Speaker 1: Welcome to Bedtime Astronomy. Explore the wonders of the cosmos
Speaker 1: with our soothing Bedtime Astronomy podcast. Each episode offers a
Speaker 1: gentle journey through the stars, planets, and beyond, perfect for
Speaker 1: unwinding after a long day. Let's travel through the mysteries
Speaker 1: of the universe as you drift off into a peaceful
Speaker 1: slumber under the night sky.
Speaker 2: Welcome back to the show. Today, we are we're going
Speaker 2: to fundamentally change the way you look at the sky.
Speaker 3: Yeah, literally, the actual physical sky you see every day.
Speaker 2: Right, And I don't mean that in you know, some
Speaker 2: kind of metaphorical reach for the stars kind of way.
Speaker 2: I mean literally, we are talking about the Sun, the.
Speaker 3: Sun skull, our local.
Speaker 2: Star, right. And I know the immediate reaction might be, Okay,
Speaker 2: the Sun. It's big, it's hot, it rises in the east,
Speaker 2: sets in the west, and if I stare at it.
Speaker 3: I go blind, which you should not do.
Speaker 2: No, absolutely do not do that. But we tend to
Speaker 2: take it for granted. I think it's just it's the
Speaker 2: background lighting for our lives. But in the world of astronomy,
Speaker 2: the sun isn't just a light bulb. It is a key,
Speaker 2: like a literal skeleton key that unlocks the physics of
Speaker 2: the entire universe. It really is.
Speaker 3: It's the Rosetta stone of astronomy. That's really the core
Speaker 3: concept we are unpacking today for you. It's the only
Speaker 3: star in the universe that doesn't look like a dot.
Speaker 2: Yeah, and we have a massive stack of research to
Speaker 2: get through today. This is primarily centering on a major
Speaker 2: review paper by Shintoriomi and his colleagues, and the mission
Speaker 2: of this exploration today is to understand how scientists are
Speaker 2: using our Sun, the only star we can actually see
Speaker 2: in high definition, to decode the blurry, pixelated signals we
Speaker 2: get from every other star in the galaxy.
Speaker 3: Exactly. It's really about bridging the gap between solar physics,
Speaker 3: which is the study of our specific star, and stellar physics,
Speaker 3: which is the study of all those other points of light. Historically,
Speaker 3: these have been two totally separate fields, but now they
Speaker 3: are emerging.
Speaker 2: So let's start with the big picture. You mentioned the
Speaker 2: problem of distance earlier when we were chatting. I think
Speaker 2: we need to really settle into this idea to understand
Speaker 2: why this research is so crucial.
Speaker 3: Think about this when you look up at the night
Speaker 3: sky or even when we use our most powerful tools,
Speaker 3: you know the James Web Space Telescope, PUBBLE, those massive
Speaker 3: ground based observatories down in Chile. What do we actually
Speaker 3: see when we look at a star?
Speaker 2: I mean, even with the best zoom lenses in human history,
Speaker 2: we basically just see a.
Speaker 3: Dot, a pixel precisely, we call it a point source.
Speaker 3: We can analyze the light coming from that point. We
Speaker 3: can break it into a spectrum to see what it's
Speaker 3: made of. We can measure if it gets brighter or
Speaker 3: dimmer over time. But we cannot resolve the surface. We
Speaker 3: can't see the geography.
Speaker 2: The actual physical features, right.
Speaker 3: We can't see the storms. We can't see the sun
Speaker 3: spots or the flares directly. It is just a single
Speaker 3: pixel of data that contains all that information just meshed together.
Speaker 2: It's like it's like trying to understand the complexity of
Speaker 2: New York City by looking at a single light bulb
Speaker 2: on the Empire State building from space.
Speaker 3: That's great analogy. Now can we hear that to the sun?
Speaker 3: The Sun is close, we can see its eyelashes. Practically,
Speaker 3: we can see sun spots the size of Earth. We
Speaker 3: can see giant loops of magnetic plasma arching over the surface.
Speaker 3: We can see solar flares exploding in real time.
Speaker 2: It's basically high definition four K video of the Sun's surface.
Speaker 3: Yeah, exactly. So the Rosetta Stone analogy here is all about.
Speaker 2: Translation, right, because the original Zetta Stone allowed us to
Speaker 2: translate Egyptian hieroglyphs, which were a total mystery because we
Speaker 2: had the exact same text written in Greek, which we
Speaker 2: already understood exactly.
Speaker 3: The Sun is our Greek text. We know what the
Speaker 3: Sun looks like up close. We understand the physics of
Speaker 3: the surface because we can actually see it happening.
Speaker 2: And the higherglyphs are the distant stars.
Speaker 3: Right. We take the hdview of our Sun and we
Speaker 3: mathematically downgrade it. We blur it on purpose. We turn
Speaker 3: our Sun into a single pixel to see what it
Speaker 3: would look like if it were, you know, fifty light
Speaker 3: years away.
Speaker 2: Oh wow.
Speaker 3: Yeah, And by comparing the HD version, what we absolutely
Speaker 3: know is happening with the pixel version the signal we
Speaker 3: would receive. We learn how to read the signals from
Speaker 3: other stars.
Speaker 2: That is incredibly cool. We are basically training ourselves on
Speaker 2: the Sun so we can play detective with stars that
Speaker 2: are hundreds of light years away. We're building a dictionary
Speaker 2: of stellar signals.
Speaker 3: That is exactly it. And the primary tool for this
Speaker 3: investigation are magnifying glass if you will, is a spacecraft
Speaker 3: called the SDO.
Speaker 2: NASA's Solar Dynamics Observatory.
