WEBVTT 1 00:00:03.439 --> 00:00:07.719 Welcome to Bedtime Astronomy. Explore the wonders of the cosmos 2 00:00:07.759 --> 00:00:12.279 with our soothing Bedtime Astronomie podcast. Each episode offers a 3 00:00:12.359 --> 00:00:16.320 gentle journey through the stars, planets, and beyond, perfect for 4 00:00:16.399 --> 00:00:20.239 unwinding after a long day. Let's travel through the mysteries 5 00:00:20.239 --> 00:00:22.440 of the universe as you drift off into a peaceful 6 00:00:22.480 --> 00:00:23.839 slumber under the night sky. 7 00:00:26.879 --> 00:00:30.359 I want you to take a second and just imagine 8 00:00:30.399 --> 00:00:33.359 looking through a viewing portal, but you're not looking at 9 00:00:33.399 --> 00:00:36.159 the universe as it is today. You are watching a 10 00:00:36.240 --> 00:00:39.840 mirror image of our very own solar system, but at 11 00:00:39.880 --> 00:00:45.240 the exact moment of its like chaotic, violent birth. You're 12 00:00:45.280 --> 00:00:48.679 not seeing Earth and Mars and Jupiter all neatly sorted 13 00:00:48.679 --> 00:00:52.799 into their stable orbits. You were watching this swirling, turbulent 14 00:00:52.920 --> 00:00:56.560 delivery room of a cosmic neighborhood. And the craziest part 15 00:00:56.679 --> 00:00:59.960 is you are watching it actively unfold right this second. 16 00:01:00.520 --> 00:01:03.600 Yeah, and for the vast majority of astronomical history, trying 17 00:01:03.640 --> 00:01:08.719 to understand how planets formed was basically an exercise in forensics, right, 18 00:01:08.840 --> 00:01:10.959 like a crime scene exactly. I mean, we had our 19 00:01:10.959 --> 00:01:13.359 own mature solar system to study, and we were essentially 20 00:01:13.359 --> 00:01:15.599 just investigating the aftermath of a massive. 21 00:01:15.319 --> 00:01:17.120 Explosion, just looking at the debris. 22 00:01:17.239 --> 00:01:20.120 Right, we had to look at this coal debris, you know, 23 00:01:20.200 --> 00:01:23.079 the current orbits of the planets, the makeup of asteroids, 24 00:01:23.079 --> 00:01:25.920 where the comets are distributed. And from that we had 25 00:01:25.920 --> 00:01:29.560 to try and reverse engineer the exact placement and like 26 00:01:29.840 --> 00:01:32.480 the yield of the original dynamite. 27 00:01:32.040 --> 00:01:34.560 Which sounds impossible, it's incredibly difficult. 28 00:01:34.599 --> 00:01:38.120 I mean, we had theoretical physics models running on supercomputers, sure, 29 00:01:38.519 --> 00:01:41.719 but we lacked the direct observational evidence of the process 30 00:01:41.760 --> 00:01:45.879 actually occurring. But now, well, the paradigm has completely shifted. 31 00:01:46.040 --> 00:01:49.200 What's fascinating here is we are transitioning from guessing how 32 00:01:49.239 --> 00:01:53.159 planets form to actively watching it happen. We basically have 33 00:01:53.280 --> 00:01:55.319 a camera recording the blast. 34 00:01:55.480 --> 00:01:59.000 Okay, let's unpack this, because that shift is exactly what 35 00:01:59.079 --> 00:02:01.680 makes late more Arch of twenty twenty six such a 36 00:02:01.799 --> 00:02:03.319 landmark moment for astronomy. 37 00:02:03.359 --> 00:02:03.519 Oh. 38 00:02:03.519 --> 00:02:07.599 Absolutely, Telescopes pointed at the constellation Aquila, which is about 39 00:02:08.240 --> 00:02:11.199 four hundred and thirty seven light years away, have captured 40 00:02:11.199 --> 00:02:14.560 the most detailed, structurally complex view we have ever seen 41 00:02:14.639 --> 00:02:16.919 of a new solar system forming. It's stune in and 42 00:02:16.960 --> 00:02:19.360 the anchor of this whole system is a baby star. 43 00:02:19.479 --> 00:02:22.560 They needed it, whisp it too, right, And surrounding it 44 00:02:22.639 --> 00:02:26.319 is this colossal disk of gas and dust. Embedded in 45 00:02:26.360 --> 00:02:30.039 that disk are two confirmed heavyweight planets, and they are 46 00:02:30.080 --> 00:02:32.960 actively gorging on material and carving out their orbits, which. 