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: So I want you to imagine, just for a second,
Speaker 2: that you are an archaeologist. Okay, I'm with you, but
Speaker 2: you aren't, you know, hacking your way through a dense,
Speaker 2: uncharted jumble somewhere. And you're definitely not sifting through the
Speaker 2: remote sands of Egypt.
Speaker 3: Right, none of the Indiana Jones stuff exactly.
Speaker 2: Instead, you are standing right in the middle of a bustling,
Speaker 2: hyper modern, neonlit metropolis. I mean, cars are just zooming by,
Speaker 2: massive skyscrapers are towering overhead, and there are millions of
Speaker 2: people rushing around in this well, this chaotic symphony of modern.
Speaker 3: Life sounds pretty overwhelming, honestly it is.
Speaker 2: But then right there, sitting completely unnoticed in the middle
Speaker 2: of a twelve lane super highway, you spot something that
Speaker 2: is just flat out impossible.
Speaker 3: An agent artifact.
Speaker 2: Yes, an absolutely pristine, untouched mint condition model T four,
Speaker 2: just you know, idling in the fast lane. Right. It's
Speaker 2: completely out of place among all the electric vehicles and
Speaker 2: the hyper modern infrastructure. It really shouldn't be there at all.
Speaker 2: It belongs to an entirely different era. But there it is,
Speaker 2: just hiding in plain sight. And if you pop the hood,
Speaker 2: the engine block actually holds the very engineering secrets of
Speaker 2: how the first factories were ever built.
Speaker 3: That visual the whole anachronism of it. It maps perfectly
Speaker 3: onto the reality of what we were looking at in
Speaker 3: this deep dive today. Yeah, because we're dealing with an
Speaker 3: object that frankly fundamentally breaks the timeline of its surroundings.
Speaker 2: It really does.
Speaker 3: Yeah, it's a relic from the absolute beginning of history.
Speaker 3: It's preserving a state of the universe that's supposedly vanished
Speaker 3: over thirteen billion years ago.
Speaker 2: Thirteen billion years. It's staggering. We are tracking down the
Speaker 2: ultimate cosmic relic today, the most pristine star ever found
Speaker 2: in the known universe.
Speaker 3: And it has a very catchy name too, right.
Speaker 2: Oh, the catchiest. It has a deeply unglamorous catalog name
Speaker 2: SDSSJ zero seven. One, five, seven three three four. But
Speaker 2: the single faint point of light is that exact model
Speaker 2: t Ford on the Galactic super Highway, hiding and plain
Speaker 2: sight exactly. So today we're going to explore the mechanics
Speaker 2: of what actually makes a star truly pristine. You know,
Speaker 2: we'll get into the massive automated technological ecosystem that was
Speaker 2: required to even locate it.
Speaker 3: It's a story itself, huge.
Speaker 2: Story, and maybe my favorite part the incredible human element,
Speaker 2: the undergraduate students who actually cracked its chemical code while
Speaker 2: on a spring break field trip.
Speaker 3: It's just such a great narrative, it really.
Speaker 2: Is, because when you step outside and look up at
Speaker 2: the night sky, you aren't just seeing lights. You are
Speaker 2: looking at a multi generational family tree of stellar evolution.
Speaker 2: You've got you know, parents, grandparents, highly complex descendants up there,
Speaker 2: and today we are meeting the ultimate ancestor.
Speaker 3: To really grasp the mechanical improbability of STSSG zero seven
Speaker 3: one five, seven, three three four surviving all the way
Speaker 3: to the present day, we kind of have to rewind
Speaker 3: the clock all the way back, right all the way
Speaker 3: back to the era immediately following the Big Bank, Specifically
Speaker 3: this period we call the epoch of recombination.
Speaker 2: Okay, so set the scene for us. What does that
Speaker 2: look like.
Speaker 3: So we're talking about a period roughly three hundred and
Speaker 3: eighty thousand years after the initial expansion. That is when
Speaker 3: the universe finally cooled down enough for the ambient radiation
Speaker 3: to drop below the ionization threshold of hydrogen.
Speaker 2: That's the moment the fog finally lifted.
Speaker 3: Exactly the fog lifted, because before that point the universe
Speaker 3: was essentially this opaque plasma. Protons and electrons were just
Speaker 3: zipping around with so much kinetic energy that they couldn't
Speaker 3: bind together.
Speaker 2: Like a hyperactive mosh pit.
Speaker 3: That's a good way to pickture, and any photon of
Speaker 3: light that tried to travel through that mess would just
Speaker 3: instantly scatter off a free electron. The universe was effectively
Speaker 3: this blinding, superheated soup.
Speaker 2: You couldn't see anything even if you were there, right.
Speaker 3: But as space expanded, the thermal energy of those particles
Speaker 3: began to drop, and once the temperature dipped below about
Speaker 3: three thousand kelvin, something crucial happened.
Speaker 2: They slowed down enough to stick exactly.
Speaker 3: The electrostatic attraction between the protons and electrons. Finally overcame
Speaker 3: all that kinetic energy. They snapped together and they formed
Speaker 3: the very first neutral atoms.
Speaker 2: And those first atoms were incredibly basic.
Speaker 3: Right, extremely basic. They were almost exclusively hydrogen, with you know,
Speaker 3: a smattering of helium and just a negligible trace of lithium.
Speaker 3: And that was it. That was the entire periodic table
Speaker 3: at that moment.
Speaker 2: No carbon, no oxygen, no iron, nothing.
