How One Small Exoplanet Could Reveal the Fate of Alien Worlds

<v Speaker 1>Welcome to Bedtime Astronomy. Explore the wonders of the cosmos
<v Speaker 1>with our soothing Bedtime Astronomy podcast. Each episode offers a
<v Speaker 1>gentle journey through the stars, planets, and beyond, perfect for
<v Speaker 1>unwinding after a long day. Let's travel through the mysteries
<v Speaker 1>of the universe as you drift off into a peaceful
<v Speaker 1>slumber under the night sky.
<v Speaker 2>What if I told you the best way to figure
<v Speaker 2>out how life survives in the universe is well to
<v Speaker 2>watch a star brutally murder a planet.
<v Speaker 3>Right. It sounds totally counterintuitive, It really.
<v Speaker 2>Does, because you know, when you step outside on a
<v Speaker 2>clear night, maybe you're out away from the city lights,
<v Speaker 2>out in the woods or whatever. You look up and
<v Speaker 2>there's this overwhelming sense of peace.
<v Speaker 3>Oh absolutely, it looks perfectly still.
<v Speaker 2>Exactly a silent, unchanging tapestry. But that tranquility is just
<v Speaker 2>a massive optical illusion, isn't it.
<v Speaker 3>It's the ultimate illusion. We look up and see a
<v Speaker 3>serene painting, but we are actually looking at a continuous, raging,
<v Speaker 3>cosmic crucible. A crucible I like that, Yeah, I mean
<v Speaker 3>every single one of those pin pricks of light is
<v Speaker 3>a massive nuclear furnace. Yeah, And the planet's orbiting them.
<v Speaker 3>They're just caught in the crossfire.
<v Speaker 2>Like innocent bystanders, and the reality of what is actually
<v Speaker 2>happening up there, especially if you are a planet trying
<v Speaker 2>to survive near one of those twinkling lights, is a chaotic, violent,
<v Speaker 2>billion year battle.
<v Speaker 3>It really is. It's a battle against unimaginable stellar radiation.
<v Speaker 2>So today we are looking at a cosmic crime scene.
<v Speaker 3>We are because for a long time, just knowing a
<v Speaker 3>planet existed out there in that chaos, that was enough.
<v Speaker 2>Right, just getting a dot on a graph exactly.
<v Speaker 3>But knowing a planet exists is just the first baby step.
<v Speaker 3>It's the equivalent of knowing a house is on a map.
<v Speaker 2>But you don't know if the house has a roof.
<v Speaker 3>Right understanding if that planet has an atmsosphere, if it
<v Speaker 3>has a sky, if it can actually protect itself from
<v Speaker 3>its own sun. That is the absolute holy grail of
<v Speaker 3>modern astronomy right now.
<v Speaker 2>Okay, let's unpack this, because we are moving far past
<v Speaker 2>that romantic idea of stargazing, way past it. We are
<v Speaker 2>diving straight into the incredibly harsh, brutal physics of exoplanet atmospheres.
<v Speaker 2>Our mission right now is figuring out how these worlds
<v Speaker 2>actually survive their host stars.
<v Speaker 3>And to do that we have to look at a
<v Speaker 3>massive milestone. Humanity is just crossed.
<v Speaker 2>Right, the numbers. We have officially confirmed the existence of
<v Speaker 2>over six thousand exoplanet.
<v Speaker 3>Six thousand individual worlds beyond our Solar system. It is
<v Speaker 3>a staggering number.
<v Speaker 2>It's wild to think about.
<v Speaker 3>If you rewind the clock to the early nineteen nineties,
<v Speaker 3>that number was zero, literally zero zero. I mean, we
<v Speaker 3>had theories, right, we had mathematical models suggesting planet formation
<v Speaker 3>should be common, but we had absolutely zero confirmed planets
<v Speaker 3>orbiting main sequence stars outside our Solar system.
<v Speaker 2>And then nineteen ninety five happened.
<v Speaker 3>Yes, the discovery of fifty one PAGACYB in nine ninety
<v Speaker 3>five blew the doors open. And now, thanks to missions
<v Speaker 3>like Kepler and Tess, we have a true galactic census.
<v Speaker 2>But this census isn't just a random assortment of worlds,
<v Speaker 2>right Like, A massive, undeniable trend has emerged from the data.
<v Speaker 3>Oh, a huge trend, and it completely reshapes how we
<v Speaker 3>view the planetary real estate market.
<v Speaker 2>And that trend is all about M dwarfs commonly known
<v Speaker 2>as red dwarfs.
<v Speaker 3>YEP. The red dwarfs.
<v Speaker 2>If you look at the six thousand planets we've found,
<v Speaker 2>M dwarfs are, by landslide, the most prolific hosts for terrestrial,
<v Speaker 2>rocky exoplanets.
<v Speaker 3>So they absolutely dominate the galaxy.
<v Speaker 2>They really do. So explain what an M dwarf actually is,
<v Speaker 2>just so we have a baseline.
<v Speaker 3>Sure, so, endwarfs are much smaller and much cooler than
<v Speaker 3>our Sun. To give you a sense of scale, our
<v Speaker 3>Sun is what we call a G type main sequence star.
<v Speaker 2>Okay, so a G type.
<v Speaker 3>Right, it's relatively massive and luminous. M dwarfs on the
<v Speaker 3>other hand, well, they can be as small as about
<v Speaker 3>eight percent the mass of our Sun.
<v Speaker 2>Wow, just eight percent. That's tiny.
<v Speaker 3>It's incredibly tiny. Any smaller than that and they wouldn't
<v Speaker 3>have an of gravitational pressure in their cores to fuse hydrogen.
<v Speaker 2>And then there'd just be a failed star exactly.
<v Speaker 3>They'd be brown dwarfs. But because they are so small
<v Speaker 3>and burn their fuel so slowly, they live for trillions of.
<v Speaker 2>Years trillions with a tea with a T.
<v Speaker 3>And they make up roughly seventy to seventy five percent
<v Speaker 3>of all the stars in the Milky Way.
<v Speaker 2>Okay, so if three quarters of the stars in the
<v Speaker 2>galaxy are red dwarfs, mathematically it makes perfect sense that
<v Speaker 2>we'd find the majority of our planets around them.
<v Speaker 3>It does make sense.
<v Speaker 2>Well, wait, I want to push back on this idea
<v Speaker 2>of an M dwarf planetary monopoly for a second. Is
<v Speaker 2>this an actual physical reality of the universe or is
<v Speaker 2>this like an observational bias.
<v Speaker 3>That is a very good question.
<v Speaker 2>Are we just looking under the street lamp because the
<v Speaker 2>light is better there By that, I mean, do M
<v Speaker 2>dwarfs actually form more rocky planets? Or is our telescope
<v Speaker 2>technology just heavily biased toward finding planets around tiny stars.
<v Speaker 3>What's fascinating here is that it is a combination of both.
<v Speaker 3>But the observational bias is incredibly strong due to the
<v Speaker 3>mechanics of how we hunt for planets.
<v Speaker 2>The transit method exactly.
<v Speaker 3>The primary method we use is called the transit method.
<v Speaker 3>We stare at a star and wait for a planet
<v Speaker 3>to cross in front of it, blocking a tiny fraction.