Speaker 3: Yes, launch back in twenty ten. And before we get
Speaker 3: into the actual results, I think we really need to
Speaker 3: pause on the SDO itself because calling it a camera feels, well,
Speaker 3: it feels like a bit of an insult to the
Speaker 3: engineering involved.
Speaker 2: I agree completely. Reading the specs on this thing, it's
Speaker 2: an absolute beast. It's not just taking snapshots for Instagram.
Speaker 2: It's a suite of three very specific, very sophisticated instruments.
Speaker 3: It's like having an X ray machine, an MRI, and
Speaker 3: a thermal camera all pointed at the exact same patient simultaneously.
Speaker 3: It sees the Sun in layers.
Speaker 2: Okay, let's break down these eyes of the SDO for
Speaker 2: beginning who might not be familiar, because understanding how they
Speaker 2: see is crucial to understand the data we're going to
Speaker 2: discuss later. So the first one is called HMI.
Speaker 3: Right, the Helioseismic and Magnetic Imager. This is the heavy lifter.
Speaker 3: It's not looking at light in the way your film
Speaker 3: camera does. It's specifically measuring the magnetic field at the
Speaker 3: solar surface.
Speaker 2: Now this brings us to the actual physics of it all.
Speaker 2: How do you take a picture of magnetic field? Because
Speaker 2: magnetic fields are invisible.
Speaker 3: Right, They are invisible to the naked eye, Yes, but
Speaker 3: they leave a very specific fingerprint on light. It's called
Speaker 3: the Zeman effect.
Speaker 2: Zeman effect. Okay, let's unpack that for everyone.
Speaker 3: Sure, Imagine you were looking at a specific color of
Speaker 3: light emitted by an iron atom on the sun, a
Speaker 3: spectral line. If that iron atom is just sitting there
Speaker 3: in a calm, quiet region, that line is sharp and singular.
Speaker 3: It's just one line, okay. But if you place that
Speaker 3: iron atom inside a strong magnetic field, like inside a
Speaker 3: sun spot, that single line splits. It literally divides into
Speaker 3: three distinct lines.
Speaker 2: It actually flits the light itself.
Speaker 3: It splits. The energy levels of the electrons in the
Speaker 3: atom are physically shifted by the magnetic field, and the
Speaker 3: amount of splitting how far apart those new lines are
Speaker 3: tells you exactly how strong the magnet is.
Speaker 2: So the HMI instrument is scanning the entire face of
Speaker 2: the Sun millions of times a day looking for this
Speaker 2: tiny microscopic splitting of.
Speaker 3: Light exactly, and by mapping that splitting, it creates what
Speaker 3: we call a magnetogram. It's basically a topographic map of
Speaker 3: the magnetic forces churning on the surface.
Speaker 2: That's the engine room. Because as we know, magnetism drives
Speaker 2: pretty much everything on the Sun.
Speaker 3: It is the puppet master everything interesting, the flares, the spots,
Speaker 3: the giant eruptions, It all starts with the magnetic field
Speaker 3: twisting and snapping. HMI gives us the map of those
Speaker 3: puppet strings.
Speaker 2: Okay, so that's the magnetic map. Then we have the
Speaker 2: glamour shots. The instrument called AIA.
Speaker 3: The atmospheric Imaging assembly. When you see those stunning golden,
Speaker 3: swirling videos of the Sun on the news or in documentaries,
Speaker 3: the ones that look like a living, breathing.
Speaker 2: Ball of yeah, the ones that make you suddenly realize
Speaker 2: the Sun is actually a terrifying object.
Speaker 3: Yeah, that is AIA data. But again, it's not just
Speaker 3: a standard camera taking a color photo. It specifically filters
Speaker 3: light to look at extreme temperatures.
Speaker 2: This is the part that fascinated me in the Toriomi paper.
Speaker 2: It's not looking at colors like red or blue.
Speaker 3: It's looking at ionization, states right, it looks at extreme
Speaker 3: ultraviolet light. At these insane temperatures, atoms literally get stripped
Speaker 3: of their electrons. We call this ionization. So AIA has
Speaker 3: a filter that only lets in light from iron atoms
Speaker 3: that have lost say eight electrons.
Speaker 2: And that specific loss only happens at a specific temperature exactly.
Speaker 3: Iron nine, which is iron that has lost eight electrons,
Speaker 3: glows brightest at about six hundred thousand degrees, but iron
Speaker 3: eighteen might glow at six million degrees. So by mechanically
Speaker 3: switching filters, the AIA can basically peel the onion. It
Speaker 3: can say, show me only the gas that is exactly
Speaker 3: one million degrees, and suddenly you see specific lou and
Speaker 3: structures that are completely invisible at other temperatures.
Speaker 2: So we have the magnetic map from HMI and the
Speaker 2: temperature sliced atmosphere from AIA. And the third one is EVE, the.
Speaker 3: Extreme Ultraviolet Variability Experiment. Unlike the other two, EVE isn't
Speaker 3: taking a picture at all. It's an irradiance sensor. It
Speaker 3: measures the total energy output.
Speaker 2: So it's a giant light meter, a very.
Speaker 3: Very fancy light meter. It tells us exactly how much
Speaker 3: energy the Sun is screaming out into the Solar system
Speaker 3: at any given second across the entire UV spectrum.
Speaker 2: So putting it all together for you listening, HMI shows
Speaker 2: us the cause, which is magnetism, AIA shows us the
Speaker 2: structure of the atmosphere itself, and Eve shows us the output,
Speaker 2: the actual energy hitting us correct.
Speaker 3: And here is why SDO is the absolute foundation of
Speaker 3: this Rosetta Stone project. It has been staring at the
Speaker 3: Sun twenty four to seven for well over a decade.