Speaker 3: Just a vast cooling ocean of neutral gas slowly settling
Speaker 3: into what we call the cosmic dark ages.
Speaker 2: Which sounds ominous, but it's really just the stage being set.
Speaker 2: Because out of that pristine, incredibly simple gas, gravity had
Speaker 2: to somehow figure out a way to build the first
Speaker 2: generation of stars what your astronomers call population three.
Speaker 3: Stars, right, population three, And the thermodynamics of that building
Speaker 3: process are incredibly hostile to star formation.
Speaker 2: Why is that.
Speaker 3: Well, for a cloud of gas to collapse into a star,
Speaker 3: gravity basically has to win a tug of war against
Speaker 3: thermal pressure. When you can press gas, it heats up.
Speaker 3: Everybody knows that.
Speaker 2: Right, right, Like pumping up a bicycle tire, the pump
Speaker 2: gets hot exactly.
Speaker 3: So if that gas cloud can't radiate that newly generated
Speaker 3: heat away into space. The thermal pressure pushes back against gravity,
Speaker 3: and the collapse just halts. It stops dead.
Speaker 2: So it needs a way to cool down while it's collapsing.
Speaker 3: Yes, in the modern universe, gas clouds contain heavier elements carbon, oxygen, silicon,
Speaker 3: and these elements are fantastic cool ones.
Speaker 2: How do they cool things down in the vacuum of space.
Speaker 3: Their atomic structures are complex, so they they allow them
Speaker 3: to easily absorb kinetic energy from all the particles colliding
Speaker 3: around them, and then they radiate that energy away as
Speaker 3: infrared light.
Speaker 2: Okay, so they act like thermal exhaust vents for the
Speaker 2: gas cloud. They let it cool down, lose that outward pressure,
Speaker 2: and then gravity can keep crushing it together.
Speaker 3: That is a perfect analogy thermal exhaust vents. But here's
Speaker 3: the problem. Those first population three stars, they didn't have heavy.
Speaker 2: Elements, right because nothing had made them yet. They only
Speaker 2: had hydrogen and helium exactly.
Speaker 3: And molecular hydrogen is an incredibly inefficient coolant. It's terrible
Speaker 3: at it. So the only way gravity could overcome the
Speaker 3: fierce thermal pressure that pristine gas was through sheer overwhelming mass.
Speaker 2: It just had to brute force the collapse.
Speaker 3: Yes, the physics essentially required these first generation stars to
Speaker 3: be absolute behemoths. We are talking hundreds, perhaps even a thousand,
Speaker 3: times the mass of our modern sun. That was the
Speaker 3: only way to force the gas to collapse enough to
Speaker 3: ignite nuclear fusion.
Speaker 2: So the gravitational crush just had to be immense to
Speaker 2: trigger that ignition. And because they were so massive, their
Speaker 2: core temperatures would have been unimaginably high off the.
Speaker 3: Charts, and a star's lifespan is entirely dictated by the
Speaker 3: temperature of its core. A massive star doesn't just burn
Speaker 3: its fuel linearly faster than a small star. It burns
Speaker 3: it exponentially faster.
Speaker 2: It's like a gas guzzling supercar compared to an economy sedan.
Speaker 3: Exactly the extreme pressure in a population the third star
Speaker 3: would have forced its hydrogen fusion process to just run
Speaker 3: at maximum capacity constantly. It had to do that just
Speaker 3: to maintain hydrostatic equilibrium.
Speaker 2: Hydrostatic equilibrium being the balance between gravity crushing it and
Speaker 2: fusion pushing out right.
Speaker 3: So to maintain that balance, they burned incredibly fast. They
Speaker 3: lived incredibly brief, violently energetic lives, and they exhausted their
Speaker 3: fuel in just a few million years.
Speaker 2: Which in the lifespan of the universe is a cosmic
Speaker 2: blink of.
Speaker 3: An eye, not even a blink. And when they ran
Speaker 3: out of fuel, that outward pressure from the fusion just stopped.
Speaker 3: Gravity won the tug of war instantly, and the core.
Speaker 2: Collapsed, resulting in supernova right core.
Speaker 3: Collapse supernovaes or even parents stability supernova, which are so
Speaker 3: violent they completely obliterate the star without leaving even a
Speaker 3: black hole behind. Just total destruction.
Speaker 2: Wow, total obliteration.
Speaker 3: But the really crucial mechanic here for our story is
Speaker 3: what happened in the moments leading up to and during
Speaker 3: those massive explosions.
Speaker 2: The alchemy part of it.
Speaker 3: Yes, the intense pressures and temperatures inside these dying bohemos
Speaker 3: acted as stellar forges through a process called nucleosynthesis. They
Speaker 3: smashed helium atoms together to make carbon okay, and then
Speaker 3: they fused carbon to make oxygen, then neon silicon all
Speaker 3: the way up to the periodic table to iron. And
Speaker 3: then the explosion itself synthesized even heavier elements and blasted
Speaker 3: all this newly forged material out into the pristine cosmic ocean.
Speaker 2: So they essentially seated the universe with the very first
Speaker 2: heavy elements, the first pollution basically, and actually this brings
Speaker 2: up that's that terminology quirk we should probably address because
Speaker 2: it definitely changes how we have to read the data
Speaker 2: later on.
Speaker 3: Yes, the astronomer's definition.
Speaker 2: Of metals, right, because in astrophysics, the periodic table is
Speaker 2: basically divided into three distinct things hydrogen, helium, and everything else,
Speaker 2: and everything else gets grouped into one single word metals.