47 00:02:32.840 --> 00:02:35.039 Is just wild to see in real time, it really is. 48 00:02:35.639 --> 00:02:39.120 So our objective today is to explore exactly how those 49 00:02:39.199 --> 00:02:43.560 chaotic clouds of dust actually transform into structured worlds. We're 50 00:02:43.560 --> 00:02:45.919 going to look at what these newly discovered giant baby 51 00:02:45.960 --> 00:02:48.919 planets look like, and how this five million year old 52 00:02:48.960 --> 00:02:52.599 star holds the secrets to our own four point six 53 00:02:52.719 --> 00:02:53.759 billion year history. 54 00:02:53.960 --> 00:02:58.560 Yeah, the transition from theoretical modeling to direct observation, it 55 00:02:58.599 --> 00:03:00.360 really just cannot be overset. 56 00:03:00.319 --> 00:03:02.960 Here because it used to just be math on a chalkboard. 57 00:03:02.599 --> 00:03:08.000 Exactly for decades. The intricate mechanisms of planetary accretion. You know, 58 00:03:08.080 --> 00:03:12.319 how microscopic dust grains overcome electrostatic barriers, how they stick 59 00:03:12.319 --> 00:03:15.360 together to grow into pebbles and then planetesimals and eventually 60 00:03:15.400 --> 00:03:18.599 into massive gas giants. All of that mostly lived in 61 00:03:18.680 --> 00:03:23.960 fluid dynamics equations and magnetohydrodynamic simulation, which is a mouthful, 62 00:03:24.039 --> 00:03:26.319 it is, but basically we knew the math worked. The 63 00:03:26.360 --> 00:03:29.479 problem was ground shooth verification was really scarce. 64 00:03:29.560 --> 00:03:31.680 We could just go out and take a picture of it, right. 65 00:03:31.840 --> 00:03:35.199 But whisp It two offers us this multiplanet laboratory where 66 00:03:35.199 --> 00:03:38.400 we can finally test those models against reality. We can 67 00:03:38.439 --> 00:03:42.599 measure the exact mass, the temperature, the orbital kinematics of 68 00:03:42.639 --> 00:03:45.039 these planets as they are actively being forged. 69 00:03:45.159 --> 00:03:47.159 Okay, so let's start with the anchor of the whole thing, 70 00:03:47.240 --> 00:03:50.719 the star itself, whisp It too. Okay, it's characterized as 71 00:03:50.759 --> 00:03:54.159 a pre main sequence star and it's roughly five million 72 00:03:54.240 --> 00:03:57.280 years old. Now to you and me, five million years 73 00:03:57.319 --> 00:04:00.319 sounds ancient, right sure, But against the four point six 74 00:04:00.319 --> 00:04:02.680 billion year age of our own Sun, whisp of two 75 00:04:02.759 --> 00:04:06.120 is basically a newborn, very much so. But the metric 76 00:04:06.159 --> 00:04:08.719 that really caught my eyes it's mass. It's clocked at 77 00:04:08.719 --> 00:04:10.360 one point zero eight solar masses. 78 00:04:10.599 --> 00:04:12.280 Yeah, that's the crucial number. 79 00:04:12.120 --> 00:04:14.319 Because it makes it a near perfect analog for what 80 00:04:14.400 --> 00:04:16.199 our Sun looked like when it was a baby. It's 81 00:04:16.279 --> 00:04:17.560 essentially a twin exactly. 82 00:04:17.600 --> 00:04:20.240 It's that one point arrow eight solar mass metric. That 83 00:04:20.319 --> 00:04:24.000 makes it so valuable because its composition and size mirror 84 00:04:24.040 --> 00:04:28.399 our Sun. The surrounding protoplanetary disk that's swirling reservoir of 85 00:04:28.480 --> 00:04:31.399 leftover gas and dust is the perfect proxy for the 86 00:04:31.399 --> 00:04:33.040 primordial soup that build Earth. 87 00:04:33.120 --> 00:04:35.560 Right, But you mentioned it's a pre main sequence star, 88 00:04:35.879 --> 00:04:37.360 meaning it hasn't turned on yet. 89 00:04:37.639 --> 00:04:41.680 Basically, yes, it hasn't achieved the internal pressure and temperature 90 00:04:41.759 --> 00:04:44.800 required to ignite sustained hydrogen fusion in its core. 91 00:04:45.360 --> 00:04:47.639 So if wisp it iiO hasn't turned on as core 92 00:04:47.720 --> 00:04:51.319 hydrogen fusion yet, where's the thermal budget coming from? Like 93 00:04:51.680 --> 00:04:54.519 is the surrounding material colder or is the violence of 94 00:04:54.560 --> 00:04:57.800 gravity providing the heat? How is it generating enough energy 95 00:04:57.839 --> 00:04:59.920 to keep the disc from just freezing into solid ice? 96 00:05:00.480 --> 00:05:02.560 That is a great question, and it goes straight to 97 00:05:02.600 --> 00:05:05.759 the thermodynamics of how stars are born. Okay, while wispit 98 00:05:05.839 --> 00:05:09.720 two lacks that sustained hydrogen fusion, it's driven by something 99 00:05:09.759 --> 00:05:11.759 we call the Kelvin Helmholtz mechanism. 