Speaker 3: It never blinks.
Speaker 2: That is a staggering amount of data.
Speaker 3: It's massive, and crucially, it covers a full solar cycle
Speaker 3: the Sun breathes. Essentially, it has solar maximum where it
Speaker 3: is angry, covered in spots and constantly flaring, and it
Speaker 3: has a solar minimum where it is very quiet and
Speaker 3: virtually blank. SDO captured the entire transition from quiet to
Speaker 3: angry and back again.
Speaker 2: So we have a complete baseline. We noted chill star
Speaker 2: looks like, and we know what a raging star looks
Speaker 2: like in high definition.
Speaker 3: Exactly, and that leads us directly to the core methodology
Speaker 3: of the paper. They call it the Sun is a star. Experiment.
Speaker 2: This is the reverse engineering part. Walk us through how
Speaker 2: they actually perform this experiment.
Speaker 3: It's a brilliant synthesis of data. They take those incredible
Speaker 3: high resolution images from SDO where you can see the
Speaker 3: sun spots and the loops perfectly clearly, and they deliberately
Speaker 3: ruin them.
Speaker 2: They ruin them like blur them out.
Speaker 3: They integrate them. They sum up all the light from
Speaker 3: the entire disc into a single data point. They simulate
Speaker 3: what the Sun would look like if it were a
Speaker 3: pinpoint of light fifty light years away.
Speaker 2: I see. They force the Sun to look like a
Speaker 2: distant star to match the data we get from telescope. Right.
Speaker 3: But and here's the absolute key. They keep the original
Speaker 3: HD footage. So now they have a direct link. They
Speaker 3: can look at the fake star data and say, okay,
Speaker 3: look at this little dip in the light curve, what
Speaker 3: caused that. Then they look at the HD map from
Speaker 3: the same exact moment and say, aha, that dip was
Speaker 3: caused by this specific group of sunspots rotating across the center.
Speaker 2: That is genius. It totally eliminates the guesswork. Instead of
Speaker 2: just theorizing about what a blip on a distant star
Speaker 2: means we have an actual catalog of blips from our
Speaker 2: own sun to compare it to exactly.
Speaker 3: It's building a dictionary, and as we move into decoding
Speaker 3: the light, we find that the translation isn't always as
Speaker 3: straightforward as we might hope. It turns out stars can
Speaker 3: be incredibly tricky.
Speaker 2: Right, So the paper discusses a specific study by Torrio
Speaker 2: me and his team where they watch transit events. Now,
Speaker 2: for the beginners out there, a transit event just means
Speaker 2: something moving across the face of the star as it rotates. Right.
Speaker 3: Yes, the sun rotates roughly once every twenty seven days,
Speaker 3: so if a some spot forms on the left side,
Speaker 3: it will slowly march across the face to the right
Speaker 3: side over the course of about two weeks.
Speaker 2: Let's look at the first case study here, the sun spot.
Speaker 2: In my head, this is simple. A sunspot is a
Speaker 2: dark patch on the surface. It's like a dimmer switch.
Speaker 2: So if a dark patch moves in front of the camera,
Speaker 2: the total light we receive should drop.
Speaker 3: And invisible light the normal light our eyes can see.
Speaker 3: That is exactly what happens when a big sunspot group
Speaker 3: rotates into view. The total brightness of the sun drops
Speaker 3: it creates a measurable dip in the light curve.
Speaker 2: Simple physics, you block the light, it gets darker. But
Speaker 2: the notes say there's a twist here, involving something called foculae.
Speaker 3: There is always a twist in astrophysics. Faculae it's Latin
Speaker 3: for little.
Speaker 2: Torches, little torches. That actually sounds quite poetic. It is.
Speaker 3: Faculae are these bright magnetic regions that usually cluster around sunspots.
Speaker 3: They are like a glowing network of magnetic cracks in
Speaker 3: the surface. Now Here is where the geometry gets weird.
Speaker 3: When a sunspot is right in the middle of the
Speaker 3: sun looking straight at us, the dark spot wins the
Speaker 3: total light dips. But when that sun spot group is
Speaker 3: near the edge of the stone what we call the limb,
Speaker 3: the faculae actually take over.
Speaker 2: Why what does the physical position on the sphere matter.
Speaker 3: It has to do with something called the hot wall effect.
Speaker 2: The hot wall effect. Okay, break that down for us.
Speaker 3: Imagine a facula is like a physical depression in the
Speaker 3: Sun's surface, like a magnetic pothole.
Speaker 2: Okay, I'm picturing a pothole in the street.
Speaker 3: The floor of that pothole is cooler and darker than
Speaker 3: the surrounding area. But the vertical walls of the pothole
Speaker 3: are very hot and very bright.
Speaker 2: Got it.
Speaker 3: If you look straight down into the pothole from when
Speaker 3: it's perfectly in the center of the sun facing Earth,
Speaker 3: you mostly just see the cool, dark floor, so it
Speaker 3: doesn't look very bright to you.
Speaker 2: But if I look at it from a severe angle.
Speaker 3: Exactly as it rotates to the edge of the sun,
Speaker 3: your viewing angle changes drastically. You can no longer see
Speaker 3: the dark floor of the pothole at all. Your line
Speaker 3: of sight hits the vertical, glowing, hot wall of the canyon.
Speaker 3: So suddenly this thing that looked faint or dark becomes
Speaker 3: in predibly bright.
Speaker 2: That is wild. So depending entirely on where the sunspot
Speaker 2: is located on the sphere, the star as a whole
Speaker 2: might look dimmer.