<v Speaker 2>Of its legs, just a tiny shadow.
<v Speaker 3>Right. The amount of light blocked is directly proportional to
<v Speaker 3>the ratio of the planet's area to the stars area.
<v Speaker 2>Okay, so it's a simple geometry problem. If you have
<v Speaker 2>a giant lighthouse and a moth flies in front of it,
<v Speaker 2>the overall light output barely changes.
<v Speaker 3>You'd never notice the shadow, right.
<v Speaker 2>But if you have a tiny, little pocket flashlight and
<v Speaker 2>that same moth flies in front of the lens, it
<v Speaker 2>blocks out a massive percentage of the beam. The dip
<v Speaker 2>in light is obvious.
<v Speaker 3>That's a perfect analogy. If Earth were to transit our Sun,
<v Speaker 3>it would block about one hundred to one percent of
<v Speaker 3>the Sun's light.
<v Speaker 2>That's practically nothing.
<v Speaker 3>It is an incredibly faint signal to detect from light
<v Speaker 3>years away. But if an Earth sized planet transits an
<v Speaker 3>em dwarf that is, say, only a fifth the size
<v Speaker 3>of our Sun, the transit depth, the amount of light blocked,
<v Speaker 3>is twenty five times deeper.
<v Speaker 2>Twenty five times deeper. So the signal is dramatically stronger dramatically,
<v Speaker 2>And it's not just the depth of the shadow, it's
<v Speaker 2>the frequency. Right. Because adwarfs are so cool and dim,
<v Speaker 2>they're habitable zones the orbital band where the temperature is
<v Speaker 2>just right for liquid water to exist. Those zones are
<v Speaker 2>pulled incredibly close to the star.
<v Speaker 3>Precisely if you want to orbit an en dwarf and
<v Speaker 3>stay warm, you have to huddle right up next.
<v Speaker 2>To the fire, like standing right next to a really
<v Speaker 2>weak campfire exactly.
<v Speaker 3>An earth like planet around a sun like star takes
<v Speaker 3>three hundred and sixty five days to complete one orbit.
<v Speaker 3>That means, if we're watching with a telescope, we have
<v Speaker 3>to wait an entire year between transits to confirm the
<v Speaker 3>planet's existence.
<v Speaker 2>Which is agonizingly slow for data collection.
<v Speaker 3>It really is. Yeah, but a rocky planet in the
<v Speaker 3>habitable zone of an M dwarf, it might complete its
<v Speaker 3>orbit in ten days or even less.
<v Speaker 2>Oh wow, so you get a transit every week and
<v Speaker 2>a half.
<v Speaker 3>Yeah, we can observe dozens of transits in a single
<v Speaker 3>observing season, allowing us to stack the data and drastically
<v Speaker 3>increase our signal to noise ratio.
<v Speaker 2>So our instruments are literally perfectly tuned by the laws
<v Speaker 2>of geometry and orbital mechanics to find these specific worlds
<v Speaker 2>they are, which explains why systems like Trappist One completely
<v Speaker 2>shattered the news a few years ago. Trappist one is
<v Speaker 2>like the ultimate poster child for this M dwarf bias. Absolutely,
<v Speaker 2>it's an ultra cool red dwarf barely larger than the
<v Speaker 2>planet Jupiter, located about forty light years away and packed
<v Speaker 2>tightly around in our seven rocky, roughly Earth sized.
<v Speaker 3>Planets, all crammed into this tiny space.
<v Speaker 2>Yeah, and out of those seven, three or four are
<v Speaker 2>sitting right smack in the middle of the habitable zone.
<v Speaker 3>Trappist one was a monumental discovery. It gave us a
<v Speaker 3>miniature solar system that we could study in unprecedented detail
<v Speaker 3>because the star is so small and dim and the
<v Speaker 3>planets are relatively large compared to it.
<v Speaker 2>The flashlight in the moth again, right.
<v Speaker 3>It presented the perfect mathematical conditions for transmissions sectroscopy.
<v Speaker 2>Let's define that, because that is the mechanism we use
<v Speaker 2>to actually figure out if these planets have skies.
<v Speaker 3>Yes, let's break that down.
<v Speaker 2>Because when a planet transits its star, we aren't just
<v Speaker 2>looking at the solid disk of the rock blocking the light. Right.
<v Speaker 2>If the planet has an atmosphere, that atmosphere forms a
<v Speaker 2>tiny translucent ring around the silhouette of the planet like
<v Speaker 2>a halo. Like a halo exactly, and as the starlight
<v Speaker 2>filters through that ring of gas on its way to
<v Speaker 2>our telescopes. The molecules in the atmosphere absorb very specific
<v Speaker 2>wavelengths of light.
<v Speaker 3>It's essentially taking a chemical fingerprint a.
<v Speaker 2>Fingerprint, So how does that actually look in the data?
<v Speaker 3>Well, different molecules, water, carbon dioxide, methane, they all absorb
<v Speaker 3>light at specific frequencies. So by looking at the spectrum
<v Speaker 3>of the starlight during the transit and then subtracting the
<v Speaker 3>section of the star when the planet.
<v Speaker 2>Isn't transitting, you isolate the difference.
<v Speaker 3>Right, you isolate the light that passed through the atmosphere.
<v Speaker 3>The missing wavelenks tell us six what chemicals are floating
<v Speaker 3>in the planet's sky.
<v Speaker 2>Which brings us to the James Web Space Telescope. Because
<v Speaker 2>the JWST was built in large part to do exactly.
<v Speaker 3>This, it's a perfect tool for the job.
<v Speaker 2>It is equipped with incredibly sensitive infrared spectrometers. It was
<v Speaker 2>supposed to point at Trappist one, analyze that filtered starlight,
<v Speaker 2>and tell us what the atmospheres of these seven rocky
<v Speaker 2>worlds were made of, but the results so far have
<v Speaker 2>been a massive reality check.
<v Speaker 3>Reality check is the perfect term. The astronomical community had
<v Speaker 3>very high hopes for finding thick rich atmospheres, perhaps even
<v Speaker 3>secondary atmospheres dominated by carbon dioxide or nitrogen.
<v Speaker 2>Right, we're hoping for basically alien earths.
<v Speaker 3>We were. But the JWST's Mid Infrared Instrument, or Air
<v Speaker 3>Air Eye for short, has looked closely at the innermost
<v Speaker 3>planets of the Trappist one system, specifically Trappist one B
<v Speaker 3>and C.
<v Speaker 2>And what did it find.
<v Speaker 3>Well, it didn't just find a thin atmosphere. It found
<v Speaker 3>absolutely zero evidence of any atmosphere at all.
<v Speaker 2>Fair Rock just totally bare bear rep They are just
<v Speaker 2>naked irradiated stones orbiting in the dark.
<v Speaker 3>Exactly and am I didn't just use transmission spectroscopy either,
<v Speaker 3>It used a technique called thermal phase curve analysis.
<v Speaker 2>Thermal phase curve break that down force.
<v Speaker 3>So, because these planets are so close to their star,
<v Speaker 3>they are tightly locked. This means one side of the
<v Speaker 3>planet constantly faces the star, experiencing eternal day, while the
<v Speaker 3>other side faces deep space in eternal night.