100 00:05:11.959 --> 00:05:14.519 The Kelvin Helmholtz mechanism, got it, What is that? 101 00:05:14.839 --> 00:05:17.920 So the star is still in the process of gravitational collapse. 102 00:05:18.319 --> 00:05:22.160 It formed from a vast cold molecular cloud, and as 103 00:05:22.240 --> 00:05:25.759 that immense volume of gas falls inward on itself, gravitational 104 00:05:25.800 --> 00:05:28.319 potential energy gets converted into kinetic. 105 00:05:28.040 --> 00:05:30.240 Energy because it's moving faster, exactly. 106 00:05:30.319 --> 00:05:33.120 And as those gas particles compress and collide at higher 107 00:05:33.160 --> 00:05:37.360 and higher velocities, that kinetic energy is converted into thermal energy. 108 00:05:37.480 --> 00:05:40.040 So it's essentially heating up because it's crushing itself. 109 00:05:40.279 --> 00:05:43.360 That is exactly the mechanism. It's glowing purely from the 110 00:05:43.399 --> 00:05:46.639 intense friction and pressure of its own gravitational contraction. 111 00:05:46.879 --> 00:05:47.199 Wow. 112 00:05:47.800 --> 00:05:50.759 Yeah, And according to the viurial theorem, about half of 113 00:05:50.839 --> 00:05:55.000 the gravitational potential energy released during this collapse radiates away 114 00:05:55.000 --> 00:05:58.199 as starlight and the other half remains trapped inside and 115 00:05:58.240 --> 00:06:02.800 it steadily raises the coret temperature. Eventually, millions of years 116 00:06:02.800 --> 00:06:07.240 from now, that core temperature will hit roughly fifteen million. 117 00:06:06.920 --> 00:06:09.079 Kelvin, which is when it finally turns on. 118 00:06:09.319 --> 00:06:12.920 Right, that's what's required to sustain hydrogen fusion, and whisp 119 00:06:12.959 --> 00:06:16.639 bit two will officially join the main sequence. But right now, 120 00:06:16.680 --> 00:06:19.639 the fact that it hasn't ignited fusion is huge. 121 00:06:19.720 --> 00:06:21.279 Why is that so important for the planets? 122 00:06:21.560 --> 00:06:26.600 Because it hasn't generated the intense sustained stellar winds yet 123 00:06:27.160 --> 00:06:30.800 that outward radiation pressure that eventually blows all the primordial 124 00:06:31.160 --> 00:06:34.000 planet making material out of the system. Oh I see, Yeah, 125 00:06:34.199 --> 00:06:37.800 So the protoplanetary disk around wispit two is still dense, 126 00:06:37.920 --> 00:06:40.759 it's rich, and it's undisturbed, so. 127 00:06:40.680 --> 00:06:43.600 It's prime real estate for building planets exactly. Now. I 128 00:06:43.639 --> 00:06:45.759 know this isn't the absolute first time we've caught a 129 00:06:45.759 --> 00:06:49.040 system in this phase. Back in twenty eighteen, there was 130 00:06:49.079 --> 00:06:50.720 the discovery of PDS. 131 00:06:50.240 --> 00:06:52.639 Seventy, Yes, a very famous system. 132 00:06:52.519 --> 00:06:54.639 Right, it's about three hundred and seventy light years away, 133 00:06:54.879 --> 00:06:58.240 and astronomers found two forming protoplanets there. That was the 134 00:06:58.240 --> 00:07:01.560 first proof that we could actually witness planetary birth. But 135 00:07:01.600 --> 00:07:04.199 when I was looking into this, it seems like PDS 136 00:07:04.199 --> 00:07:07.279 seventy is treated as a proof of concept, whereas wispit 137 00:07:07.279 --> 00:07:10.519 two is being treated as this comprehensive laboratory. 138 00:07:10.759 --> 00:07:12.000 That's a very fair assessment. 139 00:07:12.120 --> 00:07:14.639 I kind of think of PDS seventy as like finding 140 00:07:14.680 --> 00:07:18.399 a single blurry polaroid of a baby, huh, whereas whispit 141 00:07:18.399 --> 00:07:21.079 two is like finding an entire high definition home video 142 00:07:21.360 --> 00:07:24.839 with a wider cast of characters. But what specific data 143 00:07:24.839 --> 00:07:28.319 does whispit two provide that fundamentally elevates our understanding compared 144 00:07:28.319 --> 00:07:29.199 to PDS seventy. 