Speaker 3: Or brighter exactly when the active region is on the edge.
Speaker 3: Those faculty a can actually boost the total brightness so
Speaker 3: much that they completely cancel out the darkness of the sunspot.
Speaker 3: So a sunspot signal isn't just a simple dip. It's
Speaker 3: a very complex dance of dipping and brightening depending on
Speaker 3: the viewing angle.
Speaker 2: That definitely complicates things for astronomers looking at other stars.
Speaker 2: If you don't know about the hot wall effect, you
Speaker 2: might completely misinterpret the light data you're receiving.
Speaker 3: You absolutely would, You'd think the star was behaving erratically.
Speaker 3: And it gets even trickier with the second case study,
Speaker 3: the spotless.
Speaker 2: Pledge pledge p lage. That's French for b Trech.
Speaker 3: Yes it is. In solar physics, a plage is basically
Speaker 3: a huge region of magnetic activity, very much like a
Speaker 3: sunspot group, but without the actual dark spot in the middle.
Speaker 3: It's just the bright magnetic network spread out over an area, so.
Speaker 2: It's basically a sunspot ghost. It has all the underlying magnetism,
Speaker 2: but none of the dark core.
Speaker 3: In a way, yes, now here is the kicker. If
Speaker 3: you look at a plage in visible light, you barely
Speaker 3: see it at all because there is no dark spot
Speaker 3: to block the light, and that bright magnetic network is
Speaker 3: just too faint to show up against the overwhelming glare
Speaker 3: of the rest of the Sun, so the visible light
Speaker 3: curve just stays flat.
Speaker 2: So if I'm an alien astronomer looking at our Sun
Speaker 2: with a regular visible light telescope and a massive plage
Speaker 2: rotates by, I just think the Sun is completely quiet.
Speaker 3: You'd think it was fast asleep. You'd write in your
Speaker 3: log no activity today. But if you switch your telescope
Speaker 3: to look an ultraviolet light, that exact same plage lights
Speaker 3: up like a Christmas tree.
Speaker 2: It suddenly becomes visible.
Speaker 3: It totally dominates the view. In UV, the plage is
Speaker 3: screaming with activity. This is one of the most important
Speaker 3: lessons we've learned from the SDEO data. Visible light is
Speaker 3: a terrible, terrible way to measure the true magnetic activity
Speaker 3: of a star. You might look at a star invisible
Speaker 3: light and thing it's boring and safe, But if you
Speaker 3: switch to UV, you realize it's actually raging with massive
Speaker 3: magnetic storms.
Speaker 2: That feels like a very important distinction, especially if we're
Speaker 2: looking for habitable planets around these stars. We'll definitely get
Speaker 2: to the habitability question later, but this idea that a
Speaker 2: star can hide its aggression so to speak, in the
Speaker 2: UV spectrum is a bit unsettling.
Speaker 3: It completely changes how we interpret so called quiet stars
Speaker 3: in our galaxy.
Speaker 2: I want to talk about another geometric puzzle mentioned in
Speaker 2: the research, the time lags. This connects back to the
Speaker 2: three dimensional structure of the Sun.
Speaker 3: This is one of my favorite visualizations from the Toriumi paper.
Speaker 3: It's about fundamentally understanding that the Sun isn't a flat
Speaker 3: disk painted on the sky. It's a sphere, and it
Speaker 3: has an atmosphere that extends far upwards.
Speaker 2: The notes used a skyscraper analogy for this. Walk me
Speaker 2: through it.
Speaker 3: Okay, imagine a giant skyscraper built right on the equator
Speaker 3: of the Earth, and the Earth is rotating.
Speaker 2: Okay, I'm picturing it a massive skyscraper rotating toward me
Speaker 2: over the horizon.
Speaker 3: As that skyscraper rotates over the horizon, coming toward you,
Speaker 3: what part of the building do you see? First?
Speaker 2: I see the top of the tower, first, the antenna
Speaker 2: on the roof right.
Speaker 3: And then a little while later, as it keeps rotating,
Speaker 3: you see the middle floors, and finally you see the
Speaker 3: lobby down at ground level.
Speaker 2: Right. Because the Earth is curved, the top of the
Speaker 2: tower peaks over the horizon before the base does exactly.
Speaker 3: Now apply that exact same logic to the Sun. A
Speaker 3: sunspot is at the ground level the surface or photosphere,
Speaker 3: but above that sunspot, extending high up into the solar
Speaker 3: atmosphere are giant loops of glowing magnetic plasma that's the
Speaker 3: top of the skyscraper the corona.
Speaker 2: So as the sun rotates, we should logically see the
Speaker 2: loops in the atmosphere before we see the actual spot
Speaker 2: on the.
Speaker 3: Surface precisely, and that is exactly what the sdo instruments see.
Speaker 3: We see the ultraviolet signal, which represents the high loops
Speaker 3: rise in intensity, before we see the visible light signal
Speaker 3: the spot dip. There is a clearly measurable time lag
Speaker 3: between the two signals.
Speaker 2: That is fascinating. We are literally measuring the rotation of
Speaker 2: a three dimensional structure.
Speaker 3: And here is why it matters so much for distant stars.
Speaker 3: When we look at a star one hundred light years away,
Speaker 3: we can't see the loops. We can't see the spot.
Speaker 3: We just see lines on a graph. But if we
Speaker 3: observe that the UV light from that star gets bright
Speaker 3: a few hours before the visible light dims.
Speaker 2: We can calculate how tall the skyscraper is.
Speaker 3: Bingo, we can estimate the physical height of the magnetic
Speaker 3: loops on a star we can't even resolve into a
Speaker 3: picture just by measuring the time lag between the different
Speaker 3: colors of light arriving at our telescopes.