Speaker 3: Yeah, two in astronomer Literally, anything heavier than helium is a.
Speaker 2: Metal, which is so confusing for the rest of us.
Speaker 3: I know, I know, oxygen is a metal, carbon is
Speaker 3: a metal, neon is a metal. It's well, it's an
Speaker 3: archaic naming convention from the early days of spectroscopy, honestly,
Speaker 3: but it still serves a very practical mathematical purpose for us.
Speaker 3: So it allows astrophysicists to define a star's composition using
Speaker 3: just one single parameter, metallicity.
Speaker 2: Got it.
Speaker 3: So those Population three stars we just discussed, they were
Speaker 3: completely metal free, zero metallicity. It manufactured the first metals
Speaker 3: and then scattered them.
Speaker 2: Which then sets the stage for the second generation of stars.
Speaker 2: Population two stars. They form from gas clouds that have
Speaker 2: been slightly polluted by the shrapnel of those first supernovae,
Speaker 2: And that brings us to our star sdss J zero
Speaker 2: seven one five seven three three four.
Speaker 3: Exactly. It is a second generation star.
Speaker 2: It formed right out of the immediate wreckage of those
Speaker 2: first massive explosions, which makes it what over thirteen billion
Speaker 2: years old right around there? Yes, okay, wait, I'm doing
Speaker 2: the math in my head here, and I'm seeing a
Speaker 2: gaping structural contradiction in what we just talked about.
Speaker 3: Oh, laid on me.
Speaker 2: You just laid out the physics. A star forming from
Speaker 2: metal free or nearly metal free gas has to be
Speaker 2: incredibly massive to overcome thermal pressure because it doesn't have
Speaker 2: the thermal exhaust fence correct and because it's massive, it
Speaker 2: burns extremely hot and blows up in a few million years.
Speaker 2: So if sdss J zero seven one five seven three
Speaker 2: three four formed in an environment with almost no metals,
Speaker 2: why didn't it blow up twelve point nine billion years ago?
Speaker 2: How is a thirteen billion year old low metal star
Speaker 2: still sitting there quietly fused and hydrogen today? It shouldn't exist.
Speaker 3: That paradox right there, That is exactly why this store
Speaker 3: is considered a holy grail in astrophysics. You've hit the
Speaker 3: nail on the head. Its mere existence challenges the standard
Speaker 3: models of early star formation.
Speaker 2: So what's the workaround? How did it survive?
Speaker 3: The answer lies in the highly localized mechanics those first supernovae.
Speaker 3: When a massive population third star exploded, it didn't just
Speaker 3: passively scatter metals. It generated massive, violent.
Speaker 2: Shockwaves, okay, shock waves.
Speaker 3: And these shockwaves slammed into surrounding uncollapsed clouds of that
Speaker 3: pristine gas. The mechanical compression from the shockwave forced the
Speaker 3: gas together so rapidly that it basically bypassed the Thumble
Speaker 3: pressure bottleneck entirely.
Speaker 2: Oh wow. So the shockwave did the work that gravity
Speaker 2: couldn't do alone.
Speaker 3: Exactly, It forced the gas to fragment into much smaller
Speaker 3: clumps before it ignited, and this allowed the second generation
Speaker 3: of stars to form with significantly lower masses, even without
Speaker 3: the cooling benefits of those heavy metals.
Speaker 2: That is wild incredible.
Speaker 3: So sdss J zero seven one five seven three three
Speaker 3: four is a low mass star. It's actually likely less
Speaker 3: massive than our own Sun. And because it has such
Speaker 3: low mass, its core is under far less gravitational pressure.
Speaker 2: So it doesn't have to burn hot to fight back.
Speaker 3: Right the nuclear engine add its core only have to
Speaker 3: like idle to push back against gravity. It just SIPs
Speaker 3: its hydrogen fuel at an incredibly slow rate.
Speaker 2: So while its massive first generation parents redline their engines
Speaker 2: and exploded in millions of years, this tiny low mass
Speaker 2: descendant has just been quietly simmering on low heat for
Speaker 2: the entire history of the universe.
Speaker 3: Simmering, yes, and preserving the exact chemical fingerprint of the
Speaker 3: gas cloud it was born from. That's the case.
Speaker 2: How does it preserve It doesn't the fusion in the
Speaker 2: core mess up the chemistry.
Speaker 3: You'd think so, but no, the outer envelope of a
Speaker 3: low mass star doesn't actually mix deeply with the nuclear
Speaker 3: furnace down at its core. The surface layers were made
Speaker 3: of pristine, unadulterated sample of the environment present just moments
Speaker 3: after the first.
Speaker 2: So it really is a true cosmic fossil.
Speaker 3: Record, perfect time capsule.
Speaker 2: Well, let's get into the actual anatomy of this fossil,
Speaker 2: because the measurements of sdss J zero seven one five
Speaker 2: seven three three four are pretty mind bending. When we
Speaker 2: say the star is pristine. We are talking about a
Speaker 2: fractional trace of metals that borders on undetectable.
Speaker 3: Right, yes, extremely minute quantities.
Speaker 2: It has less than point zero zero five percent of
Speaker 2: the metal content found in our modern sun. Less than
Speaker 2: point zero zero zero five percent.
Speaker 3: It's almost nothing.
Speaker 2: It is twice as metal pore as the previous record holder.