<v Speaker 2>Oh, just like our moon is tidally locked to Earth,
<v Speaker 2>we only ever see one side of.
<v Speaker 3>It, exactly the same mechanism. Now, if a planet has
<v Speaker 3>an atmosphere, that atmosphere acts like a conveyor built for.
<v Speaker 2>Heat like a global air conditioning system.
<v Speaker 3>Right, the intense heat from the day side is carried
<v Speaker 3>by atmospheric winds over to the night side, distributing the
<v Speaker 3>temperature more evenly across the globe.
<v Speaker 2>So the night side isn't freezing cold and the day
<v Speaker 2>side isn't boiling hot.
<v Speaker 3>In theory, yes, but when the JWST measured the infrared
<v Speaker 3>emission the actual heat glowing off trap as one B,
<v Speaker 3>it found that the day side was scorching high, perfectly
<v Speaker 3>matching the theoretical temperature of a bare rock, with absolutely
<v Speaker 3>no mechanism to redistribute the heat. Wow, the heat wasn't moving,
<v Speaker 3>There were no winds, There was no sky.
<v Speaker 2>Which forces us to confront the brutal reality of the
<v Speaker 2>m dwarf planetary system. We have these six thousand planets,
<v Speaker 2>mostly around bread dwarfs. But if they are all just dead,
<v Speaker 2>airless rocks, what does that mean for the search for life?
<v Speaker 2>Why is it so ridiculously hard for a rocky planet
<v Speaker 2>to hold onto its atmosphere in these systems.
<v Speaker 3>To understand this atmospheric peril, we have to look away
<v Speaker 3>from the planet for a moment and look at the
<v Speaker 3>life cycle of the star. Itself, and this requires a
<v Speaker 3>deep dive into stellar physics.
<v Speaker 2>Okay, let's get into the physics.
<v Speaker 3>So M dwarfs do not behave like our Sun. When
<v Speaker 3>our Sun formed from a collapsing cloud of gas and dust,
<v Speaker 3>it contracted, its core, heated up, and it ignited stable
<v Speaker 3>hydrogen fusion. Relatively quickly. It settled into what we call
<v Speaker 3>the main sequence, a stable, calm, long lasting state of equilibrium.
<v Speaker 2>Our Sun had a relatively brief, maybe mildly chaotic childhood
<v Speaker 2>before becoming the reliable, steady light source we rely on exactly.
<v Speaker 3>M dwarfs, however, have an entirely different internal structure. Well.
<v Speaker 3>Our sun has a radiative zone in its interior where
<v Speaker 3>energy moves slowly outward as photons, and that's surrounded by
<v Speaker 3>an outer convective zone where plasma boils and churns, bringing
<v Speaker 3>heat to the surface.
<v Speaker 2>Like a pot of boiling water on a stove.
<v Speaker 3>Sort of, but only the top layer is boiling. The
<v Speaker 3>bottom is just radiating. But M dwarfs, because they are
<v Speaker 3>so small and relatively cool, are fully convective.
<v Speaker 2>Wait fully convected, so the whole thing is boiling.
<v Speaker 3>Yes, the plasma inside an M dwarf is churning and
<v Speaker 3>boiling all the way from the nuclear core right up
<v Speaker 3>to the.
<v Speaker 2>Surface, and that completely changes how the star evolves over time.
<v Speaker 3>It drastically slows down their evolution. Because they are fully convective,
<v Speaker 3>the heat is transported very efficiently to the surface. But
<v Speaker 3>the gravitational contraction, the physical shrinking of the star that
<v Speaker 3>increases core pressure to trigger stable fusion, that takes an
<v Speaker 3>extraordinarily long time.
<v Speaker 2>How long am I talking?
<v Speaker 3>And endwarf can take anywhere from one to two billion
<v Speaker 3>years just to reach the main sequence.
<v Speaker 2>Two billion years. I like to think of this as
<v Speaker 2>a prolonged, wildly violent stellar puberty.
<v Speaker 3>That is an incredibly accurate way to describe it.
<v Speaker 2>They're essentially throwing a billion year long teenage tantrum during
<v Speaker 2>this pre main sequence phase. They aren't the dim, cool,
<v Speaker 2>quiet little flashlights we see later in their lives.
<v Speaker 3>Are They not at all? They are intensely luminous. They
<v Speaker 3>are physically larger, much brighter, and incredibly magnetically active.
<v Speaker 2>And what's driving all that magnetism.
<v Speaker 3>That intense magnetic activity is driven directly by that fully
<v Speaker 3>convective interior. We just talked about the boiling plasma generates massive,
<v Speaker 3>complex magnetic fields through a dynamo process. Okay, and when
<v Speaker 3>those magnetic field lines twist, snap, and reconnect on the
<v Speaker 3>star's surface, they release catastrophic amounts of energy.
<v Speaker 2>Like massive solar flare.
<v Speaker 3>Yes, huge flare and powerful stellar winds, spewing highly charged
<v Speaker 3>particles in extreme ultraviolet and X ray radiation out into
<v Speaker 3>the Solar System.
<v Speaker 2>And remember the geometry we talked about earlier. To be
<v Speaker 2>in the habitable zone of an m dwarf, a rocky
<v Speaker 2>planet has to orbit incredibly close.
<v Speaker 3>To the star, right next to the fire.
<v Speaker 2>Exactly so during this billion year pre main sequence phase,
<v Speaker 2>when the star is at its absolute most violent and luminous,
<v Speaker 2>the planet is sitting right there taking the full, point
<v Speaker 2>blank brunt of this radiation.
<v Speaker 3>The dissipative pressure this puts on an early atmosphere is immense.
<v Speaker 3>When a rocky planet first forms, it naturally accretes a
<v Speaker 3>thick envelope of light gases from the surrounding protoplanetary disc.
<v Speaker 3>It mostly hydrogen and helium.
<v Speaker 2>A primordial atmosphere, right.
<v Speaker 3>A primordial atmosphere, but hydrogen is incredibly light.
<v Speaker 2>So how exactly does the star blow away this hydrogen atmosphere.
<v Speaker 2>Let's get into the actual mechanics here, because it's not
<v Speaker 2>like the star is physically exhaling a gust of wind
<v Speaker 2>that just sweeps the air off the planet, like you know,
<v Speaker 2>blowing leaves off a drive wind.
<v Speaker 3>No, it's not a physical wind like that. It's a
<v Speaker 3>thermal process driven by those extremely high energy photons we mentioned,
<v Speaker 3>the extreme ultraviolet and X ray bands, collectively known as
<v Speaker 3>XUV radiation XUV radiation. Okay, When those high energy XUV
<v Speaker 3>photons strike the uppermost layer of the planet's atmosphere, the thermosphere,
<v Speaker 3>they get absorbed by the gas molecules, and.
<v Speaker 2>That absorption deposits a massive amount of energy into the gas,
<v Speaker 2>which manifests as intense heat right.
<v Speaker 3>Exactly, And heat at the molecular level is just kinetic energy.
<v Speaker 3>It's movement.
<v Speaker 2>Right. The hotter the gas gets, the faster those individual
<v Speaker 2>molecules are sipping around. So if you heat up a
<v Speaker 2>light element like hydrogen to extreme temperatures, those molecules start
<v Speaker 2>moving at incredible speeds.