Speaker 2: That is incredible. It's like hearing a thunderclap and counting
Speaker 2: the seconds to estimate the distance of the storm. But
Speaker 2: we're doing it for stellar architecture across the galaxy.
Speaker 3: That is a perfect analogy. We are decoding the three
Speaker 3: D structure of a star from a flat one D signal.
Speaker 2: Okay, let's move to the mystery of the dimming light.
Speaker 2: Because usually when we talk about activity on the sun
Speaker 2: flares heating magnetism, we talk about things getting brighter. More
Speaker 2: energy means more light, right, but the data should something
Speaker 2: really counterintuitive in a specific wavelength.
Speaker 3: Yes, this was a real puzzle for a while. It
Speaker 3: happened specifically in the AIA one seventy one angstrom channel.
Speaker 2: Remind us again what one hundred and seventy one angstroms
Speaker 2: represents in this context.
Speaker 3: It corresponds to iron nine iron atoms that have lost
Speaker 3: eight of their electrons. This specific stay happens when the
Speaker 3: gas is at a temperature of about one million degrees kelvin.
Speaker 2: A million degrees, which, shockingly in solar physics is considered
Speaker 2: just warm.
Speaker 3: Correct, it's the warm corona. Now, you would naturally expect
Speaker 3: that when a new magnetic active region appears, it would
Speaker 3: pump energy into the gas, making it hotter and brighter
Speaker 3: in all wavelengths.
Speaker 2: Sure, you heat it up, it glows more. That's how
Speaker 2: fire works.
Speaker 3: But in the one seventy one channel, the area around
Speaker 3: the active region often gets darker. It actually dims. It
Speaker 3: creates a temporary hole in the light.
Speaker 2: Why is it cooling down Somehow is the energy disappearing?
Speaker 3: No, it's getting too hot.
Speaker 2: Too hot. How does getting hotter make something turn dark?
Speaker 3: Think of the AIA channel like a very narrow window.
Speaker 3: It is only looking for warm one million degree gas.
Speaker 3: If you take that gas and you suddenly heat it
Speaker 3: up to three million degrees, the.
Speaker 2: Iron atoms lose even more electrons.
Speaker 3: Exactly, the iron nine gets further ionized and becomes iron
Speaker 3: twelve or iron fifteen. It physically changes state, and because
Speaker 3: it's no longer iron nine, it becomes completely invisible to
Speaker 3: the one seventy one channels filter.
Speaker 2: Ah. I see, It's like a radio station. The channel
Speaker 2: is tuned exactly to one oh one point five FM.
Speaker 2: If the signal shifts up to one oh five point
Speaker 2: nine FM, the radio just goes silent.
Speaker 3: Perfect way to put it. The energy didn't disappear. It
Speaker 3: just shifted out of the passban. It graduated to a
Speaker 3: higher energy class. So when we see a sudden dimming
Speaker 3: in the warm corona, it's actually a definitive sign of
Speaker 3: intense superheating.
Speaker 2: It's a false negative, or rather a negative signal that
Speaker 2: actually proves a massive positive event exactly.
Speaker 3: And again this acts as a crucial fingerprint. If we
Speaker 3: see a distant star suddenly go dim in this specific
Speaker 3: UV band, we know it's not because the star is
Speaker 3: dying or cooling off. It's because the atmosphere is being
Speaker 3: flash heated to X ray.
Speaker 2: Temperatures, which brings us perfectly to the universal rules of heating.
Speaker 2: Because this heating question, why the atmosphere is so incredibly hot,
Speaker 2: is a huge deal in astronomy, right Yeah, I remember
Speaker 2: learning in school that the Sun's surface is about six
Speaker 2: thousand degrees, but the atmosphere above it is millions of degrees.
Speaker 3: That is the coronal heating problem. It's one of the
Speaker 3: classic enduring mysteries of astrophysics. It completely violates every day
Speaker 3: common sense. It's like walking away from a hot campfire
Speaker 3: and finding that as you get farther away, the air
Speaker 3: somehow gets hotter. And hotter.
Speaker 2: Right, if the core of the star is the heat source,
Speaker 2: it should logically get cooler as you move outward into.
Speaker 3: Space exactly, So something else must be mechanically transporting energy
Speaker 3: from the surface up into the high atmosphere and dumping
Speaker 3: it there. And the SBO data has helped us establish
Speaker 3: universal scaling laws to try and understand this process.
Speaker 2: Universal scaling laws that sounds like a commandment written in stone.
Speaker 3: It essentially is a cosmic rule book. The researchers, specifically
Speaker 3: torri Me and Airpution in their twenty twenty two paper,
Speaker 3: compared two fundamental things magnetic flux and irradiance.
Speaker 2: So measuring how much magnetism do we have on the
Speaker 2: surface versus how much light are we getting out of
Speaker 2: the atmosphere.
Speaker 3: Right, and they found a strict mathematical relationship, a power law.
Speaker 3: And the amazing thing is it holds true for our sun,
Speaker 3: but it also holds true for young stars old stars
Speaker 3: G type dwarfs, K type dwarfs. It seems to be
Speaker 3: a universal rule across the entire galaxy.
Speaker 2: Okay, let's untack the efficiency part of this law. Because
Speaker 2: the research mentions super linear and sublinear relationships. Those are
Speaker 2: dense math terms, Let's translate them for the listener.
Speaker 3: Let's use a volume knob analogy. Imagine the magnetic flux
Speaker 3: on the surface is the volume knob on your stereo receiver,
Speaker 3: and the irradiance the X ray brightness is the actual
Speaker 3: sound coming out of the speakers in your room.