Speaker 2: But the most important metric, the one that really blew
Speaker 2: people away, is its iron content. It is a staggering
Speaker 2: forty times more iron pore than the most pristine star
Speaker 2: previously documented in astronomical catalogs. Forty times.
Speaker 3: Yeah, that iron scarcity is the defining metric here. Why iron, specifically,
Speaker 3: because iron is the absolute endpoint of standard stellar nucleosynthesis.
Speaker 3: A star confuse lighter elements together to release energy right
Speaker 3: the alium in to carbon carbon into oxygen fuse. Iron
Speaker 3: actually consumes more energy than it produces.
Speaker 2: Which is a fatal flaw for a star.
Speaker 3: Exactly when a star tries to fuse iron, the energy
Speaker 3: output drops, gravity winds, and that is what triggers the
Speaker 3: core collapse. Because iron is produced in such vast quantities
Speaker 3: by the supernovae, its abundance in a star's atmosphere acts
Speaker 3: as a highly reliable clock for cosmic.
Speaker 2: Evolution, like counting tree rings almost sort of.
Speaker 3: Yeah, the more iron a star has, the more generations
Speaker 3: of supernovae preceded its birth. It's a measure of how polluted.
Speaker 2: The gas was, which makes sense. I mean, our modern
Speaker 2: sun formed roughly four point six billion years ago, right,
Speaker 2: so it was born from a nebula that had been
Speaker 2: heavily enriched by thousands, maybe millions of supernova cycles over
Speaker 2: billions of years. It's a highly complex chemical stew, very complex.
Speaker 3: So to find a star with an iron content forty
Speaker 3: times lower than the previous extreme, yeah, I mean it
Speaker 3: means stss JAY zero seven one five seven three three
Speaker 3: four formed from a pocket of gas that was almost
Speaker 3: entirely isolated.
Speaker 2: Like a completely untouched bubble.
Speaker 3: Exactly. It was touched by the ejecta of perhaps one
Speaker 3: single specific population three supernova, just one, and then the
Speaker 3: star lock that material away and hasn't changed since.
Speaker 2: That's incredible. But there is another crucial chemical marker here
Speaker 2: that makes this discovery unprecedented. Isn't there carbon?
Speaker 3: Yes? The carbon anomaly is huge.
Speaker 2: Let's dig into that, because usually when astronomers find extremely
Speaker 2: metal poor stars, they are weirdly rich in carbon. Is
Speaker 2: that right?
Speaker 3: You're exactly right. We call them carbon enhanced metal poor stars,
Speaker 3: or CEMP stars. Most of the ancient iron pore stars
Speaker 3: we find have these surprisingly high ratios of carbon in them.
Speaker 2: Why would they have so much carbon if everything else
Speaker 2: is missing?
Speaker 3: Well, this led astrophysicists to hypothesize that early in the universe,
Speaker 3: carbon fine structure line emission, basically carbon radiating heat away,
Speaker 3: was the primary cooling mechanism that allowed these low mass
Speaker 3: stars to form. The prevailing theory was that you absolutely
Speaker 3: needed an overabundance of carbon to cool the gas enough
Speaker 3: to make a small star like this one.
Speaker 2: But stss J zero seven one, five seven through three
Speaker 2: four shatters that model entirely, doesn't.
Speaker 3: It completely shatters it. It is exceptionally low abundances of
Speaker 3: both iron and carbon. According to the carbon cooling theory,
Speaker 3: this star physically should not exist.
Speaker 2: So what does that mean for the science?
Speaker 3: Its mere existence forces theorists right back to the drawing board.
Speaker 3: It proves that other mechanisms, like that mechanical shockwave compression
Speaker 3: we discussed earlier, or perhaps dust driven cooling pathways, we're
Speaker 3: capable of forming low mass stars. In the very earliest
Speaker 3: step box without needing high carbon. It's tangible proof exactly.
Speaker 3: You know, we rely on these incredibly complex supercomputer hydrodynamic
Speaker 3: simulations to model the early universe. We input all the physics,
Speaker 3: we hit play, and we see what the simulation predicts
Speaker 3: a first generation supernova should produce. But finding a physical
Speaker 3: star like this, it takes those models out of the
Speaker 3: realm of pure theory.
Speaker 2: You can actually check the math.
Speaker 3: We can look at the precise chemical ratios in its
Speaker 3: atmosphere and say with confidence, this the exact distribution of
Speaker 3: elements matches the nucleosynthetic yield of an asymmetrical explosion of
Speaker 3: a sixty solar mass population three star. It is empirical
Speaker 3: ground truth.
Speaker 2: Which really highlights the monumental challenge of actually finding empirical
Speaker 2: ground truth in the first place. I mean, let's talk
Speaker 2: about the logistics of this. The Milky Way galaxy contains
Speaker 2: somewhere between what one hundred and four hundred billion.
Speaker 3: Stars that's the current estimate.
Speaker 2: Yeah, and the vast overwhelming majority of them are modern,
Speaker 2: highly metallic stars like our sun. They are noisy, they
Speaker 2: are bright, and they are everywhere. So how do you
Speaker 2: find one single faint, low mass star with a zero
Speaker 2: point zero five percent metal content hiding in a sea
Speaker 2: of hundreds of billions of heavy metal descendants.
Speaker 3: Well, I can tell you you definitely don't do it
Speaker 3: by peering through an eyepiece on your back porch and
Speaker 3: just getting lucky.
Speaker 2: Right. It's a bit more involved than that, just a bit.
Speaker 3: You do it with industrial scale, highly automated stellar demographics.