145 00:07:29.399 --> 00:07:32.160 Well, PDS seventy was a watershed moment for sure. It 146 00:07:32.199 --> 00:07:36.360 gave us the first unambiguous direct images of protoplanets PDS 147 00:07:36.360 --> 00:07:39.199 seventy B and C sitting inside a transition disc. Right, 148 00:07:39.279 --> 00:07:42.519 we could measure their hydrogen alpha emission, which is basically 149 00:07:42.600 --> 00:07:45.040 a specific wavelength of light that acts as a direct 150 00:07:45.120 --> 00:07:48.360 tracer of hot hydrogen gas accreting onto the planets. 151 00:07:48.480 --> 00:07:50.920 So it proved that planets were actually gathering material. 152 00:07:51.240 --> 00:07:55.519 Yes, it proved the accretion models were fundamentally correct. However, 153 00:07:56.040 --> 00:07:59.480 PDS seventy had limitations when it came to visibility of 154 00:07:59.519 --> 00:08:01.160 the discs structure itself, like. 155 00:08:01.160 --> 00:08:02.560 The environment around the planets. 156 00:08:02.680 --> 00:08:07.720 Exactly the gaps were there, but the extended complex architecture 157 00:08:07.879 --> 00:08:09.600 wasn't as cleanly defined. 158 00:08:09.279 --> 00:08:11.720 So it was essentially just a narrow window into the process. 159 00:08:11.800 --> 00:08:17.240 Yes, whispit two, by contrast, has an extraordinarily extended disc. 160 00:08:17.839 --> 00:08:22.720 It has multiple highly distinct concentric rings and these deeply 161 00:08:22.759 --> 00:08:26.439 carved gaps that are clean enough to measure precise kinematic. 162 00:08:26.040 --> 00:08:28.720 Deviations, meaning we can see how things are moving. 163 00:08:28.759 --> 00:08:31.480 We aren't just seeing the planets glowing. We can measure 164 00:08:31.519 --> 00:08:34.399 the exact velocity field of the gas flowing around them. 165 00:08:34.639 --> 00:08:37.919 We can map the surface density gradients of the dust. Wow, 166 00:08:38.080 --> 00:08:40.919 Whispit too allows us to observe not just the existence 167 00:08:40.960 --> 00:08:43.720 of the planets, but the real time fluid dynamics of 168 00:08:43.759 --> 00:08:45.320 the environment they are manipulating. 169 00:08:45.679 --> 00:08:48.039 Okay, so let's talk about the planets too in the manipulating, 170 00:08:48.480 --> 00:08:51.679 because the scale of these bodies is just staggering. 171 00:08:51.799 --> 00:08:53.080 They are massive, right. 172 00:08:53.600 --> 00:08:56.919 The first one confirmed, Whispit two B, was directly imaged 173 00:08:56.919 --> 00:09:00.639 in twenty twenty five. This is a gas giant with 174 00:09:00.720 --> 00:09:03.559 a mass roughly four point nine times that of Jupiter, 175 00:09:04.200 --> 00:09:06.679 and its orbital location is way out in the deep 176 00:09:06.720 --> 00:09:08.919 frieze of the system. It's sitting at a distance of 177 00:09:09.000 --> 00:09:12.120 fifty seven to sixty astronomical units from the host star. 178 00:09:12.879 --> 00:09:15.960 And for context for you listening, Neptune sits at thirty AU. 179 00:09:16.519 --> 00:09:18.879 So Whispit two B is orbiting at twice the distance 180 00:09:18.919 --> 00:09:21.240 of the furthest major planet in our own Solar system. 181 00:09:21.360 --> 00:09:23.879 Yeah, and a four point nine juper mass object at 182 00:09:23.919 --> 00:09:28.480 sixty AU poses a significant challenge to our standard formation models, 183 00:09:28.759 --> 00:09:30.240 which we can get into later. 184 00:09:30.399 --> 00:09:32.320 Right, but physically what is it doing out there? 185 00:09:32.360 --> 00:09:34.840 Well, regarding its physical state, Whispit two B is currently 186 00:09:34.840 --> 00:09:38.399 operating as a massive gravitational sink. Okay, at sixty AU. 187 00:09:38.519 --> 00:09:41.919 The orbital period is vast, meaning the planet takes hundreds 188 00:09:41.960 --> 00:09:44.480 of years to complete a single revolution around the star. 189 00:09:44.679 --> 00:09:47.320 Just one year for that planet is centuries for us exactly. 190 00:09:47.360 --> 00:09:49.679 And as it slowly plows through the outer disc, it 191 00:09:49.759 --> 00:09:52.039 is accreting gas and dust within its hill sphere. 192 00:09:52.080 --> 00:09:52.759 It's hillsphere. 