<v Speaker 3>They do, and if they reach a certain speed, specifically
<v Speaker 3>the escape velocity of the planet's gravitational pull, they overcome
<v Speaker 3>gravity and simply fly off into the vacuum of space.
<v Speaker 2>They just leave yep.
<v Speaker 3>For light molecules like hydrogen, this is known as genes escape.
<v Speaker 3>But what happens around these young, violently flaring m dwarfs
<v Speaker 3>is a much more extreme bulk version of this. It's
<v Speaker 3>called hydrodynamic escape.
<v Speaker 2>Hydrodynamic escape break that down for us.
<v Speaker 3>So the XUV heating from the star is so intense
<v Speaker 3>and the energy input is so rapid that the entire
<v Speaker 3>upper atmosphere expands outward simultaneously, almost like a balloon rapidly inflating.
<v Speaker 2>Okay, I'm picturing that.
<v Speaker 3>As the atmosphere expands further away from the planet's gravitational center,
<v Speaker 3>the planet's grip on the gas weakens, the escape velocity.
<v Speaker 2>Drops because it's further from the core.
<v Speaker 3>Right Eventually, the gas crosses a boundary called the exobase,
<v Speaker 3>where the thermal energy completely overwhelms gravity and the atmosphere
<v Speaker 3>flows away on mass as a continuous planetary wind. It
<v Speaker 3>literally boils off into deep space.
<v Speaker 2>It's like putting a pot of water inside of a
<v Speaker 2>vacuum chamber and turning up the heat. The entire fluid
<v Speaker 2>dynamic structure just violently expands and evaporates.
<v Speaker 3>That's a great visual.
<v Speaker 2>If a planet has a primordial hydrogen atmosphere, it doesn't
<v Speaker 2>stand a chance it gets completely stripped away during that
<v Speaker 2>billion year stellar tantrum.
<v Speaker 3>Which perfectly explains why the inner planets of trappist One
<v Speaker 3>are bare rock. They orbit so close that they were
<v Speaker 3>likely subjected to catastrophic hydrodynamic escape for hundreds of millions
<v Speaker 3>of years.
<v Speaker 2>Here's where it gets really interesting, though, because planets aren't
<v Speaker 2>entirely defenseless. They aren't if they lose that first fluffy
<v Speaker 2>light hydrogen atmosphere, it's not necessarily game over. Some planets
<v Speaker 2>have backup plants. We are finding that heavier, thicker atmospheres
<v Speaker 2>might be the key to survival. What does it actually
<v Speaker 2>take for an atmosphere to withstand a billion year bombardment.
<v Speaker 3>Well, it takes molecular mass an efficient rateate of cooling.
<v Speaker 3>A primordial atmosphere made of hydrogen is highly vulnerable, but
<v Speaker 3>a secondary atmosphere, one dominated by heavier molecules like carbon
<v Speaker 3>dioxide or nitrogen, is physically much harder to strip.
<v Speaker 2>Away because it's heavier.
<v Speaker 3>Exactly, carbon dioxide, for instance, has a molecular weight of
<v Speaker 3>forty four atomic mass units compared to molecular hydrogen's weight
<v Speaker 3>of just two.
<v Speaker 2>That's a huge difference.
<v Speaker 3>It's massive. It requires significantly more kinetic energy to accelerate
<v Speaker 3>a CO two molecule to escape velocity, so.
<v Speaker 2>It's literally just heavier. It's harder for the stellar radiation
<v Speaker 2>to lift it off the surface. But you also mentioned
<v Speaker 2>radiative cooling. How does an atmosphere cool itself down when
<v Speaker 2>it's being blasted by.
<v Speaker 3>X rays is a crucial defense mechanism. Carbon dioxide is
<v Speaker 3>incredibly efficient at radiating heat away in the infrared spectrum.
<v Speaker 2>Okay, how does that work?
<v Speaker 3>When XUV radiation heats up the thermosphere? The CO two
<v Speaker 3>molecules absorb that kinetic energy. But instead of just moving
<v Speaker 3>faster and escaping like hydrogen does, the molecular bonds of
<v Speaker 3>the CO two molecule vibrate.
<v Speaker 2>They vibrate like little springs.
<v Speaker 3>Exactly LIKELO springs, And as they vibrate, they emit that
<v Speaker 3>energy back out into space is infrared photons. By constantly
<v Speaker 3>dumping the star's heat back into space, the CO two
<v Speaker 3>keeps the upper atmosphere relatively cool. Wow, it prevents that
<v Speaker 3>massive thermal expansion that leads to hydro dynamic escape.
<v Speaker 2>So a CO two atmosphere acts like a planetary radiator,
<v Speaker 2>just venting the heat before it can boil the sky away.
<v Speaker 2>That is brilliant, But wait, where does a planet get
<v Speaker 2>a heavy CO two atmosphere if its first hydrogen atmosphere
<v Speaker 2>was destroyed.
<v Speaker 3>That brings us to planetary rebirth through outgassing. The initial
<v Speaker 3>atmospheric stripping happens during the star's volatile pre main sequence phase.
<v Speaker 3>But planets are not static blocks of rock deep inside
<v Speaker 3>their silicon mantles. They contain vast quantities of volatile elements
<v Speaker 3>like what like water, carbon, nitrogen, all trapped in the
<v Speaker 3>rock during the planet's formation.
<v Speaker 2>Oh I see, So long after the endorf has finally
<v Speaker 2>exhausted its tantrum, settled down and entered the stable main sequence,
<v Speaker 2>the rocky planet's interior might still be hot, churning, and
<v Speaker 2>geologically active.
<v Speaker 3>Exactly. The radioactive decay of isotopes in the planet's core,
<v Speaker 3>combined with the immense friction of tidal heating from orbiting
<v Speaker 3>so close to the star, keeps the mantle molten, and
<v Speaker 3>that drives volcanoes intense volcanism. Volcanoes are rupped across the surface,
<v Speaker 3>spewing those trapped gases megatons of water, vapor, carbon dioxide,
<v Speaker 3>and nitrogen from the interior up to the surface.
<v Speaker 2>So the planet essentially burps out a completely new secondary
<v Speaker 2>atmosphere from the inside out, long after the star has
<v Speaker 2>stopped trying to destroy it.
<v Speaker 3>That's exactly what happened.
<v Speaker 2>That is incredible. The star strips the outer layer, but
<v Speaker 2>the planet just rebuilds a fortress from its own core.
<v Speaker 2>And then, of course there is the ultimate planetary shield,
<v Speaker 2>that magnetic field.
<v Speaker 3>Ah, Yes, the magnetic dynamo. If a rocky planet has
<v Speaker 3>a molten, churning liquid iron core and the planet is
<v Speaker 3>rotating fast enough, the Coriolis force organizes the convection currents
<v Speaker 3>of the liquid iron into spiraling columns. Moving conductive fluids
<v Speaker 3>generate magnetic fields. This creates a massive magnetic bubble around
<v Speaker 3>the planet called the magnetosphere.
<v Speaker 2>Just like Earth's magnetic field, which protects us from the
<v Speaker 2>solar wind.