Speaker 3: The methodology here is amazing. It relies on an interconnected
Speaker 3: ecosystem of observatories operating in tandem and the primary net
Speaker 3: the big sweep is cast by the Sloan Digital Sky
Speaker 3: Survey V, which is currently directed by the astrophysicist Juna
Speaker 3: Colemeyer right SDSSV.
Speaker 2: And it's important to note this isn't taking pretty full
Speaker 2: color pictures of nebulae for desktop background. No, it's a
Speaker 2: massive spectroscopic survey. They are taking the optical and infrared
Speaker 2: spectra of millions of stars simultaneously using these robotic fiber positioners.
Speaker 3: Which is a monumental engineering feat in itself. But we
Speaker 3: need to explain how high resolution spectroscopy actually extracts this
Speaker 3: information because it's not intuitive, Okay, laid out for us obviously,
Speaker 3: We can't send a probe eighty thousand light years away
Speaker 3: to scoop up some plasma in a jar and bring
Speaker 3: it back to a lab. We have to decode the
Speaker 3: starlight itself. When the light from sdss JAY zero seven
Speaker 3: one five seven three three four finally reaches Earth, it
Speaker 3: is a composite of every single wavelength emitted by its hot.
Speaker 2: Surface, a full rainbow of light.
Speaker 3: Right. But as that light pass asses through the star's
Speaker 3: cooler outer atmosphere on its way out, the atoms in
Speaker 3: that atmosphere absorb very specific frequencies.
Speaker 2: Of light, depending on the element, Right, Like an electron
Speaker 2: in an iron atom will absorb a photon of a
Speaker 2: very specific wavelength to jump to a higher energy state.
Speaker 3: Precisely, the physics of quantum mechanics dictates that an atom
Speaker 3: can only absorb exact, discrete packets of energy. So when
Speaker 3: you take that incoming starlight and run it through a spectrograph,
Speaker 3: you spread it out into a continuum a rainbow. But
Speaker 3: wherever an atom in the star's atmosphere absorbed a photon,
Speaker 3: there is a dark gap in the spectrum.
Speaker 2: An absorption line or a frontoffer line.
Speaker 3: Yes, and when you look at it It literally looks
Speaker 3: like a highly complex bar code. The depth and the
Speaker 3: width of those dark lines in the bar code tell
Speaker 3: you exactly how much of a specific element is present
Speaker 3: in that star's atmosphere.
Speaker 2: But capturing a high resolution spectrum where you can measure
Speaker 2: the width of an absorption line down to like fractions
Speaker 2: of an angstrum just to detect a point zero zero
Speaker 2: five percent metal trace takes significant telescope time.
Speaker 3: Doesn't it, Oh an enormous amount of time.
Speaker 2: You can't just spend hours exposing the sensor for every
Speaker 2: single star in the Milky Way. You'd never finish.
Speaker 3: That's exactly the bottleneck, and this is why SDSSV operates
Speaker 3: as the wide net filter. They use telescopes like the
Speaker 3: DuPont at the Los Compoundents Observatory down in Chile and
Speaker 3: the Apache Point Observatory up in New Mexico. These telescopes
Speaker 3: take lower resolution spectrum of millions.
Speaker 2: Of stars, so they basically map the haystack.
Speaker 3: First, Yes, they map the haystack. Then they have algorithms scan.
Speaker 3: They're resulting millions of low res barcodes looking for candidates
Speaker 3: that seem well unusually smooth stars that are conspicuously lacking
Speaker 3: the deep distinct troughs where iron and carbon lines normally
Speaker 3: should be.
Speaker 2: So the algorithms identify the anomalies and once they have
Speaker 2: a list of targets that look highly suspicious, they hand
Speaker 2: those coordinates over to the heavy artillery for conformation.
Speaker 3: Exactly, and the heavy artillery in this specific case is
Speaker 3: the Magellan Clay telescope. This is a massive six point
Speaker 3: five meter instrument also look a Lost Components in Chile.
Speaker 3: But the key isn't just the sheer size of the
Speaker 3: mirror gathering that faint light. It's the instrument attached to
Speaker 3: the back of it, the mic spectrograph.
Speaker 2: Right MIC, which stands for Magellan in Amory Kyocera. A shell. Yes,
Speaker 2: a shell spectrographs are incredible because there are a massive
Speaker 2: leap beyond just shining light through a simple prism.
Speaker 3: Right, oh, absolutely, and a shell grading is an absolute
Speaker 3: marvel of optical engineering. Think about it. If you just
Speaker 3: spread the light out in one long, continuous band to
Speaker 3: get super high resolution, you would need a physical sensor
Speaker 3: that was literally meters long to capture it.
Speaker 2: All, which is impossible to build or cool.
Speaker 3: Right, So instead, and a shell spectrograph uses especially ruled
Speaker 3: diffraction grading to basically overlap multiple high resolution spectra on
Speaker 3: top of each other, and then a second optical element,
Speaker 3: a cross disperser, separates them out vertically.
Speaker 2: Okay, so it effectively takes an incredibly long, detailed barcode,
Speaker 2: chops it up and packs it into a tightly stacked
Speaker 2: two dimensional grid that perfectly fits onto a square digital
Speaker 2: CCD sensor.
Speaker 3: That's exactly what it does, and the resulting resolving power
Speaker 3: is phenomenal. It allows astronomers to zoom in on the
Speaker 3: exact wavelengths where heavy metals absorb light and measure the tiniest,
Speaker 3: almost imperceptible dips in the.
