WEBVTT 1 00:00:03.399 --> 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 --> 00:00:28.440 Okay, let's unpack this. 8 00:00:28.600 --> 00:00:29.120 Let's do it. 9 00:00:29.199 --> 00:00:33.439 When you and I are really anyone pictures a star dying, 10 00:00:33.799 --> 00:00:37.399 you know, in a supernova, we're usually imagining just the 11 00:00:37.439 --> 00:00:40.479 most extreme catastrophic event. 12 00:00:40.320 --> 00:00:42.119 Possible, ultimate cosmic destruction. 13 00:00:42.200 --> 00:00:45.840 Yeah, right, a massive, completely chaotic mess. It's this expanding 14 00:00:45.880 --> 00:00:49.880 cloud of superheated debris. And I love the term astrophysicists use. 15 00:00:50.119 --> 00:00:53.280 They say it has a texture like a giant turbulent cauliflower. 16 00:00:53.359 --> 00:00:56.320 It's a great visual and it's accurate. That's the standard 17 00:00:56.359 --> 00:00:58.679 picture of stellar violence we expect to see. 18 00:00:58.799 --> 00:01:01.520 But the sources you've shared with us today, they focus 19 00:01:01.560 --> 00:01:06.000 on this one astronomical object that just it throws that 20 00:01:06.200 --> 00:01:08.280 entire visual model right out the window completely. 21 00:01:08.359 --> 00:01:08.560 Yeah. 22 00:01:08.599 --> 00:01:11.799 It's called pop thirty. And this thing, this remnant, is 23 00:01:11.840 --> 00:01:14.239 the perfect visual opposite of chaos. It looks like, yeah, 24 00:01:14.439 --> 00:01:16.760 like an explosion that was frozen right in the middle 25 00:01:16.760 --> 00:01:17.239 of the burst. 26 00:01:17.319 --> 00:01:18.519 That's a perfect description. 27 00:01:18.840 --> 00:01:22.079 It's not defined by swirling clouds at all, but by 28 00:01:22.120 --> 00:01:28.519 these incredibly long, straight, almost almost geometrically precise filaments, all 29 00:01:28.640 --> 00:01:30.680 radiating outward from one single point. 30 00:01:31.040 --> 00:01:35.040 And this exploration it's really a perfect example of connecting 31 00:01:35.480 --> 00:01:38.879 centuries old observations from the sky with the most cutting 32 00:01:38.959 --> 00:01:40.319 edge computational physics we. 33 00:01:40.280 --> 00:01:42.319 Have today, a real bridge between the old and new. 34 00:01:42.560 --> 00:01:46.680 Absolutely, our whole mission here is to figure out this paradox. 35 00:01:47.159 --> 00:01:50.599 How can a stellar explosion, one of the most energetic 36 00:01:50.680 --> 00:01:54.319 events in the entire universe, end up creating something with 37 00:01:54.439 --> 00:01:57.799 such incredible structural order, right, So we need to figure 38 00:01:57.799 --> 00:01:59.799 out not just what happened to the star that created, 39 00:02:00.439 --> 00:02:03.480 which was a white dwarf, but why the debris cloud 40 00:02:03.519 --> 00:02:06.359 it left behind looks so radically different from pretty much 41 00:02:06.400 --> 00:02:07.719 every other remnant we study. 42 00:02:08.039 --> 00:02:10.719 So this is a deep dive into stellar failure. 43 00:02:10.520 --> 00:02:14.000 It is, and how that failure, weirdly enough became the 44 00:02:14.039 --> 00:02:17.759 necessary first step for creating this spectacular geometry. 45 00:02:17.919 --> 00:02:21.039 And this is where it gets for me, just genuinely fascinating. 46 00:02:21.240 --> 00:02:25.120 We're talking about physics on this immense cosmic scale, with 47 00:02:25.280 --> 00:02:28.280 material moving faster than any rocket ship we've ever dreamed of. 48 00:02:28.240 --> 00:02:29.639 Building on believable speeds. 49 00:02:29.800 --> 00:02:32.919 But the key mechanism, the thing that explains Path thirty's 50 00:02:33.039 --> 00:02:36.719 unique precise shape, is the exact same principle of fluid 51 00:02:36.800 --> 00:02:40.680 dynamics that creates the classic iconic shape of a mushroom 52 00:02:40.680 --> 00:02:41.879 cloud right here on Earth. 53 00:02:41.919 --> 00:02:44.319 It's the same physics, just on a scale that's hard 54 00:02:44.360 --> 00:02:45.280 to even comprehend. 