Speaker 2: Okay, I follow, So if I turn the volume knob
Speaker 2: from a one to a two, do I get double sound?
Speaker 3: That entirely depends on which layer of the solar atmosphere
Speaker 3: you are listening to. If you are looking at the chromosphere,
Speaker 3: which is the lower atmosphere just above the surface, the
Speaker 3: relationship is sublinear, the.
Speaker 2: Blinear, so the slope of the graph is gentle.
Speaker 3: Right, You turn the magnetic volume knob from a one
Speaker 3: all the way to a ten, but the brightness only
Speaker 3: goes from a one to a five. It's very inefficient.
Speaker 3: You have to pump in a massive amount of magnetism
Speaker 3: to get just a little bit of extra heating.
Speaker 2: Okay, it makes sense. What about the corona then the
Speaker 2: super hot outer.
Speaker 3: Layer up there, It is super linear. The slope is
Speaker 3: incredibly steep. You turn the magnetic knob just a tiny,
Speaker 3: tiny bit, and the X ray volume, blasts out the
Speaker 3: windows and deafens you.
Speaker 2: So the corona is basically a drama queen. It severely
Speaker 2: overreacts to magnetism.
Speaker 3: That is a very scientifically accurate way to put it. Honestly,
Speaker 3: the heating mechanism in the corona is incredibly efficient. A
Speaker 3: very small increase in magnetic flux leads to a massive
Speaker 3: disproportional explosion of X ray and extreme uvlate drastic difference.
Speaker 2: Why is the chromosphere so chill and the corona is
Speaker 2: so hyper reactive.
Speaker 3: That is where the current debate lies in the field,
Speaker 3: but the scaling laws give us major clues. It strongly
Speaker 3: suggests that the actual physical mechanism of heating must change
Speaker 3: depending on the altitude. In the lower atmosphere, the thick chromosphere,
Speaker 3: it might be something called wave dissipation, like physical friction,
Speaker 3: sort of imagine violently shaking a heavy rope. The waves
Speaker 3: travel up the length of the rope. As those magnetic
Speaker 3: waves travel upward through the thick, dense lower atmosphere, they
Speaker 3: lose energy slowly through friction, heating the surrounding gas.
Speaker 2: And in the corona, it's too thin for.
Speaker 3: That, right. The corona is almost a vacuum. So in
Speaker 3: the corona. The leading theory is nanoflares, tiny explosions, billions
Speaker 3: of them, tiny completely undetectable magnetic reconnections happening constantly all
Speaker 3: over the star. Because the magnetic field is so utterly
Speaker 3: dominant up there, these tiny snaps release huge amounts of
Speaker 3: stored energy flash heating the plasma almost instantly, So.
Speaker 2: The SDO data is basically helping us figure out which
Speaker 2: heating engine is running at which specific altitude above the
Speaker 2: star exactly.
Speaker 3: And because these scaling laws are universal, we can safely
Speaker 3: assume this same process is happening on every other star
Speaker 3: out there, which allows us to do something really cool.
Speaker 3: We can essentially travel through time.
Speaker 2: Traveling through time. This is genuinely my favorite part of
Speaker 2: the research we're exploring today. Because the Sun wasn't always
Speaker 2: this calm, middle aged, respectable star we see today.
Speaker 3: No, it wasn't. The Sun used to be a teenager,
Speaker 3: and like many teenagers, it was wild, highly energetic, and
Speaker 3: frankly a little dangerous to be around.
Speaker 2: Stellar evolution is fascinating. Remind us how a typical star ages.
Speaker 3: When stars exactly like our Sun are first born, they
Speaker 3: spin very, very fast, they can serve the angular momentum
Speaker 3: from the giant collapsing gas cloud they formed from.
Speaker 2: Just like an ice skater pulling their arms into spin faster, exactly.
Speaker 3: The same physics. And because they spin so fast, they're
Speaker 3: internal dynamo, the swirling engine of li. When plasma that
Speaker 3: creates the magnetic field works an absolute overdrive, fast spin
Speaker 3: equals massive chaotic magnetism.
Speaker 2: So young Sun is just a magnetic monster.
Speaker 3: An absolute monster. It would have been covered in giant
Speaker 3: star spots blasting out terrifying superflares every other day. But
Speaker 3: as stars age, they naturally slow down. They lose angular
Speaker 3: momentum constantly through their solar wind blowing out into space.
Speaker 3: It acts like a slow magnetic break.
Speaker 2: This process is called Schumanic slaw. Right.
Speaker 3: Yes, the older stargats, the slower it spins, and the
Speaker 3: magnetically quieter it becomes. Our Sun is currently about four
Speaker 3: point six billion years old. It rotates once a month.
Speaker 3: It's firmly in its quiet, settling down phase.
Speaker 2: What astronomers want to know what the Sun was like
Speaker 2: four billion years ago, right when life was just starting
Speaker 2: to form on Earth. Obviously, we can't build a time
Speaker 2: machine go back.
Speaker 3: We can't. But thanks to these universal scaling laws we
Speaker 3: just talked about, we can look at other stars out
Speaker 3: in the galaxy that are exactly like the Sun, but
Speaker 3: younger the young suns precisely. For example, we look at
Speaker 3: a star called Ekdraponas it has the exact same mass
Speaker 3: as our Sun, the same chemical composition, but it's only
Speaker 3: one hundred million years old. On a cosmic scale, it's
Speaker 3: an infant, so it spins much much faster.
Speaker 2: And because we know the scaling laws work universally across
Speaker 2: all these stars, we can apply the rules we learned
Speaker 2: from staring at our own Sun with sdo directly to
Speaker 2: ek Draconis.