Speaker 2: Signal so they can see the faintest traces.
Speaker 3: Yes, and when they pointed the Magellan telescope at sdss
Speaker 3: J zero seven one five seven three three four and
Speaker 3: process the data through the mic spectrograph, the resulting spectrum
Speaker 3: wasn't just metal poor. It completely confirmed the star as
Speaker 3: the new gold standard for stellar purity, the new baseline.
Speaker 3: But and this with a story gets really crazy. The
Speaker 3: data analysis didn't stop it just its chemistry. They cross
Speaker 3: reference the star with astrometric data, which uncovered the most
Speaker 3: structurally bizarre aspect of this entire discovery.
Speaker 2: Yes, the European Space Agency's Gay emission. This is where
Speaker 2: it gets so cool. For context, GAIA is an observatory
Speaker 2: positioned out at lagrange point two far away from Earth,
Speaker 2: and its entire purpose.
Speaker 3: Is astrometry precision astrometry. Right.
Speaker 2: It precisely measures the positions, the distances, and the motions
Speaker 2: of over a billion stars in our galaxy with micro
Speaker 2: arc second precision. They literally map the exact three D
Speaker 2: velocity vectors of these stars. And when they looked at
Speaker 2: the kinematics the physical movement through space of our pristine
Speaker 2: little star, the vectors didn't align with the Milky Way.
Speaker 3: It was a kinematic outlier, completely off book.
Speaker 2: It was moving wrong.
Speaker 3: Yeah. The tracking data chartting gets highly eccentric ORBET allowed
Speaker 3: them to trace its trajectory backward through time, and it
Speaker 3: revealed that as DSSG zero seven one five seven three
Speaker 3: three four, which is currently residing roughly eighty thousand light
Speaker 3: years away in the Milky Way's halo, is an ancient immigrant.
Speaker 2: It wasn't born in our galaxy.
Speaker 3: No, the orbital mechanics point its origin all the way
Speaker 3: back to the large Magellanic cloud. Which is a massive
Speaker 3: satellite galaxy that currently orbits the Milky Way.
Speaker 2: Okay, wait, let's pause and really think about this. Here's
Speaker 2: where it gets really interesting. It's one thing to find
Speaker 2: a needle in a haystack. It's another to realize the
Speaker 2: needle came from a completely different farm. This star was
Speaker 2: forged in the primordial gas of a completely different galaxy,
Speaker 2: survived for billions of years, and then was physically dragged
Speaker 2: across the intrigalactic void into our own galaxy. How does
Speaker 2: the architecture of a star survive that?
Speaker 3: It's hard to conceptualize.
Speaker 2: The distances involved are staggering, and the gravitational sheer forces
Speaker 2: of interacting galaxies must be incredibly intense. How does a tiny,
Speaker 2: low mass star get ripped out of the large magellanic cloud,
Speaker 2: pulled into the Milky Way and just completely avoid being
Speaker 2: shredded by tidal forces or swallowed by the chaotic center
Speaker 2: of our galaxy.
Speaker 3: It's a great question because it feels intuitive to imagine
Speaker 3: galactic interactions as these incredibly violent chaotic collisions, like two
Speaker 3: solid objects smashing together at high speed with sparks flying
Speaker 3: in total destruction everywhere.
Speaker 2: Like car crashes in space, right, But we really.
Speaker 3: Have to recognize the sheer, terrifying scale of empty space.
Speaker 3: Within a galaxy, the distance between individual stars is so
Speaker 3: vast that the physical volume of the star itself is
Speaker 3: practically a rounding error compared to the void.
Speaker 2: Around it, So they don't actually hit each other almost never.
Speaker 3: When galaxies interact, or when the Milky Way strips material
Speaker 3: from a satellite galaxy like the Magellanic Cloud, the stars
Speaker 3: themselves do not collide. They essentially pass through the opposing
Speaker 3: galaxy structure like ghosts.
Speaker 2: Like ghosts, just passing right through exactly.
Speaker 3: The interactions are purely gravitational. The Milky Way has an
Speaker 3: immense dark matter halo and a massively deep gravitational well,
Speaker 3: so as a large Magellanic cloud orbits us, the gravitational
Speaker 3: gradient of the Milky Way pulls on the side of
Speaker 3: the cloud closest to it with slightly more force than
Speaker 3: the far.
Speaker 2: Side, and that scratches it.
Speaker 3: Yes, this differential poll creates what we call tidal shear.
Speaker 3: Over hundreds of millions of years, this shear gently strips
Speaker 3: streams of gas and stars away from the smaller galaxy.
Speaker 2: Wow, it's literally galactic cannibalism. But like very slow cannibalism.
Speaker 3: Very slow, our star was simply caught in one of
Speaker 3: those tidal screens. It wasn't violently yanked. It was slowly
Speaker 3: gradually drawn out of its local orbit within the Magellanic cloud,
Speaker 3: and it entered a new elongated orbit, just falling into
Speaker 3: the gravity well of the Milky Way.
Speaker 2: But the star itself isn't torn apart by that pole.
Speaker 3: No, because the star's own internal gravity, the very force
Speaker 3: maintaining that hydrostatic equilibrium we talked about earlier, is vastly
Speaker 3: stronger than the external title forces gently pulling at its surface.
Speaker 3: So the physical structure of the star is entirely unbothered.
Speaker 3: It just sails smoothly along the curvature of space time,
Speaker 3: quietly transferring from one galactic hoose to another.
