion year
Speaker 2: exhalation of trapped volatiles from a deep internal reservoir, Could
Speaker 2: that be the very engine that jump starts prebiotic chemistry?
Speaker 3: I mean, yes, we know that early Earth had a
Speaker 3: magma ocean phase.
Speaker 2: We know that outgassing from our own mantle built our
Speaker 2: secondary atmosphere and provided the raw chemical building blocks for
Speaker 2: the primordial soup. So by analyzing the extreme lethal overdrive
Speaker 2: version of this planetary engine on L ninety eight fifty nine, dy,
Speaker 2: are we actually reverse engineering the very machinery that creates
Speaker 2: the conditions for life on truly habitable worlds?
Speaker 3: Are we looking at the monstrous, high speed prototype of
Speaker 3: the system that breathes life into our own planet.
Speaker 2: Exactly. It is a profound possibility to consider. We study
Speaker 2: the extremes to understand the middle, and the deeper we
Speaker 2: peer into the chemistry of these hostile worlds, the closer
Speaker 2: we get to understanding the delicate, more miraculous balance required
Speaker 2: to build a world like ours.
Speaker 3: That is. That's a beautiful way to think about it.
Speaker 3: It really is.
Speaker 2: It is something to think about the next time you
Speaker 2: look up at the night sky, past the glare of
Speaker 2: the city lights into the vast, populated darkness of the
Speaker 2: Milky Way. Absolutely, thank you so much for joining us
Speaker 2: on this exploration of the cosmos. The search for diversity
Speaker 2: in the universe continues, and discoveries like this make it
Speaker 2: brilliantly clear that we have only begun to scratch the
Speaker 2: surface of what is out there. Until next time, teachers,
Speaker 2: the
Speaker 3: Gay Chara