193 00:09:52.840 --> 00:09:55.679 Yeah, the hill sphere is the region where the planet's 194 00:09:55.679 --> 00:09:59.320 gravity dominates over the gravitational pull of the host star. 195 00:09:59.559 --> 00:10:03.639 Oh so anything that enters that sphere is basically getting 196 00:10:03.639 --> 00:10:06.799 sucked in pretty much. And that accretion process itself is 197 00:10:06.840 --> 00:10:10.320 generating a massive amount of in red radiation. Correct, Yeah, 198 00:10:10.320 --> 00:10:11.960 I mean the heat isn't just coming from the star, 199 00:10:12.039 --> 00:10:15.919 It's coming from these colossal, glowing babies hidden in the dust. 200 00:10:16.320 --> 00:10:19.519 The material isn't just gently falling onto the planet, it's 201 00:10:19.559 --> 00:10:20.559 slamming into it. 202 00:10:20.840 --> 00:10:24.080 Yes, the physics of accretion are incredibly violent. 203 00:10:24.200 --> 00:10:26.080 How violent are we talking? Well? 204 00:10:26.320 --> 00:10:29.840 Gas falling toward the planet accelerates to supersonic speeds. 205 00:10:30.000 --> 00:10:30.360 Wow. 206 00:10:30.440 --> 00:10:33.360 And when it finally strikes the denser atmosphere or the 207 00:10:33.399 --> 00:10:37.240 surface of the growing proto planet, it creates an accretion shock. 208 00:10:37.480 --> 00:10:38.039 Oh man. 209 00:10:38.240 --> 00:10:41.960 The kinetic energy of that in falling gas is instantaneously 210 00:10:42.039 --> 00:10:46.600 converted into heat. It raises the local temperature to thousands. 211 00:10:46.120 --> 00:10:48.559 Of degrees, So even out in the deep freeze, it's 212 00:10:48.600 --> 00:10:49.320 scorching hot. 213 00:10:49.559 --> 00:10:53.000 Exactly. That is why a planet out at sixty AU, 214 00:10:53.440 --> 00:10:55.799 a region where the ambient temperature of the disk is 215 00:10:55.799 --> 00:10:59.639 barely above absolute zero, is glowing brightly enough in the 216 00:10:59.639 --> 00:11:02.039 near for red spectrum to be detected four hundred and 217 00:11:02.039 --> 00:11:03.759 thirty seven light years away, because. 218 00:11:03.559 --> 00:11:06.320 It's radiating its own formation. Here. Yes, okay, so that's 219 00:11:06.360 --> 00:11:08.399 the outer planet. But that brings us to the March 220 00:11:08.480 --> 00:11:12.240 twenty twenty six data which confirmed the second planet Wispit 221 00:11:12.240 --> 00:11:15.159 to C. And here is where it gets really interesting. 222 00:11:15.639 --> 00:11:19.080 The architecture of this system becomes highly counterintuitive. It does 223 00:11:19.200 --> 00:11:22.679 Whispit two c orbits much closer to the star at 224 00:11:22.759 --> 00:11:26.320 roughly fourteen AU, yet it is estimated to be between 225 00:11:26.320 --> 00:11:29.679 eight and twelve jupiter masses. It is roughly twice as 226 00:11:29.679 --> 00:11:30.720 massive as the outer planet. 227 00:11:30.879 --> 00:11:31.679 Yes, it's a heavyweight. 228 00:11:31.960 --> 00:11:36.279 But confirming this required spectroscopic data, specifically looking for carbon monoxide, 229 00:11:36.480 --> 00:11:39.360 walking through the physics of that detection. Because finding something 230 00:11:39.399 --> 00:11:42.039 at fourteen AU seems way harder than finding something at 231 00:11:42.039 --> 00:11:42.679 sixty AU. 232 00:11:42.919 --> 00:11:46.360 It is significantly harder. Confirming wispit two C was a 233 00:11:46.480 --> 00:11:49.039 huge triumph of high resolution spectroscopy. 234 00:11:49.080 --> 00:11:50.679 Why is it so difficult. 235 00:11:50.159 --> 00:11:54.240 Because at fourteen au the angular separation between the planet 236 00:11:54.279 --> 00:11:57.440 and the star is incredibly tight. The glare of WISPIT 237 00:11:57.519 --> 00:11:58.879 two is overwhelming. 238 00:11:59.039 --> 00:12:00.840 It's just blinding that telescope, right. 239 00:12:01.000 --> 00:12:03.559 So to prove that this faint point of light wasn't 240 00:12:03.600 --> 00:12:06.440 just a background artifact or like a localized clump of 241 00:12:06.480 --> 00:12:12.000 hot dust, astronomers utilized integral field spectrographs. Okay, they needed 242 00:12:12.000 --> 00:12:15.720 to analyze the specific wavelengths of light being emitted. They 243 00:12:15.799 --> 00:12:19.480 targeted the K band in the near infrared, and specifically 244 00:12:19.559 --> 00:12:22.320 they were looking for the row vibrational absorption bands of 245 00:12:22.360 --> 00:12:26.159 carbon monoxide, which occur around two point three microns. 