<v Speaker 3>Exactly. The stellar wind from an m dwarf is essentially
<v Speaker 3>a stream of highly arged ionized plasma. When that plasma
<v Speaker 3>hits the planet's magnetic field, the magnetic lines of force
<v Speaker 3>deflect the charged particles steering them around the planet.
<v Speaker 2>So it acts as a physical barrier against the stars
<v Speaker 2>stripping mechanisms.
<v Speaker 3>It does. But and there is a massive caveat here.
<v Speaker 3>Regarding Modworf planets. We mentioned earlier that these plants are
<v Speaker 3>tidally locked because the orbit so close to their stars.
<v Speaker 3>Tidal locking drastically slows down the planet's rotation. A planet
<v Speaker 3>with a ten day orbit rotates exactly once every ten days.
<v Speaker 2>Oh wow. And if it's rotating that slowly, the coriolis
<v Speaker 2>force is incredibly weak.
<v Speaker 3>Precisely, without a strong coriol this forced to organize the
<v Speaker 3>convection currents in the core, the geodynamo might fail. The
<v Speaker 3>planet might not be able to generate this strong enough
<v Speaker 3>global magnetic field to protect its atmosphere.
<v Speaker 2>If we connect this to the bigger picture, you can
<v Speaker 2>start to see why the scientific community currently has no
<v Speaker 2>clear universal conclusions about atmospheric survival around enodworfs.
<v Speaker 3>It's just so complicated.
<v Speaker 2>It is a massive, incredibly complex, multivariable equation. You have
<v Speaker 2>the specific mass of the planet, the exact flaring history
<v Speaker 2>of the star, the initial composition of the primordial envelope, the.
<v Speaker 3>Volatile content of the planet's mantle, driving secondary outgassing.
<v Speaker 2>Right, the efficiency of CO two radiative cooling, the internal
<v Speaker 2>heat driving a magnetic dynamo, and the rotational drag of
<v Speaker 2>tidle locking. It's just all fighting against each other over
<v Speaker 2>billions of years.
<v Speaker 3>The complexity is almost overwhelming. We are trying to model
<v Speaker 3>a chaotic billion year war with dozens of unknown variables.
<v Speaker 3>And this is the fundamental problem facing astrophysics today.
<v Speaker 2>We just don't have enough clear data.
<v Speaker 3>Right if we want to actually solve this puzzle, we
<v Speaker 3>cannot just keep pointing our telescopes at random planets and
<v Speaker 3>hoping a recognizable pattern magically emerges. The data is too noisy,
<v Speaker 3>the variables are too wild.
<v Speaker 2>We realized we don't just need more planets. Getting to
<v Speaker 2>six thousand exoplanets is great, but quantity isn't going to
<v Speaker 2>solve the atmospheric retention problem.
<v Speaker 3>No, it won't.
<v Speaker 2>We need a very specific type of planet. We need
<v Speaker 2>a cosmic measuring stick. We need a benchmark.
<v Speaker 3>Exactly in any rigorous scientific endeavor, when you are dealing
<v Speaker 3>with a chaotic environment filled with interacting variables, you desperately
<v Speaker 3>need a control group or a reference standard.
<v Speaker 2>You get a baseline.
<v Speaker 3>You need a system where certain variables are so well defined,
<v Speaker 3>so meticulously understood and perfectly positioned, that you can finally
<v Speaker 3>start isolating the specific mechanisms of atmospheric escape and retention.
<v Speaker 2>And that incredibly long setup brings us to the star
<v Speaker 2>of the show. Literally, we finally have that benchmark we do.
<v Speaker 2>This is a newly validated exoplanet system. It was discovered
<v Speaker 2>by Francis song Lang, a doctoral researcher at the Center
<v Speaker 2>for Space and Habitability over at the University of burn
<v Speaker 2>in Switzerland, working with an international team of astronomers.
<v Speaker 3>It's forri brilliant piece of work.
<v Speaker 2>I want to introduce you to the ultimate cosmic laboratory.
<v Speaker 2>TOI four six nine B.
<v Speaker 3>TOI four six six c B is a true exceptional find.
<v Speaker 3>But not because it's beautiful or habitable.
<v Speaker 2>No, definitely not habitable.
<v Speaker 3>It is exceptional precisely because of where it sits, what
<v Speaker 3>it is orbiting, in the extreme physics it is currently enduring.
<v Speaker 3>Let's look at the host star first, GOI four six sixteen. Okay,
<v Speaker 3>it is located about ninety one light years away from
<v Speaker 3>us in the constellation of Beotes. In galactic terms, that
<v Speaker 3>makes it a relatively close neighbor. It is classified spectroscopically
<v Speaker 3>as an M four dwarf.
<v Speaker 2>Let's put some hard numbers to that M four classification
<v Speaker 2>so we know exactly what we are dealing with. It
<v Speaker 2>has a radius of roughly zero point one eight eight
<v Speaker 2>nine solar radii, so it is less than a fifth
<v Speaker 2>the size of our Sun. Its mass is about zero
<v Speaker 2>point one eight eight one solar masses, and its effective
<v Speaker 2>surface temperature is hovering right around three thousand, one hundred
<v Speaker 2>and fifty kelvin. Why does the specific M four classification
<v Speaker 2>matter so much?
<v Speaker 3>Because the M four spectral subclass represents a critical transition
<v Speaker 3>point in stellar astrophysics. Remember we discussed how M dwarfs
<v Speaker 3>are fully convective, meaning they're plasmaturns from the core to
<v Speaker 3>the surface.
<v Speaker 2>Yes, the boiling pot of plasma.
<v Speaker 3>Well stars that are slightly more massive, like early type
<v Speaker 3>M dwarfs M one or M two stars, they still
<v Speaker 3>have a tiny remnant of a radiative core, much like
<v Speaker 3>our Sun. Oh Okay, it isn't until you reach the
<v Speaker 3>M three or M four transition boundary, specifically right around
<v Speaker 3>point three to five solar masses, that the star becomes
<v Speaker 3>completely one hundred percent convective.
<v Speaker 2>So this star sits right on that boundary.
<v Speaker 3>Yes, yes, this boundary radically alters the star's magnetic topology
<v Speaker 3>and how it generates those violent stellar flares. By studying
<v Speaker 3>an M four star like TOI four six sixteen, we
<v Speaker 3>are looking right at the archetypal, fully convective red dwarf.
<v Speaker 2>It's the standard model.
<v Speaker 3>It is remarkably ordinary as a star, which is exactly
<v Speaker 3>what you want in a benchmark. You do not want
<v Speaker 3>a weird, anomalous outlier. You want a standard representative of
<v Speaker 3>the majority population.
<v Speaker 2>Okay, so the star is the perfect standard M dwarf,
<v Speaker 2>But the planet orbiting it TOI four six sixteen B
<v Speaker 2>is where the geometry gets critical. Let's look at the
<v Speaker 2>planet's physical properties.
<v Speaker 3>Let's do it.
<v Speaker 2>It has a radius of one point two two earth radii.
<v Speaker 2>That puts it solidly in the terrestrial rocky category. It's
<v Speaker 2>slightly larger than our own planet, which means it has
<v Speaker 2>a solid surface, a mantle, and likely an iron core.
<v Speaker 2>It is not a gas giant, but its orbit.