55 00:02:45.360 --> 00:02:47.879 So let's get into it. Let's explore the really complex 56 00:02:47.960 --> 00:02:52.039 astrophysics that turned what should have been this violent explosion 57 00:02:52.560 --> 00:02:57.759 into a geometrically structured whimper, a very beautiful whimper. We 58 00:02:57.879 --> 00:03:00.639 really have to start with that visual contra because it 59 00:03:00.759 --> 00:03:04.960 is so so striking. It puzzled astronomers for decades, for 60 00:03:05.000 --> 00:03:07.199 a long long time. If you pull up images of 61 00:03:07.240 --> 00:03:10.240 remnants from what we call typical type ees supernovae, that's 62 00:03:10.240 --> 00:03:12.800 the kind of where the star is completely obliterated, you 63 00:03:12.840 --> 00:03:14.240 see exactly what we're talking about. 64 00:03:14.240 --> 00:03:15.039 The cauliflower. 65 00:03:15.080 --> 00:03:18.840 The cauliflower, Yeah, thick, churning, chaotic clouds of ejecta. It's 66 00:03:18.879 --> 00:03:22.520 the perfect image of massive cosmic turbulence and mixing gas. 67 00:03:23.000 --> 00:03:25.319 This is what's supposed to happen when a star completely 68 00:03:25.360 --> 00:03:26.960 and violently tears itself apart. 69 00:03:27.159 --> 00:03:29.840 And you have to appreciate the energy involved there. A 70 00:03:29.879 --> 00:03:33.800 standard type E S supernova, I mean, it releases an 71 00:03:33.840 --> 00:03:37.479 amount of energy and milliseconds that's equivalent to what our 72 00:03:37.520 --> 00:03:40.840 Sun will put out over its entire multi billion year lifetime. 73 00:03:40.960 --> 00:03:42.560 It's just an insane amount of power. 74 00:03:42.639 --> 00:03:47.120 It's incredible. And that sheer instantaneous energy churns up all 75 00:03:47.199 --> 00:03:50.800 the ejected material so intensely that any little bit of 76 00:03:50.840 --> 00:03:53.000 structure it might have had at the beginning is just 77 00:03:53.879 --> 00:03:56.800 it's ripped apart. It's thoroughly mixed, and that's what leads 78 00:03:56.800 --> 00:03:58.759 to that characteristic chaotic mess. 79 00:03:58.800 --> 00:04:01.120 And these are the explosions we rely on right as 80 00:04:01.159 --> 00:04:02.639 cosmic yardsticks we do. 81 00:04:02.680 --> 00:04:05.879 We call them standard candles because their brightness is so predictable, 82 00:04:06.080 --> 00:04:09.159 which lets us measure distances across the universe. But the 83 00:04:09.240 --> 00:04:12.240 debris fields they leave behind are anything but standard in 84 00:04:12.280 --> 00:04:15.879 their structure. They are, you know, textbook models of total 85 00:04:15.960 --> 00:04:18.720 cosmic chaos with Then you turn. 86 00:04:18.560 --> 00:04:21.439 Your telescope to path thirty and it is just so 87 00:04:21.839 --> 00:04:25.079 distinctively lacking any of those chaotic signatures. It's not a 88 00:04:25.079 --> 00:04:28.120 cauliflower at all, not even close. Instead, you get these 89 00:04:28.120 --> 00:04:33.879 incredibly long, sustained straight filaments. They just they radiate outward 90 00:04:33.959 --> 00:04:36.920 from a central point. The researchers described it perfectly. I 91 00:04:36.920 --> 00:04:39.240 think they said, it's like the trails from a sparkler 92 00:04:39.240 --> 00:04:40.480 that have been frozen midburst. 93 00:04:40.720 --> 00:04:44.199 And that appearance right away it signals a huge anomaly. 94 00:04:44.800 --> 00:04:48.120 For years, astronomers really struggle to explain the structure precisely 95 00:04:48.120 --> 00:04:51.439 because it defied all the standard high energy supernova models. 