246 00:12:26.279 --> 00:12:28.879 Wait, why carbon monoxide that? Why not look for hydrogen 247 00:12:29.039 --> 00:12:29.600 or methane. 248 00:12:29.600 --> 00:12:32.960 That's a good point. So carbon monoxide is an exceptionally 249 00:12:33.039 --> 00:12:36.639 stable molecule and it's a dominant carbon bearing species in 250 00:12:36.720 --> 00:12:40.360 the hot, high pressure environments of forming gas giant atmospheres. 251 00:12:40.440 --> 00:12:42.399 Oh okay, so it survives the heat exactly. 252 00:12:42.759 --> 00:12:45.519 Methane, on the other hand, requires much cooler temperatures to 253 00:12:45.559 --> 00:12:49.480 remain stable in large quantities and hydrogen. Hydrogen is abundant, sure, 254 00:12:49.960 --> 00:12:53.000 but its emission lines can often be confused with stellar 255 00:12:53.039 --> 00:12:56.240 activity or just general accretion flows in the broader disk. 256 00:12:56.639 --> 00:12:58.039 So it's not specific. 257 00:12:57.679 --> 00:13:01.000 Enough, right, But the specific roe Vibe rational signature of 258 00:13:01.080 --> 00:13:06.000 carbon monoxide acts as an unequivocal chemical fingerprint for a 259 00:13:06.120 --> 00:13:08.519 dense planetary mass atmosphere. 260 00:13:08.679 --> 00:13:12.679 It's the smoking gun exactly. But finding the molecule isn't 261 00:13:12.759 --> 00:13:14.600 enough on its own, is it. I mean you have 262 00:13:14.639 --> 00:13:17.360 to prove it actually belongs to something orbiting the star 263 00:13:17.720 --> 00:13:19.759 and not just gas floating around. 264 00:13:19.960 --> 00:13:22.600 Yes, and that is where the kinematics come into play 265 00:13:22.720 --> 00:13:25.919 the movement right By observing the K band spectrum with 266 00:13:26.120 --> 00:13:30.799 incredibly high spectral resolution, astronomers can measure the Doppler shift 267 00:13:30.879 --> 00:13:32.759 of those carbon monoxide. 268 00:13:32.200 --> 00:13:34.639 Lines, like how a siren sounds different when an ambulance 269 00:13:34.720 --> 00:13:35.440 drives past you. 270 00:13:35.519 --> 00:13:39.159 Exactly like that, but with light as the planet orbits 271 00:13:39.200 --> 00:13:43.559 the star, its velocity relative to our telescopes on Earth changes. 272 00:13:44.120 --> 00:13:46.720 When it moves slightly toward us in its orbit, the 273 00:13:46.799 --> 00:13:47.919 Kban lines. 274 00:13:47.639 --> 00:13:49.879 Blue shift, and when it moves away a red shift. 275 00:13:50.200 --> 00:13:54.080 So by measuring this precise shift, astronomers can calculate the 276 00:13:54.159 --> 00:13:58.080 Keplarian velocity of the object the actual speed of its orbit. Yes, 277 00:13:58.799 --> 00:14:01.399 and the data showed that this glowing source of carbon 278 00:14:01.440 --> 00:14:05.279 monoxide was moving at the exact velocity required for an 279 00:14:05.360 --> 00:14:08.720 object in a stable bound orbit at fourteen AU. 280 00:14:09.159 --> 00:14:10.799 So it couldn't just be random gas. 281 00:14:10.960 --> 00:14:14.360 No, it was definitive proof of a massive eight to 282 00:14:14.360 --> 00:14:16.000 twelve jupiter mass planet. 283 00:14:16.279 --> 00:14:19.279 Okay, I see the logic in the detection, but the 284 00:14:19.320 --> 00:14:23.279 mass distribution still seems completely backward to me. How so, Well, 285 00:14:23.279 --> 00:14:27.039 Whispit two C is at fourteen AU, Whispit two B 286 00:14:27.320 --> 00:14:30.480 is at sixty AU. The circumference of an orbit at 287 00:14:30.519 --> 00:14:33.279 sixty AU is vastly larger, Right, Yes, it is so 288 00:14:33.320 --> 00:14:35.600 the outer planet has a much longer track to run, 289 00:14:35.720 --> 00:14:39.000 meaning as a much wider volume of space to sweep through. 290 00:14:39.879 --> 00:14:42.159 Given that, why is the inner baby so much hungrier? 291 00:14:42.360 --> 00:14:44.600 Shouldn't the planet further out have more room to sweep 292 00:14:44.639 --> 00:14:45.759 up material and get bigger. 293 00:14:46.120 --> 00:14:48.039 I get why you'd think that. It's a very common 294 00:14:48.039 --> 00:14:51.240 misconception to equate orbital circumference with available mass. 295 00:14:51.279 --> 00:14:52.039 Oh really yeah. 296 00:14:52.080 --> 00:14:54.000 In a protoplanetary disk, we have to look at the 297 00:14:54.080 --> 00:14:57.360 radial service density profile. The material, the gas, and the 298 00:14:57.440 --> 00:14:58.960 dust is not distributed even. 299 00:14:58.879 --> 00:15:01.639 Lanth It's not just a flat, uniform sheet, right. 