<v Speaker 3>Is where the physics get extreme. It has an orbital
<v Speaker 3>period of one point five days wow, a single year
<v Speaker 3>on this planet. The time it takes to complete one
<v Speaker 3>full revolution around its star lasts less than thirty eight hours.
<v Speaker 2>Let's just pause and visualize that for a second. If
<v Speaker 2>you were standing on the surface of Toi four six
<v Speaker 2>sixteen B, the sun wouldn't rise and set because of
<v Speaker 2>that insanely tight thirty eight hour orbit. The planet is
<v Speaker 2>violently tidally locked there. Generally, the gravitational gradient across the
<v Speaker 2>planet's body has completely halted its rotation relative to the star.
<v Speaker 3>Yes, the tidal forces at that proximity are immense.
<v Speaker 2>So if you are standing on the day side at
<v Speaker 2>what astronomers call the substellar point, the exact spot where
<v Speaker 2>the star is directly overhead, you are looking up at
<v Speaker 2>a massive, deep red sun that occupies a huge portion
<v Speaker 2>of the sky, and it never ever moves. It just
<v Speaker 2>hangs there eternally baking the surface. And because it is
<v Speaker 2>so close, the equilibrium temperature of the planet is blisteringly
<v Speaker 2>hot around five hundred and twenty.
<v Speaker 3>Five kilvin that is over two hundred and fifty degrees
<v Speaker 3>celsius or nearly five hundred degrees fahrenheit. The day side
<v Speaker 3>is likely a scorched, barren wasteland, possibly with localized pools
<v Speaker 3>of molten silicate depending on the exact heat distribution just
<v Speaker 3>to Hellscape. Absolutely, and that specific set of parameters is
<v Speaker 3>what led the researchers to explicitly designate this system as
<v Speaker 3>a reference system for highly irradiated rocky planets. It exists
<v Speaker 3>in a very specific, perfectly balanced intermediate.
<v Speaker 2>Regime, intermediate between what we have.
<v Speaker 3>Discovered Earth sized planets that orbit larger, hotter early type
<v Speaker 3>M dwarfs, and we have discovered planets that orbit tiny
<v Speaker 3>ultra cool hosts like the Trappis. One system we discussed earlier,
<v Speaker 3>which is an ME eight star GOI forty six sixteen
<v Speaker 3>b sits exactly in the middle of the M dwarfs
<v Speaker 3>back but because of that relentless one point five day orbit,
<v Speaker 3>it resides in an extreme irradiation environment. It bridges the
<v Speaker 3>gap in our empirical data.
<v Speaker 2>I love how this is described to me. This planet
<v Speaker 2>is essentially the ultimate crash test dummy for astrophysics.
<v Speaker 3>That is a highly accurate analogy.
<v Speaker 2>I mean, think about the logic of a crash test.
<v Speaker 2>If you want to know how well a car's chassis
<v Speaker 2>handles a violent impact, you don't drive it at five
<v Speaker 2>miles an hour around a.
<v Speaker 3>Track no, you don't learn anything from that exactly.
<v Speaker 2>You load it up with high speed cameras and sensors,
<v Speaker 2>you drive it full speed into a concrete wall, and
<v Speaker 2>you study the absolute catastrophic destruction of the vehicle. You
<v Speaker 2>study how the metal crumbles, how the kinetic energy transfers.
<v Speaker 3>And that is exactly what TOI four six sixteen B.
<v Speaker 2>Is we fully expect that because of that insane thirty
<v Speaker 2>eight hour orbit, because it has been blasted by extreme
<v Speaker 2>XUV radiation for billions of years, the bulk of its
<v Speaker 2>atmosphere is probably already completely gone.
<v Speaker 3>It has been absolutely roast.
<v Speaker 2>But that expected destruction is the very thing that makes
<v Speaker 2>it so incredibly valuable to us.
<v Speaker 3>The fact that its atmosphere is in such absolute peril,
<v Speaker 3>or perhaps has already been entirely destroyed, makes it an
<v Speaker 3>exquisitely informative test case for setting boundary conditions. When we
<v Speaker 3>observe this planet with advanced telescopes, we can definitively test
<v Speaker 3>our complex models of atmospheric escape. If we point the
<v Speaker 3>JWST at it and find absolutely nothing a flag transmission
<v Speaker 3>spectrum indicating bare rocket, it confirms our models of hydrodynamic
<v Speaker 3>escape for this mass and irradiation level.
<v Speaker 2>And what if we find something, What if there's a
<v Speaker 2>trace of an atmosphere.
<v Speaker 3>Left that would be even more profound. It would allow
<v Speaker 3>us to measure volatile retention. If we detect a heavy
<v Speaker 3>CO two atmosphere or traces of sulfur dioxide indicating active volcanism,
<v Speaker 3>it tells us exactly what mechanisms are required to fight
<v Speaker 3>off the stellar wind at that specific proximity.
<v Speaker 2>That makes total sense.
<v Speaker 3>It tells us that secondary outgassing can outpace stellar stripping
<v Speaker 3>even at a one point five to five day orbit.
<v Speaker 3>It's essentially forensic science on a planetary scale.
<v Speaker 2>We are examining a cosmic crime scene where the star
<v Speaker 2>attempted to murder the atmosphere, and we are looking for
<v Speaker 2>the exact mechanism of death or the exact mechanism of survival.
<v Speaker 2>Was it boiled off, was it blown away? Did the
<v Speaker 2>planet try to outgas a second atmosphere that also got destroyed.
<v Speaker 3>By perfectly understanding how TOI four sixty sixty sixteen B
<v Speaker 3>reacts to its specific level of extreme radiation, we learn.
<v Speaker 2>The rules of the game, and then we can take
<v Speaker 2>those rules and apply them to the thousands of other
<v Speaker 2>highly irradiated terrestrial planets we've discovered exactly.
<v Speaker 3>But there is a massive catch to all of this.
<v Speaker 2>Oh there's always a catch.
<v Speaker 3>A planet, no matter how perfectly positioned as a benchmark
<v Speaker 3>crash test dummy, is only as useful as the data
<v Speaker 3>we have on its host star. You cannot understand the
<v Speaker 3>impact of the crash if you do not deeply, perfectly
<v Speaker 3>understand the concrete wall the car just hit right.
<v Speaker 2>If you don't know the density of the wall, the
<v Speaker 2>crash data is useless. So why is TOI four sixty
<v Speaker 2>sixteen B such a spectacularly better tar for the James
<v Speaker 2>Web Space Telescope than the thousands of other rocky exoplanets
<v Speaker 2>out there? We have six thousand planets. Why is this
<v Speaker 2>specific star the absolute key to unlocking the mystery?
<v Speaker 3>It comes down to a fundamental limitation and how we
<v Speaker 3>study exoplanet atmospheres using transmission spectroscopy. The JDWUST is an
<v Speaker 3>incredibly powerful instrument. Obviously it's the pinnacle of human engineering.
<v Speaker 3>But when it looks at a transitting planet, it is
<v Speaker 3>not taking a high definition photograph.
<v Speaker 2>It's not taking a picture like we think of a picture.
<v Speaker 3>No, it is capturing a single pixel of light. It's
<v Speaker 3>the combined blended light of the star and the planet's
<v Speaker 3>tiny atmospheric silhouette.