Speaker 3: Yes, we measure Ekdraconus's magnetic flux, we plug that number
Speaker 3: into the mathematical equation we derive from our Sun, and
Speaker 3: we can accurately model its entire atmosphere. We verified that
Speaker 3: the physics is exactly the same. The same equations that
Speaker 3: describe a small, everyday solar flare on our son today
Speaker 3: perfectly described the massive apocalyptic superflares happening on Ekdraconas that
Speaker 3: is profound.
Speaker 2: So by pointing our telescopes at a star one hundred
Speaker 2: light years away, we're actually looking into a mirror reflecting
Speaker 2: our own solar systems past.
Speaker 3: We are seeing the exact harsh environment that the early
Speaker 3: Earth grew up in, and let me tell you, it
Speaker 3: was a very violent neighborhood. The young Sun was relentlessly
Speaker 3: blasting the early Earth with X rays and UV radiation
Speaker 3: at levels hundreds or even thousands of times higher than
Speaker 3: what we experienced today.
Speaker 2: It's a miracle life survived at all under that bombardment,
Speaker 2: which brings us to the real stakes of all this research.
Speaker 2: It's not just about historical curiosity. It's about the search
Speaker 2: for life right now in the galaxy, the invisible danger
Speaker 2: to exoplanets.
Speaker 3: This is where the rubber really meets the road. From
Speaker 3: modern astronomy. We are finding thousands of planets orbiting other stars, exoplanets,
Speaker 3: and the ultimate holy grail of astronomy right now is
Speaker 3: to find a planet that is truly.
Speaker 2: Habitable an Earth two point zero, right.
Speaker 3: But to know if a rocky planet is habitable, you
Speaker 3: need to know if it has an atmosphere. You can
Speaker 3: be at the perfect distance from the Goldilocks zone for
Speaker 3: liquid water, but if you don't have an air blanket,
Speaker 3: you're just a barren freezing rock.
Speaker 2: And the biggest enemy of a planetary atmosphere is the
Speaker 2: host star.
Speaker 3: Itself, specifically the star's extreme ultraviolet or EUV radiation.
Speaker 2: Why is EUV the main villain here? What does it do?
Speaker 3: EUV photons carry a massive amount of energy. When they
Speaker 3: hit the upper atmosphere of a planet, they violently heat
Speaker 3: up the gas. If they heat it up enough, the
Speaker 3: gas molecules start moving so fast they actually reach escape
Speaker 3: velocity and break free of the planet's gravity. They literally
Speaker 3: boil away into deep space.
Speaker 2: This is exactly what happened to Mars, isn't it largely?
Speaker 3: Yes, Mars' is core cooled, it lost its protective magnetic shield,
Speaker 3: and then the solar wind and the Sun's EUV radiation
Speaker 3: slowly stripped its thick atmosphere away over billions of years.
Speaker 3: So if we want to know if a distant exoplanet
Speaker 3: has air to breathe, we need to know exactly how
Speaker 3: much EUV its host star is hitting it with.
Speaker 2: Okay, so that seems straightforward. Let's just point our telescopes
Speaker 2: at the star and measure the EV output we can.
Speaker 2: Why not we have the James Webb space telescope. We
Speaker 2: have hubble. We have the best tech in history.
Speaker 3: It's what we call the observation barrier. The vast space
Speaker 3: between stars isn't actually empty. It's filled with the interstellar medium,
Speaker 3: a very thin, sprawling fog of hydrogen and helium gas.
Speaker 2: And hydrogen loves to absorb ultraviolet light.
Speaker 3: It absolutely eats it. It absorbs it completely. From our
Speaker 3: vantage point here on Earth, the EUV signal of distant
Speaker 3: stars is totally invisible. It gets entirely blocked by the
Speaker 3: interstellar fog before it ever reaches our telescopes. We are
Speaker 3: completely blind to the very thing that determines habitability.
Speaker 2: That sounds like a frustrating dead end for astronomers. We
Speaker 2: desperately need the data, but the universe is physically hiding
Speaker 2: it from us.
Speaker 3: It was a dead end for a long time until researchers,
Speaker 3: specifically Namakata and his team in a recent paper, figured
Speaker 3: out how to utilize the solar scaling laws to bypass
Speaker 3: the fog.
Speaker 2: Entirely, using the Rosetta stone.
Speaker 3: Again, exactly here is the brilliant trick. We cannot see
Speaker 3: the EUV light coming from the star, but we can
Speaker 3: see other things. Specifically, we can easily see the calcium
Speaker 3: taka k line calcium like in milk, same element. Yes,
Speaker 3: it's a very specific wavelength of violet light emitted by
Speaker 3: ionized calcium atoms glowing in the star's lower atmosphere. And crucially,
Speaker 3: the interstellar medium does not block calcium light. It punches
Speaker 3: right through the fog and reaches our telescopes loud and clear.
Speaker 2: Okay, so we can perfectly measure the calcium output of
Speaker 2: a distant star right now.
Speaker 3: We turn back to our Rosetta stone. We look at
Speaker 3: a decade of SDO data for our own Sun, and
Speaker 3: we ask a simple question. Hey, Historically, every time the
Speaker 3: Sun emitted this specific amount of calcium light, exactly how
Speaker 3: much EUV was it spitting out at the exact same time.
Speaker 2: We find the mathematical correlation between the two.
Speaker 3: We build a highly accurate calibration curve. We find that
Speaker 3: calcium emissions and EUV emissions are tightly predictably linked. If
Speaker 3: the calcium signal goes up, the EUV signal goes up
Speaker 3: by a knowable amount.