96 00:04:51.519 --> 00:04:54.319 The question must have been, why is there any structure at. 97 00:04:54.279 --> 00:04:56.720 All, exactly and how did it stay so straight, so 98 00:04:56.800 --> 00:04:59.920 linear across these vast distances and over so much time. 99 00:05:00.519 --> 00:05:03.519 What's so fascinating here is that we can trace PAW 100 00:05:03.600 --> 00:05:07.600 thirty's timeline way back in history. We now know that 101 00:05:07.639 --> 00:05:11.079 the event itself corresponds to something that Chinese and Japanese 102 00:05:11.079 --> 00:05:13.839 astronomers observed way back in the year eleven eighty one. 103 00:05:14.279 --> 00:05:15.959 They called it a guest star. 104 00:05:16.319 --> 00:05:19.160 So we're talking about almost nine hundred and fifty years 105 00:05:19.160 --> 00:05:22.279 of observation here, starting with ancient records and leading all 106 00:05:22.279 --> 00:05:24.279 the way up to the Hi Ris images. We have today. 107 00:05:24.319 --> 00:05:27.439 That's right, okay, So if the event was observed back then, 108 00:05:28.120 --> 00:05:30.759 do those historical records tell us anything about what kind 109 00:05:30.759 --> 00:05:32.600 of explosion it was. Did it look like a normal 110 00:05:32.639 --> 00:05:33.720 supernova to them? 111 00:05:33.800 --> 00:05:36.639 And that is a crucial piece of the puzzle. The 112 00:05:36.680 --> 00:05:39.319 historical records actually support the idea that this was an 113 00:05:39.399 --> 00:05:43.199 unusual event even back then. The brightness records from eleven 114 00:05:43.240 --> 00:05:46.199 eighty one. They indicate that this guest star, which we 115 00:05:46.240 --> 00:05:49.399 now link to PAW thirty with very high confidence, it 116 00:05:49.439 --> 00:05:52.639 was visible for many months. But this is the critical part. 117 00:05:53.120 --> 00:05:56.879 It never got as bright as a standard fully detonating 118 00:05:57.000 --> 00:05:57.959 type iis. 119 00:05:57.680 --> 00:05:59.600 Supernova ah so is dimmer. 120 00:06:00.079 --> 00:06:03.000 It was notably dimmer. This suggests it had a lower 121 00:06:03.040 --> 00:06:06.040 total energy release, or what we'd call a lower peak luminosity. 122 00:06:06.360 --> 00:06:09.000 This observational fact is one of the key clues. The 123 00:06:09.040 --> 00:06:11.439 explosion was powerful enough to be seen from Earth, but 124 00:06:11.480 --> 00:06:13.160 it was not powerful enough to be one of these 125 00:06:13.199 --> 00:06:15.519 full scale star obliterating events. 126 00:06:15.639 --> 00:06:19.279 So the ancient astronomers gave us our first clue, a dimmer, 127 00:06:19.560 --> 00:06:24.279 longer lasting blast, and modern astronomersy the aftermath a strangely 128 00:06:24.399 --> 00:06:26.000 geometric remnant. 129 00:06:25.759 --> 00:06:29.160 Exactly that ninth century gap between the observation and the 130 00:06:29.160 --> 00:06:32.480 final explanation really highlights how complex this problem was. 131 00:06:32.560 --> 00:06:35.480 But the recent research, the work spearheaded by Eric Coughlin 132 00:06:35.519 --> 00:06:38.839 and his team at Syracuse University, that's what finally provides 133 00:06:38.879 --> 00:06:41.879 the unifying concept. It does, and the core finding is 134 00:06:42.160 --> 00:06:47.120 just it's so simple and profound. The star tried to explode, 135 00:06:47.519 --> 00:06:49.000 but it didn't fully succeed. 136 00:06:49.279 --> 00:06:53.120 That that is the critical transformative insight. The star did 137 00:06:53.160 --> 00:06:55.720 not follow the textbook. It was an incomplete blast. This 138 00:06:55.879 --> 00:06:59.839 wasn't just a misfire. It's a specific, recognized class of 139 00:06:59.800 --> 00:07:04.600 stellar death that creates the perfect conditions for this very unique, 140 00:07:05.000 --> 00:07:06.279 very precise geometry. 141 00:07:06.480 --> 00:07:08.959 So the fact that the explosion was a partial event, 142 00:07:09.600 --> 00:07:11.199 a failure if you want to call it that. 143 00:07:11.319 --> 00:07:12.680 A failure is a good word for it. 144 00:07:12.879 --> 00:07:15.399 That's what ultimately dictated the fluid physics of the remnant 145 00:07:15.399 --> 00:07:17.199 we see today. If it had been a full scale 146 00:07:17.240 --> 00:07:20.759 Type IAD detonation, there would be no Poth thirty, there would. 147 00:07:20.560 --> 00:07:23.720 Just be another chaotic cauliflower cloud and the star itself 148 00:07:23.759 --> 00:07:24.639 would be gone forever. 