Speaker 2: The mechanics of that journey are just staggering. To think
Speaker 2: about a drop of distilled water from the dawn of
Speaker 2: time surviving a thirteen billion year weight, only to be
Speaker 2: ferried completely intact across the void of space into our
Speaker 2: cosmic backyard.
Speaker 3: It's poetic, really, it is.
Speaker 2: And the fact that we were able to detect it,
Speaker 2: analyze its chemistry down to a fraction of refeent and
Speaker 2: trace its orbital history backward. I mean it brings us
Speaker 2: to the human element of this deep dive, which is
Speaker 2: maybe the best part. The realization of exactly who was
Speaker 2: sitting in the control room when this data came down
Speaker 2: from the Magellan telescope.
Speaker 3: Yes, because the scientific discovery itself is profound, but the
Speaker 3: sociological context of how it happened that is what makes
Speaker 3: this a real landmark moment for astrophysics education.
Speaker 2: Because the data wasn't cracked by an isolated team of
Speaker 2: tenured professors working in a locked lab for five years.
Speaker 3: No, it wasn't. It was the ultimate college spring break trip.
Speaker 2: Alexander g a professor at the University of Chicago and
Speaker 2: a former post doctoral fellow at Carnegie Observatories, brought a
Speaker 2: group of his undergraduate students to the Lost compoundas observatory
Speaker 2: in Chile. This was quite literally the fieldwork component of
Speaker 2: his class in astrophysics.
Speaker 3: We really have to set the scene to understand the
Speaker 3: impact of this for those students. The Lost Components Observatory
Speaker 3: sits at an altitude of nearly eight thousand feet in
Speaker 3: the Atacama Desert, so the air is thin in the
Speaker 3: air is incredibly dry, the atmospheric seeing is among the
Speaker 3: absolute best on the planet, and you are surrounded by
Speaker 3: some of the most sensitive advanced optical instruments ever engineered
Speaker 3: by humanity. For an undergraduate student, just being physically present
Speaker 3: in that facility is overwhelming.
Speaker 2: I can imagine on their first night on the mountain,
Speaker 2: they visit the DuPont telescope and they are really just
Speaker 2: observing the observers. They watch the technicians running the SDSSV
Speaker 2: survey taking in that wide net low resolution data filtering
Speaker 2: the haystack. It's essentially an observational tutorial, a warm up, right,
Speaker 2: But the very next evening, the undergraduates actually transition to
Speaker 2: the six point five meter Magellan Clay telescope. They step
Speaker 2: up to the plate.
Speaker 3: They were utilizing the mica shell spectrograph specifically targeting the
Speaker 3: anomalies flagged by the sdss data. And the process of
Speaker 3: raw data reduction in real time is intense.
Speaker 2: What does that actually look like?
Speaker 3: Well, when the CCD sensor reads out the data, you
Speaker 3: don't instantly see a clean RAF on your screen. You
Speaker 3: have to subtract the electronic noise of the sensor itself.
Speaker 3: You have to remove the atmospheric teleric lines from Earth's
Speaker 3: own atmosphere, flat feel the image, and then carefully calibrate
Speaker 3: the wavelength pixel by pixel.
Speaker 2: And the students are in the control room doing this
Speaker 2: computational heavy lifting in the wee hours of the morning exactly.
Speaker 2: I mean, most college students on spring break are engaged
Speaker 2: in entirely different chemical analyzes at three boort am fearpoint,
Speaker 2: but these undergrads are running the reduction scripts. They pull
Speaker 2: the calibrated spectrum up on the monitor and they see
Speaker 2: the physical evidence staring back at them.
Speaker 3: They are looking at the specific wavelengths where elements normally
Speaker 3: absorb light. They check the three hundred pety three angstrum
Speaker 3: line for calcium, They check the g ban for molecular carbon.
Speaker 3: They look at the dense cluster of iron lines around
Speaker 3: three teen hundred and eight hundred and fifty nine angkstrums,
Speaker 3: and what do they say? Instead of seeing deep, prominent
Speaker 3: absorption troughs, they see continuum. They just see a nearly
Speaker 3: flat line. The metals simply aren't there.
Speaker 2: In real time. At three point am, they verify that
Speaker 2: they are looking at the most metal poor star ever recorded,
Speaker 2: a thirteen billion year old cosmic fossil from another galaxy,
Speaker 2: and the reaction from Professor Alexander G honestly perfectly encapsulates
Speaker 2: a massive shift in how astrophysics is being taught right now.
Speaker 3: It really does. Judah Colemeyer, who directs the STSSV project,
Speaker 3: champions a very specific pedagogical philosophy. She argues heavily against
Speaker 3: the traditional model, where undergraduate science basically consists of repeating
Speaker 3: centuries old lab experiments where the answer is already printed
Speaker 3: in the back of.
Speaker 2: The textbook, which is how most of us learned science right.
Speaker 3: But with the sheer volume of high quality data being
Speaker 3: generated by these automated surveys today, she advocates for what
Speaker 3: she calls a curriculum of discovery. The philosophy is that
Speaker 3: students should be thrust directly onto the bleeding edge of science,
Speaker 3: working with raw, unanalyzed data, where actual breakthroughs are a
Speaker 3: structural expectation, not just a weird anomaly.
Speaker 2: And Alexander G live that philosophy right now then in
Speaker 2: there at three am in the control room, once the
Speaker 2: discovery was confirmed, he didn't just log it in a
Speaker 2: notebook and move back to the planned syllabus for the
Speaker 2: next day.