300 00:15:02.279 --> 00:15:05.519 The disc is governed by fluid dynamics, and typically the 301 00:15:05.600 --> 00:15:08.519 surface density is highest near the star and falls off 302 00:15:08.559 --> 00:15:10.360 extonentially as you move outward. 303 00:15:10.480 --> 00:15:12.600 Ah. So the raw material is just thicker on the 304 00:15:12.600 --> 00:15:13.519 inside track. 305 00:15:13.360 --> 00:15:15.360 Thicker by orders of magnitude. 306 00:15:15.559 --> 00:15:15.960 Wow. 307 00:15:16.000 --> 00:15:20.000 To use a mechanical analogy, imagine driving a snowplow. Right, 308 00:15:20.480 --> 00:15:23.399 the outer planet at sixty AU is driving a massive 309 00:15:23.559 --> 00:15:27.360 sweeping route across a giant parking lot, but the parking 310 00:15:27.360 --> 00:15:30.759 lot only has a sparse half inch dusting of snow. Right, 311 00:15:31.000 --> 00:15:34.240 the inner planet at fourteen AU has a much shorter route, 312 00:15:34.240 --> 00:15:36.960 but it is driving through drifts that are ten feet high. 313 00:15:37.039 --> 00:15:40.480 Okay, that makes perfect sense. That tracks completely. But is 314 00:15:40.519 --> 00:15:43.639 it just a static distribution of density or is material 315 00:15:43.840 --> 00:15:45.919 actively moving toward the inner planet. 316 00:15:46.039 --> 00:15:49.039 It is highly dynamic. We have to consider radial drift, 317 00:15:49.159 --> 00:15:52.279 particularly for the pebble size solid particles in the. 318 00:15:52.240 --> 00:15:54.200 Disc radial drifts. So things are migrating. 319 00:15:54.360 --> 00:15:57.440 Yes, in the disc, the gas is partially supported by 320 00:15:57.440 --> 00:16:01.159 outward thermal pressure, meaning the gas actually orbit slightly slower 321 00:16:01.200 --> 00:16:02.799 than the cuplarian velocity. 322 00:16:02.519 --> 00:16:04.600 Slower than a purely gravitational orbit. 323 00:16:04.919 --> 00:16:08.840 Right, But the solid pebbles they don't feel that gas pressure. 324 00:16:08.919 --> 00:16:12.360 They want to orbit at the faster full caplarian velocity. 325 00:16:12.720 --> 00:16:14.720 Wait, so the pebbles are trying to go fast, but 326 00:16:14.759 --> 00:16:17.279 the gas is going slow exactly, meaning the pebbles are 327 00:16:17.279 --> 00:16:20.200 constantly fighting a headwind from the slower moving gas. 328 00:16:20.279 --> 00:16:23.159 That's the perfect way to visualize it, and that headwind 329 00:16:23.279 --> 00:16:27.519 acts as aerodynamic drag. Ah okay, it bleeds orbital angular 330 00:16:27.559 --> 00:16:31.320 momentum from the pebbles, which causes them to constantly spiral 331 00:16:31.399 --> 00:16:32.799 inward toward the star. 332 00:16:33.000 --> 00:16:33.399 Oh wow. 333 00:16:33.720 --> 00:16:36.519 So not only is wispit to see sitting in an 334 00:16:36.559 --> 00:16:40.000 inherently denser region of the disk to begin with, it 335 00:16:40.080 --> 00:16:44.360 is positioned in a cosmic bottleneck, a bottlenic right, where 336 00:16:44.600 --> 00:16:47.519 vast quantities of solid material from the outer discs are 337 00:16:47.559 --> 00:16:52.039 continually drifting inward, delivering an endless supply of mass right 338 00:16:52.080 --> 00:16:53.879 to the inner planet's feeding zone. 339 00:16:54.039 --> 00:16:55.799 So it's basically sitting at the end of a buffet 340 00:16:55.799 --> 00:16:56.600 line exactly. 341 00:16:56.840 --> 00:16:59.879 Whispit to C is gorging itself on this inward migration, 342 00:17:00.480 --> 00:17:02.559 and that allows it to rapidly balloon to ten times 343 00:17:02.679 --> 00:17:03.399 Jupiter's mass. 344 00:17:03.440 --> 00:17:05.160 Well, the outer planet is starving. 345 00:17:04.960 --> 00:17:07.559 Well, Whispit two B is forced to accrete from the 346 00:17:07.720 --> 00:17:11.400 much sparser depleted material out in the outer disc. So yes, 347 00:17:11.440 --> 00:17:12.640 it grows much slower. 