149 00:07:24.839 --> 00:07:28.360 So the visual signature, this beautiful geometric order, is a 150 00:07:28.399 --> 00:07:32.079 direct consequence of a failure in nuclear physics. That's the 151 00:07:32.160 --> 00:07:36.079 foundation that explains this whole nine hundred year old mystery. 152 00:07:35.680 --> 00:07:38.120 It is, and to really appreciate the details of that failure, 153 00:07:38.120 --> 00:07:41.199 we should probably quickly walk through the standard type IA 154 00:07:41.279 --> 00:07:43.879 process first, and then we can see exactly where POTH 155 00:07:43.920 --> 00:07:44.959 thirty went off the rails. 156 00:07:44.959 --> 00:07:46.480 Good idea. So where does this start? 157 00:07:46.759 --> 00:07:50.160 It starts with a white dwarf. Pal thirty came from 158 00:07:50.199 --> 00:07:53.800 a white dwarf, which is the super dense, extremely compact 159 00:07:53.839 --> 00:07:57.480 core leftover after a star like our sun, runs out 160 00:07:57.480 --> 00:07:58.480 of its nuclear fuel. 161 00:07:58.639 --> 00:08:00.959 And the classic story of white dwarf is that it's 162 00:08:00.959 --> 00:08:04.040 supposed to be retired, right It just sits there quietly, 163 00:08:04.319 --> 00:08:07.439 supported by something called electron degeneracy pressure. 164 00:08:07.720 --> 00:08:11.959 Unless unless it has a friend, a companion star. If 165 00:08:11.959 --> 00:08:14.759 it's in a binary system, it can start pulling material 166 00:08:15.040 --> 00:08:17.759 like hydrogen and helium from that companion. 167 00:08:17.959 --> 00:08:20.560 It starts a creating mass exactly. 168 00:08:20.040 --> 00:08:22.519 And when it gathers enough mass, it creeps closer and 169 00:08:22.560 --> 00:08:26.079 closer to this critical threshold called the chondraceccar limit that's 170 00:08:26.120 --> 00:08:28.399 about one point four times the mass of our side. 171 00:08:28.439 --> 00:08:29.920 And once it hits that limit, the. 172 00:08:29.839 --> 00:08:33.159 Core can't resist gravity anymore. The pressure in the heat 173 00:08:33.200 --> 00:08:36.279 becomes so immense that it triggers runaway carbon fusion deep 174 00:08:36.279 --> 00:08:37.519 inside the star, and in. 175 00:08:37.480 --> 00:08:41.200 A normal type event, that first little spark of ignition 176 00:08:41.759 --> 00:08:45.120 very quickly turns into what's called a supersonic detonation wave. 177 00:08:45.240 --> 00:08:48.200 Supersonic is the keyword there. It's a wave traveling faster 178 00:08:48.279 --> 00:08:50.759 than the speed of sound through the star's material, like 179 00:08:50.759 --> 00:08:54.320 a shock wave of fire a perfect analogy. That detonation 180 00:08:54.480 --> 00:08:57.000 wave just sweeps through the entire star in a matter 181 00:08:57.080 --> 00:09:01.519 of seconds, converting carbon and oxygen into heavier elements, mostly 182 00:09:01.600 --> 00:09:05.200 nickel fifty six. This process concerns the whole white dwarf, 183 00:09:05.240 --> 00:09:08.960 completely obliterating it and scattering all that newly forged material 184 00:09:09.000 --> 00:09:10.039 across space. 185 00:09:09.879 --> 00:09:12.440 And that's what creates those chaotic debris clouds we talked about. 186 00:09:12.519 --> 00:09:16.559 The star is just gone bitterly destroyed. But Path thirty 187 00:09:16.639 --> 00:09:19.120 star took a different path. This is what classifies it 188 00:09:19.159 --> 00:09:23.519 as the distinct type IAX supernova. So what happened to 189 00:09:23.559 --> 00:09:24.559 that detonation wave. 190 00:09:25.000 --> 00:09:26.960 Well, in the case of Path thirty and other Type 191 00:09:27.000 --> 00:09:30.840 IX events, the initial nuclear burning did begin. It started 192 00:09:30.879 --> 00:09:33.519 near the star surface in a process we call a deflagration. 193 00:09:34.080 --> 00:09:36.559 Think of it like a fast moving flame front, not 194 00:09:36.600 --> 00:09:37.279 a shock wave. 195 00:09:37.360 --> 00:09:39.840 So it's burning, but it's subsonic, yes, slower than the. 196 00:09:39.840 --> 00:09:43.120 Speed of sound exactly. And this is the crucial failure point. 