Speaker 3: No, he threw the syllabus out.
Speaker 2: He threw it out. He completely reconfigured the remainder of
Speaker 2: the semester's coursework around this single discovery.
Speaker 3: Because he sees the moment to teach the most critical
Speaker 3: unteachable skill in the scientific method, flexibility. When the data
Speaker 3: presents an anomaly, you abandon your preconceptions, drop the rigid schedule,
Speaker 3: and you just follow the empirical evidence wherever it leads.
Speaker 2: That's real science, it is the.
Speaker 3: Student spent the rest of the term analyzing the stellar
Speaker 3: atmosphere models, running the nucleosynthesis yields, and actually drafting the
Speaker 3: peer reviewed findings.
Speaker 2: Imagine stepping back onto campus after that spring break, the
Speaker 2: quintessential college experience of returning to the dorms, and when
Speaker 2: someone asked, Hey, how is your trip, you have to
Speaker 2: casually explain that you spent the week fundamentally rewriting the
Speaker 2: bounds of early galactic nucleosynthesis and identifying an ancient extragalactic
Speaker 2: immigrant star hiding in the Milky Way halo.
Speaker 3: It's quite the icebreaker.
Speaker 2: It bridges the gap between incomprehensible cosmic scales and tangible
Speaker 2: human curiosity, and.
Speaker 3: It creates a self sustaining loop of scientific inquiry. By
Speaker 3: placing undergraduates at the helm of a six point five
Speaker 3: meter telescope and allowing them to experience the visceral shock
Speaker 3: of unfiltered discovery, you cement their trajectory in the field forever.
Speaker 3: They aren't just passively learning astrophysics. They're actively generating the
Speaker 3: astrophysics that subsequent generations will study.
Speaker 2: The oldest, most pristine matter in the known universe being
Speaker 2: untangled and decoded by the youngest, newest generation of scientists.
Speaker 2: It's a profound synthesis of time, technology, and human drive.
Speaker 3: I couldn't set it better myself.
Speaker 2: I mean, just look at the journey we've taken today.
Speaker 2: We started thirteen point eight billion years ago, navigating the opaque,
Speaker 2: superheated plasma of the epoch of recombination. We track the
Speaker 2: thermodynamics of the first massive population three stars, watching them
Speaker 2: wage a losing battle against gravity without the cooling aid
Speaker 2: of heavy metals, and we.
Speaker 3: Saw their rapid, violent demise forge the first trace elements
Speaker 3: in the universe.
Speaker 2: Right and from the localized shockwaves of those first supernovae,
Speaker 2: the mechanics of star formation shifted, allowing lower mass stars
Speaker 2: to form and survive. Sdss J zero seven one five
Speaker 2: seven three three four condensed out of that ancient debris,
Speaker 2: locking an impossibly pure low carbon, low iron chemical fingerprint
Speaker 2: into its atmosphere.
Speaker 3: We traced its gravitational dynamics as it formed in the
Speaker 3: large Magellanic Cloud, only to be ensnared by the immense
Speaker 3: tidal forces of the Milky.
Speaker 2: Way, slowly spiraling across the intergalactic void via dynamical friction
Speaker 2: to settle quietly into our own halo, and we witness
Speaker 2: the massive interconnected architecture of modern astronomy required to even
Speaker 2: find it.
Speaker 3: The statistical dragnet of the Sloane Digital Sky Survey.
Speaker 2: The robotic fiber positioners, the micro arc second astrometry of
Speaker 2: the guyasatellite mapping its kinematic orbit, and the sheer resolving
Speaker 2: power of the pike Ashell spectrographed on the Magellan Telescope,
Speaker 2: overlapping high resolution light waves onto a two D sensor
Speaker 2: to measure elemental abundances down to the milli angstrum, all
Speaker 2: of it culminating in a control room in the high
Speaker 2: Chilean desert with a group of undergrads.
Speaker 3: It forces a massive paradigm shift in how you view
Speaker 3: the night sky. The light hitting your retina isn't just
Speaker 3: a spatial map, it's a temporal one. You are looking
Speaker 3: at layers of cosmic time existing simultaneously.
Speaker 2: Like looking down a time tunnel exactly.
Speaker 3: The discovery of STSSJ zero seven one five seven three
Speaker 3: three four provides empirical validation for our hydrodynamic models of
Speaker 3: early universe nucleosynthesis. But more importantly, it proves the limitations
Speaker 3: of our current models, particularly regarding carbon cooling. It proves
Speaker 3: that the structure of the cosmos still hold fundamental anomalies
Speaker 3: that defire expectations.
Speaker 2: Which brings us right back to that perfectly preserved model
Speaker 2: t forward idling on the NEONLTZ super Highway. It survived
Speaker 2: the chaotic restructuring of a galaxy hiding right in plane sight.
Speaker 2: Low mass, thirteen billion year old star forged in a
Speaker 2: completely different galaxy, can survive tidal stripping and migrate into
Speaker 2: the Milky Way, perfectly disguised among billions of heavy metal descendants.
Speaker 2: What other kinematic ghosts are out there?
Speaker 3: That is the million dollar question.
Speaker 2: What impossible anomalies rogue stars from entirely dissolved satellite galaxies,
Speaker 2: or remnants of the very first epoch of light are
Speaker 2: currently sailing right above our heads, just waiting for the
Speaker 2: right telescope and the right curious mind to finally look
Speaker 2: closely enough