348 00:17:12.759 --> 00:17:17.079 That aerodynamic drag mechanism completely changes how I view the disc. 349 00:17:17.480 --> 00:17:20.720 It's not a static ring. It's a conveyor belt. It 350 00:17:20.759 --> 00:17:24.279 absolutely is, and the planets are actively disrupting that conveyor belt, 351 00:17:24.960 --> 00:17:27.759 which naturally brings us to the visual architecture of the 352 00:17:27.759 --> 00:17:31.079 Wispit two disc. We talked about how we're seeing these 353 00:17:31.160 --> 00:17:35.279 visible scars these planets are leaving behind. We see these massive, bright, 354 00:17:35.680 --> 00:17:39.519 concentric rings of dust separated by deep, dark gaps. Right 355 00:17:40.000 --> 00:17:43.160 if we picture a giant vinyl record, the dust makes 356 00:17:43.240 --> 00:17:45.519 up the ridges, and the planets are the needles carving 357 00:17:45.519 --> 00:17:48.319 out the grooves, pulling in mass as gravity takes over. 358 00:17:49.000 --> 00:17:52.079 But how exactly does a planet's gravity physically clear a 359 00:17:52.160 --> 00:17:55.039 gap that is billions of miles wide. I mean, it 360 00:17:55.079 --> 00:17:57.200 can't possibly accrete all that material, can it? 361 00:17:57.319 --> 00:17:59.279 Oh? No, it doesn't accrete all of it. In fact, 362 00:17:59.319 --> 00:18:01.279 it it cretes relatively small fraction. 363 00:18:01.440 --> 00:18:02.519 So where does the rest of it go? 364 00:18:02.960 --> 00:18:05.759 The vast majority of the material is pushed away through 365 00:18:05.799 --> 00:18:06.880 gravitational torques. 366 00:18:07.359 --> 00:18:07.559 Yes. 367 00:18:08.480 --> 00:18:11.359 When a massive planet like Wisp it two B or 368 00:18:11.400 --> 00:18:15.480 two C orbits within a gaseous disc, it interacts gravitationally 369 00:18:15.559 --> 00:18:19.680 with the surrounding material and it launches spiral density waves. 370 00:18:19.880 --> 00:18:21.920 Spiral density waves, that sounds intense. 371 00:18:22.119 --> 00:18:24.920 They are. These waves are very similar to the wake 372 00:18:25.039 --> 00:18:28.200 created by a boat moving through water. As these density 373 00:18:28.200 --> 00:18:31.279 waves propagate away from the planet, both inward toward the 374 00:18:31.279 --> 00:18:35.279 star and outward into the deeper disc, they eventually shock 375 00:18:35.319 --> 00:18:35.799 the gas. 376 00:18:36.200 --> 00:18:38.640 They shock it, meaning they compress it and transfer momentum. 377 00:18:38.839 --> 00:18:41.960 Yes, the waves deposit angular momentum into the outer disc, 378 00:18:42.039 --> 00:18:44.680 which physically pushes the gas further away from the star. 379 00:18:44.839 --> 00:18:45.400 Oh okay. 380 00:18:45.680 --> 00:18:48.640 And conversely, they extract angular momentum from the inner disc, 381 00:18:49.000 --> 00:18:51.039 causing that gas to fall closer to the star. 382 00:18:51.200 --> 00:18:53.640 This is pushing material in both directions away from its 383 00:18:53.759 --> 00:18:54.720 orbit exactly. 384 00:18:54.799 --> 00:18:57.200 The net result is that the gas is actively repelled 385 00:18:57.200 --> 00:18:59.799 from the planet's orbit, creating a cleared region or a 386 00:18:59.839 --> 00:19:00.480 gar app. 387 00:19:00.400 --> 00:19:02.359 But the images we are seeing from the telescopes are 388 00:19:02.359 --> 00:19:06.359 primarily showing dust, not just gas, right, correct, So how 389 00:19:06.400 --> 00:19:10.039 does pushing the gas away create those incredibly sharp bright 390 00:19:10.160 --> 00:19:12.960 rings of dust on either side of the gap? Ah? 391 00:19:13.240 --> 00:19:15.880 This ties directly back to the aerodynamic. 392 00:19:15.279 --> 00:19:17.240 Drag we just discussed the headwinds. Right. 393 00:19:17.880 --> 00:19:20.920 When the planet pushes the gas away and creates a gap, 394 00:19:21.279 --> 00:19:24.319 it creates a localized pressure gradient at the edge. 395 00:19:24.200 --> 00:19:26.319 Of that gap, meaning the gas pressure spikes. 396 00:19:26.480 --> 00:19:31.839 Yes, the gas pressure increases sharply just outside the cleared zone. Now, 397 00:19:31.920 --> 00:19:35.240 remember that solid pebbles drift inward due to the. 398 00:19:35.200 --> 00:19:37.160 Gas headwind, right the spiraling in. 399 00:19:37.440 --> 00:19:40.839 But when those inward drifting pebbles hit that sudden spike 400 00:19:40.920 --> 00:19:43.000 in gas pressure at the outer edge of the gap, 401 00:19:43.359 --> 00:19:47.079