<v Speaker 2>It's all mashed together into one spectral reading exactly.
<v Speaker 3>And the problem is m dwarfs are not uniform static
<v Speaker 3>light bulbs. They are highly active, variable, chaotic surfaces. They
<v Speaker 3>are covered in massive stellar spots, cool dark patches on
<v Speaker 3>the star's photosphere caused by concentrated magnetic fields suppressing convection.
<v Speaker 2>And I also have bright spots too, right.
<v Speaker 3>Faculae, which are exceptionally bright hot magnetic regions.
<v Speaker 2>So they are covered in star spots incredibly similar to
<v Speaker 2>sunspots on our own sun, but scaled up massively relative
<v Speaker 2>to the size of the tiny star. A single star
<v Speaker 2>spot on an en dwarf can cover a significant percentage
<v Speaker 2>of its entire visible surface.
<v Speaker 3>And this creates a catastrophic problem for spectroscopy known as
<v Speaker 3>the transit light source effect.
<v Speaker 2>The transit light source effect what is that when a
<v Speaker 2>planet transits across a star, it is covered in spots.
<v Speaker 3>The varying brightness of the stellar surface creates massive noise
<v Speaker 3>in the data. But it's worse than just random noise
<v Speaker 3>a stellar spot because it is cooler than the rest
<v Speaker 3>of the star has a different chemical spectrum. Oh, it
<v Speaker 3>might contain molecules like water vapor or titanium oxide within
<v Speaker 3>the star's own atmosphere.
<v Speaker 2>Oh wow. So if the planet transits across a bright
<v Speaker 2>part of the star, but there's a dark spot elsewhere
<v Speaker 2>on the surface that the planet isn't blocking, the overall
<v Speaker 2>light we receive is suddenly weighted differently.
<v Speaker 3>Yes, the unoccult at star spots make the transited cord
<v Speaker 3>look artificially bright by comparison, and the chemical signature of
<v Speaker 3>the star spot gets imprinted into the trandit data.
<v Speaker 2>That's crazy.
<v Speaker 3>It can literally mimic the chemical signature of a planetary
<v Speaker 3>atmosphere in the telescope spectrograph. It's a cruel optical illusion.
<v Speaker 2>So it's like a fake signal, entirely fake.
<v Speaker 3>Astronomers could look at the data, see a massive spike
<v Speaker 3>in water absorption and publish a paper claiming they found
<v Speaker 3>a water world, when in reality they just saw the
<v Speaker 3>water vapor inside a cold magnetic storm on the star's surface.
<v Speaker 2>So if we lack precise long term measurements of the
<v Speaker 2>host stars behavior, its variability, its specific rotation rate, it's
<v Speaker 2>multi year spot cycles. The data that JWST collects on
<v Speaker 2>the planet's atmosphere becomes.
<v Speaker 3>Completely muddy, completely ambiguous, and scientifically useless. We cannot separate
<v Speaker 3>the stellar noise from the planetary signal.
<v Speaker 2>Man So how do we get around that?
<v Speaker 3>Well, the only mathematical way out of this trap is
<v Speaker 3>to find a star whose noise we already know perfectly.
<v Speaker 3>We need to know exactly how the star's light fluctuates
<v Speaker 3>over a long period of time, mapping its magnetic cycles,
<v Speaker 3>so we can basically subtract the star's personality from the data.
<v Speaker 2>Leaving behind only the pure, uncontaminated atmospheric signature of the
<v Speaker 2>planet exactly.
<v Speaker 3>And this is where the story of TOI forty six
<v Speaker 3>sixteen becomes truly extraordinary. It becomes a literal time machine
<v Speaker 3>of human observation.
<v Speaker 2>This is my absolute favorite part of this entire discovery,
<v Speaker 2>because this isn't just some random star we noticed with
<v Speaker 2>the satellite yesterday. We have archival astronomical data on this
<v Speaker 2>specific m dwarf dating all the way back to nineteen
<v Speaker 2>fifty four.
<v Speaker 3>Which is absolutely profound when you think about the history
<v Speaker 3>of astronomy. We have over seven decades of data tracking
<v Speaker 3>the luminosity and behavior of this specific star.
<v Speaker 2>Let's dig into how that is even possible. In nineteen
<v Speaker 2>fifty four, we didn't have digital cameras, we didn't have
<v Speaker 2>CCD rays. Astronomers were executing the Palomar Observatory Sky Survey
<v Speaker 2>or POSS POSS. They were using massive ground based telescopes
<v Speaker 2>manually guiding them through the night, and meticular capturing the
<v Speaker 2>faint light of distant stars on physical glass photographic plates
<v Speaker 2>coated with chemical emulsions.
<v Speaker 3>It was a painstaking, highly physical process. These glass plates
<v Speaker 3>were carefully developed and stored in massive archival libraries.
<v Speaker 2>But are they really that useful today?
<v Speaker 3>Obviously, the photometric precision of a chemical glass plate from
<v Speaker 3>the nineteen fifties isn't as high resolution as a modern
<v Speaker 3>digital sensor, but what it provides is a massive, unparalleled
<v Speaker 3>historical baseline. By digitizing those old glass plates and comparing
<v Speaker 3>the brightness of TOI four six sixteen in nineteen fifty
<v Speaker 3>four to its brightness today, we can establish the star's
<v Speaker 3>long term variability.
<v Speaker 2>So we can see if it has decades long magnetic cycles,
<v Speaker 2>much like our sun's eleven year solar cycle exactly. So
<v Speaker 2>what does this all mean? I want you to really
<v Speaker 2>think about the gravity of this for a second. In
<v Speaker 2>nineteen fifty four, astronomers were freezing in a dome, carefully
<v Speaker 2>exposing a piece of glass to the night sky. They
<v Speaker 2>were simply cataloging the brightness of a random, faint red star.
<v Speaker 3>Just doing routine work.
<v Speaker 2>Right. They were completely and utterly unaware that seventy two
<v Speaker 2>years later, in twenty twenty six, their meticulous physical note
<v Speaker 2>taking would be the exact mathematical key needed to characterize
<v Speaker 2>an Earth's sized exoplanet.
<v Speaker 3>It's incredible to think about.
<v Speaker 2>They were unknowingly setting the foundational baseline needed to study
<v Speaker 2>the atmosphere of an alien world. They couldn't possibly have
<v Speaker 2>known existed. The transit method hadn't even been theorized yet.
<v Speaker 2>It is just a mind blowing connection across generations of
<v Speaker 2>scientific pursuit.
<v Speaker 3>It beautifully illustrates the cumulative, deeply collaborative nature of astronomy.
<v Speaker 3>No observation, no matter how mundane it seems at the time,
<v Speaker 3>is ever wasted, and that nineteen fifty four baseline is
<v Speaker 3>supported by an incredible, unbroken chain of modern observational campaigns.
<v Speaker 2>Walk us through the modern timeline. How did we get
<v Speaker 2>from glass plates to knowing the planet has a one
<v Speaker 2>point five to five day orbit.
<v Speaker 3>Well, the star was observed extensively by the pan Stars
<v Speaker 3>survey starting in twenty eleven. PANT Stars uses massive digital
<v Speaker 3>cameras to map the sky continuously establishing highly precise modern
<v Speaker 3>photometric baselines.