197 00:09:43.399 --> 00:09:47.120 That subsonic burning front, for whatever reason, failed to transition 198 00:09:47.240 --> 00:09:51.080 into a full supersonic detonation wave that would have propagated 199 00:09:51.120 --> 00:09:51.960 through the rest of the star. 200 00:09:52.159 --> 00:09:54.600 It lit the fuse, but the bomb didn't go off properly. 201 00:09:54.799 --> 00:09:58.000 That's it. The burning front stalled, or maybe it was 202 00:09:58.080 --> 00:10:00.559 just too slow and inefficient, so instead of a complete 203 00:10:00.600 --> 00:10:06.039 stellar detonation, you get this partial subsurface explosion. The source 204 00:10:06.080 --> 00:10:08.840 material calls it a fizzle, which you know, is still 205 00:10:08.879 --> 00:10:12.159 a tremendously powerful event by our standards, but on a 206 00:10:12.159 --> 00:10:13.799 cosmic scale, it's a failure. 207 00:10:14.320 --> 00:10:17.200 And the incredible immediate result of this fizzle is the 208 00:10:17.240 --> 00:10:22.360 real key to path thirties geometry. The star itself wasn't destroyed. 209 00:10:22.559 --> 00:10:26.399 That's the most important physical outcome. The star survived a 210 00:10:26.559 --> 00:10:30.840 hypermassive white dwarf, profoundly shaken, partially burned, certainly changed by 211 00:10:30.879 --> 00:10:34.559 the energy release, but it survived that initial failed blast 212 00:10:34.600 --> 00:10:37.039 and it is still sitting there intact at the very 213 00:10:37.080 --> 00:10:40.120 center of the remnant today. Wow and this phenomenon, the 214 00:10:40.159 --> 00:10:42.320 lower brightness of the explosion and the survival of the 215 00:10:42.360 --> 00:10:45.600 stellar core. That is the defining feature of these type 216 00:10:45.639 --> 00:10:48.639 IX supernovae. They're rare, you know. They only account for 217 00:10:48.639 --> 00:10:51.080 a small fraction of all the white dwarf explosions we've seen, 218 00:10:51.120 --> 00:10:52.919 but we're recognizing more of them as we get more 219 00:10:53.000 --> 00:10:55.879 data on these unusual ways for stars to die. 220 00:10:56.000 --> 00:10:59.879 It's a spectacular failure and it gives us this incredibly rare, 221 00:11:00.600 --> 00:11:05.080 detailed data point. But let me challenge the premise a 222 00:11:05.080 --> 00:11:08.039 little bit. Please, If the explosion failed, if it was 223 00:11:08.120 --> 00:11:11.159 just a fizzle, where did all the energy come from 224 00:11:11.200 --> 00:11:14.679 to launch this sustained outflow of material moving at fifteen 225 00:11:14.720 --> 00:11:19.360 thousand kilometers per second. That speed is just immense This 226 00:11:19.639 --> 00:11:23.000 vastly faster than the Earth orbits the Sun. A failed 227 00:11:23.000 --> 00:11:25.360 blast shouldn't be able to generate that kind of power 228 00:11:25.399 --> 00:11:26.559 over a long time, should it. 229 00:11:26.840 --> 00:11:29.000 That is a brilliant question, and it gets to the 230 00:11:29.039 --> 00:11:32.000 really complex transient physics that happened in the moments right 231 00:11:32.080 --> 00:11:35.639 after the failed blast. The energy source is a combination 232 00:11:35.840 --> 00:11:38.840 of that initial partial burn and the dynamics of the 233 00:11:38.840 --> 00:11:41.679 star that's left over. Okay, so when that subsurface nuclear 234 00:11:41.720 --> 00:11:45.480 burn happened. It created this massive, superheated, dense shell of 235 00:11:45.519 --> 00:11:48.600 heavy elements, mostly near the stars surface. But because the 236 00:11:48.639 --> 00:11:51.799 full detonation wave never happened, that heavy shell didn't just 237 00:11:51.879 --> 00:11:54.360 fly off into space cleanly. Some of it fell back, 238 00:11:54.480 --> 00:11:56.759 a lot of it expanded violently, and then, yes, a 239 00:11:56.799 --> 00:11:59.279 significant portion of it began to fall back onto the 240 00:11:59.320 --> 00:12:02.200 surviving cour due to its immense gravity, so you get 241 00:12:02.200 --> 00:12:05.960 a rebound effect exactly. The failed blast creates this massive 242 00:12:05.960 --> 00:12:09.600 pressure wave that travels inward, bounces off the surviving still 243 00:12:09.639 --> 00:12:13.279 intact core, and then rebounds as a hyper fast, outward 244 00:12:13.320 --> 00:12:14.759 moving shockwave. 