Speaker 2: So we use our sun to create a universal conversion formula.
Speaker 3: Exactly, we cheat the system. We take the visible calcium
Speaker 3: measurement from the star which we can easily see. We
Speaker 3: plug it into the solar equation we derive, and we
Speaker 3: mathematically reconstruct the entirely invisible EUV spectrum.
Speaker 2: We fill in the blank. We basically reconstruct the crime scene.
Speaker 2: Using proxy evidence.
Speaker 3: We can effectively say with high confidence, based on this
Speaker 3: star's calcium signal today, it must be emitting exactly this
Speaker 3: much ev radiation right now, and that.
Speaker 2: Final number tells us if the planet orbiting it is
Speaker 2: a nice lush place to visit or just a radiated,
Speaker 2: airless rock exactly.
Speaker 3: This breakthrough allows us to realistically model the atmospheres of
Speaker 3: Earth like planets around other stars for the first time.
Speaker 3: We can predict if a planet has been completely stripped
Speaker 3: bare over a billion years, or if it might still
Speaker 3: have oceans of water and breathable air. All of it
Speaker 3: is based on math derived directly from staring at our
Speaker 3: own sun.
Speaker 2: That perfectly connects everything we've talked about. We started with
Speaker 2: a camera just looking at our local sun, and we
Speaker 2: ended up predicting the weather on alien worlds trillions of
Speaker 2: miles away.
Speaker 3: That is the true power of the soul or stellar connection.
Speaker 3: You simply cannot understand the distant universe without first deeply
Speaker 3: understanding the local one.
Speaker 2: So let's wrap this up. We have covered a massive
Speaker 2: amount of ground today.
Speaker 3: We really have. It's been quite a journey from the
Speaker 3: very surface of the Sun all the way to the
Speaker 3: edge of the galaxy.
Speaker 2: We started with the STO, the Ultimate Solar camera. We
Speaker 2: learned that it's not just taking pretty pictures, it's physically
Speaker 2: mapping invisible magnetism with HMI and peeling back the thermal
Speaker 2: onion of the atmosphere using AIA.
Speaker 3: We discussed how clever scientists downgrade that gorgeous HD data
Speaker 3: to sun as a star data, creating a functional dictionary
Speaker 3: to translate the blurry pixelated signals of distant stars.
Speaker 2: We solve the mystery of the faculae, discovering why stars
Speaker 2: look brighter when sunspots are near the edge because of
Speaker 2: that crazy hot wall effect.
Speaker 3: We looked at the rotating skyscraper analogy, using time lags
Speaker 3: between UV and visible light to physically measure the three
Speaker 3: D height of magnetic loops that are light years away
Speaker 3: from us, and we explained why a sudden dimming in
Speaker 3: the corona is actually a terrifying sign of extreme superheating.
Speaker 2: We walk through the universal scaling laws using the volume
Speaker 2: knob analogy, how the corona is super linear and highly
Speaker 2: efficient at heating, while the lower chromosphere is sublinear and stubborn.
Speaker 3: And finally we saw how that intricate math lets us
Speaker 3: see the completely invisible using calcium proxies to reconstruct the
Speaker 3: deadly euv radiation that ultimately dictates the fate of every
Speaker 3: exoplanet out there.
Speaker 2: It really firmly validates the idea of the Sun as
Speaker 2: a cosmic Rosetta stone.
Speaker 3: It really does. It kind of changes your whole philosophy
Speaker 3: a bit. When you look up. The Sun is so
Speaker 3: much more than just our life giver. It is our translator.
Speaker 3: Without the Sun acting as our baseline, the rest of
Speaker 3: the universe would be a dark, completely confusing place. We
Speaker 3: would see all those little points of light in the
Speaker 3: night sky, but we wouldn't understand a single word of
Speaker 3: the language they are speaking. The Sun teaches us the
Speaker 3: fundamental grammar of the cosmos.
Speaker 2: That's a beautiful way to put it. We are incredibly
Speaker 2: lucky to have such a detailed, accessible textbook right.
Speaker 3: Next door we are. And here is a final thought
Speaker 3: I want to leave you with today.
Speaker 2: Let's hear it.
Speaker 3: We constantly call other stars sunlike. Astronomers use that term
Speaker 3: all the time. We look for sun like stars, specifically
Speaker 3: to find Earth like planets. But as we discussed today,
Speaker 3: even our own sun hasn't always been sunlike. It was
Speaker 3: once a raging monster, and billions of years from now
Speaker 3: it will eventually swell into a massive red giant. When
Speaker 3: we look at the night sky, we aren't just looking
Speaker 3: at a random collection of different objects. We are actually
Speaker 3: looking at a sprawling photo album of our own life.
Speaker 2: A timeline of our own existence.
Speaker 3: Exactly, every star out there is a snapshot of our
Speaker 3: own distant past or our inevitable future. By studying violent,
Speaker 3: young stars like e. K. Draconis, we vividly see our
Speaker 3: own birth. By studying old, dying stars, we clearly see
Speaker 3: our own end. We are really just studying ourselves.
Speaker 2: Man, that is deep. I'm going to be thinking about
Speaker 2: that next time I put on a pair of sunglasses.
Speaker 2: I'm not just blocking the glare. I'm blocking out the
Speaker 2: deepest secrets of the universe.
Speaker 3: Well, maybe let a little bit of the secret in
Speaker 3: from time to time. Just please don't stare directly at it.
Speaker 2: Sound advice. Thank you all for joining us on this
Speaker 2: exploration into the Rosetta Stone Star.
Speaker 3: Keep looking up and keep asking questions.
Speaker 2: The next time Sai