<v Speaker 2>Okay, so a massive upgrade from glass plates.
<v Speaker 3>Huge upgrade. We knew exactly how the stars light fluctuated
<v Speaker 3>over months and years. Then it was observed by the
<v Speaker 3>test satellite, the Transiting Exoplanet Survey satellite test park its
<v Speaker 3>cameras on this sector of the sky and monitor the
<v Speaker 3>star's brightness every.
<v Speaker 2>Two minutes, every two minutes, that's incredible resolution.
<v Speaker 3>It was tests that finally caught the tiny recurring dips
<v Speaker 3>in light, discovering the one point five to five day
<v Speaker 3>transits of planet Beak.
<v Speaker 2>And we didn't stop there because a transit only tells
<v Speaker 2>you the size of the planet. To know if it
<v Speaker 2>can hold an atmosphere, you need its mass.
<v Speaker 3>Precisely, which is why the system is slated for extremely
<v Speaker 3>precise radial velocity measurements by the S and O and
<v Speaker 3>Artemis facilities in twenty twenty.
<v Speaker 2>Five and beyond radio velocity right right.
<v Speaker 3>Radio velocity measures the microscopic Doppler shift in the star's light,
<v Speaker 3>the blue shift and red shift as the gravity of
<v Speaker 3>the orbiting planet physically tugs the star back and forth.
<v Speaker 3>Measuring that wobble, we can calculate the exact mass and
<v Speaker 3>density of TOOI four six sixteen B.
<v Speaker 2>So we have this absolute treasure trove of multigenerational, multi
<v Speaker 2>instrument data. A massive host of telescopes across decades, with
<v Speaker 2>vastly different capabilities, from glass plates to space based infrared
<v Speaker 2>sensors to ground based Doppler spectrometers, have all focused their
<v Speaker 2>lenses on this one quiet, little M four dwarf.
<v Speaker 3>We know this star inside and out. We know it's
<v Speaker 3>exact mass, it's radius, it's temperature, and crucially it's magnetic personality.
<v Speaker 2>This raises an important question regarding the immediate future of
<v Speaker 2>our atmospheric studies. The researchers in the paper explicitly point
<v Speaker 2>out that it is the specific combination of these factors
<v Speaker 2>that makes this system unparalleled.
<v Speaker 3>It really is unparalleled. It is the.
<v Speaker 2>Precise stellar parameters derived from decades of study, the consistent
<v Speaker 2>multiban transit measurements across different wavelengths of light, and the
<v Speaker 2>host star's relative brightness in our local neighborhood.
<v Speaker 3>Yes, because it's only ninety one light years away, it's
<v Speaker 3>bright enough for the JADAST to get a brilliant high
<v Speaker 3>resolution spectrum exactly.
<v Speaker 2>By perfectly understanding the stellar noise of TOI four six sixteen,
<v Speaker 2>we eliminate the transit light source effect. The JWST can
<v Speaker 2>look at planet B, subtract the star's exact known baseline,
<v Speaker 2>and extract a pristine, mathematically pure, uncontaminated signal of whatever
<v Speaker 2>is or isn't clinging to its rocky surface.
<v Speaker 3>It is the ultimate Rosetta stone for m dwarf planets.
<v Speaker 3>If we can read the history of destruction on TOI
<v Speaker 3>four six sixteen B without the stars like confusing our instruments,
<v Speaker 3>we finally learn the absolute rules of planetary survival.
<v Speaker 2>And what rules are we learning exactly?
<v Speaker 3>We map the exact mechanics of how atmospheres are stripped
<v Speaker 3>away by XUV radiation, which in turn tells us what
<v Speaker 3>an atmosphere needs in terms of mass, composition and magnetic
<v Speaker 3>defense to survive. By establishing this incredibly precise benchmark, we
<v Speaker 3>calibrate our theoretical models and our expectations for every other
<v Speaker 3>rocky planet we will ever study in an mb war's
<v Speaker 3>habitable zone.
<v Speaker 2>Which brings us back to you listening to this right now,
<v Speaker 2>and that overarching quest to understand our place in the galaxy.
<v Speaker 2>We started by looking at the staggering milestone of crossing
<v Speaker 2>the six thousand exoplanet threshold.
<v Speaker 3>Moving from a universe where we thought we were alone
<v Speaker 3>to a galaxy teeming with worlds exactly.
<v Speaker 2>We dug into the physics of why dim fully convective
<v Speaker 2>m dwarfs dominate this planetary real estate and how our
<v Speaker 2>instruments are biased to find them.
<v Speaker 3>We examined the terrible cost of that real estate, the
<v Speaker 3>violent billion year pre main sequence phase of these red dwarfs,
<v Speaker 3>the relentless flaring, the extreme ultraviolet radiation, and the catastrosic
<v Speaker 3>hydrodynamic escape that puts early primordial atmospheres in total peril,
<v Speaker 3>boiling them away into the vacuum.
<v Speaker 2>And out of that chaos we found our anchor. The
<v Speaker 2>discovery of TOI four six sixteen B provides humanity with
<v Speaker 2>the ultimate cosmic benchmark. An Earth sized world trapped in
<v Speaker 2>a scorching thirty eight hour orbit, tidally locked and baking
<v Speaker 2>under a red sun, but backed by an astonishing seventy
<v Speaker 2>two years of um human observation. It is the perfect
<v Speaker 2>laboratory because every single time we find a world like this,
<v Speaker 2>a world that has been battered, heavily irradiated, and potentially
<v Speaker 2>stripped utterly bare by its star, it is actually a
<v Speaker 2>profound gift to science.
<v Speaker 3>It teaches us exactly what is required for a planet
<v Speaker 3>to remain a safe harbor by showing us exactly how
<v Speaker 3>an atmosphere dies. It shows us what an atmosphere needs
<v Speaker 3>to live.
<v Speaker 2>The absence of an atmosphere on a highly irradiated benchmark
<v Speaker 2>planet provides just as much vital empirical data as the
<v Speaker 2>presence of one on a cooler world. It defines the
<v Speaker 2>absolute boundary conditions for habitability in the universe. It tells
<v Speaker 2>us where the line is drawn it does, which leaves
<v Speaker 2>us with a lingering thought. I want you tomul Over
<v Speaker 2>the next time you look up at that seemingly peaceful
<v Speaker 2>night sky, think about TOI forty six sixteen B locked
<v Speaker 2>in its violent orbit. If the James Web Space Telescope
<v Speaker 2>points its golden mirrors at that system next year and
<v Speaker 2>finds that the planet's atmosphere has been completely and utterly annihilated,
<v Speaker 2>leaving absolutely nothing behind but a bearer radiated rock.
<v Speaker 3>It's very possible.
<v Speaker 2>Does that actually make it the most important planet we've
<v Speaker 2>ever found? Because by perfectly completely understanding a dead world,
<v Speaker 2>we finally map the exact razor thin boundary line of
<v Speaker 2>where life sustaining atmospheres can even begin to exist. It's
<v Speaker 2>this incredible paradox that, in astronomy, perfect destruction is the
<v Speaker 2>exact key to understanding creations.
<v Speaker 4>The passat
<v Speaker 2>S