245 00:12:14.360 --> 00:12:16.320 Like a cosmic pogo stick in a way. 246 00:12:16.519 --> 00:12:19.679 Yes, this intense shockwave, which is driven by the post 247 00:12:19.759 --> 00:12:23.440 explosion thermal pressure and these fallback dynamics, it acts like 248 00:12:23.480 --> 00:12:27.440 a cosmic cannon. It immediately starts launching an extraordinarily fast, 249 00:12:27.480 --> 00:12:30.559 dense wind of that partially burned material out into space. 250 00:12:31.000 --> 00:12:34.159 And this sustained stellar wind moving its speeds up to 251 00:12:34.279 --> 00:12:37.759 fifteen thousand kilometers per second. That is the true engine 252 00:12:37.799 --> 00:12:39.600 that creates the geometry we see today. 253 00:12:39.639 --> 00:12:42.039 And we also know the composition, which I think is 254 00:12:42.080 --> 00:12:45.519 critical for what comes next. This wind wasn't just hydrogen. 255 00:12:45.600 --> 00:12:47.519 It was enriched with heavy elements. 256 00:12:47.720 --> 00:12:51.440 Yes, absolutely, the material being launched at these hypervelocities was 257 00:12:51.440 --> 00:12:54.200 made of the very elements forged during that brief failed 258 00:12:54.240 --> 00:12:57.519 nuclear burn near the surface, things like iron, silicon, other 259 00:12:57.559 --> 00:12:58.200 heavy products. 260 00:12:58.279 --> 00:13:01.399 So you have a tremendously fast, heavy, and crucially a 261 00:13:01.559 --> 00:13:04.879 dense stream of material being continuously shot outward from the 262 00:13:04.919 --> 00:13:06.320 star that refused to die. 263 00:13:06.440 --> 00:13:11.519 That's the perfect combination hypervelocity, high density, and sustained duration. 264 00:13:12.399 --> 00:13:15.879 That sets the stage perfectly for the unique geometry, which 265 00:13:15.919 --> 00:13:19.559 is governed by some very basic but very powerful principles 266 00:13:19.559 --> 00:13:20.639 of fluid dynamics. 267 00:13:20.720 --> 00:13:23.399 It really transforms the surviving white dwarf. It's not just 268 00:13:23.440 --> 00:13:27.279 a remnant anymore. It's become a perpetual high speed fluid injector. 269 00:13:27.320 --> 00:13:28.399 That's exactly what it is. 270 00:13:28.720 --> 00:13:31.000 So let's make that transition. Then we go from a 271 00:13:31.039 --> 00:13:35.120 failure in nuclear physics to a success in fluid dynamics. 272 00:13:35.639 --> 00:13:38.080 We have this surviving white dwarf. It's launching a wind 273 00:13:38.080 --> 00:13:40.919 at fifteen thousand kilometers per second. It's dense, it's rich 274 00:13:40.919 --> 00:13:44.879 and heavy elements. When this dense, fast wind slams outward 275 00:13:45.000 --> 00:13:48.519 into the lighter much much sparser gas that's just sitting 276 00:13:48.519 --> 00:13:52.360 around in that area the interstellar medium. That surface where 277 00:13:52.360 --> 00:13:54.720 they meet becomes a physics laboratory. 278 00:13:54.240 --> 00:13:56.960 It does. That interface is where all the action happens. 279 00:13:57.000 --> 00:14:00.320 It's where the characteristic Sparkler structure of Paul thirty is born. 280 00:14:00.600 --> 00:14:03.679 From this point on, fluid dynamics dictates everything about the 281 00:14:03.759 --> 00:14:04.960 remnant's shape. 282 00:14:04.600 --> 00:14:07.559 And that meeting point where the dense fast stuff hits 283 00:14:07.600 --> 00:14:10.559 the sparse slow stuff. It's not stable, is it not 284 00:14:10.639 --> 00:14:10.960 at all? 285 00:14:11.000 --> 00:14:15.279 It's highly unstable, and that inherent instability is the absolute 286 00:14:15.360 --> 00:14:18.000 key to forming those long, straight filaments. 287 00:14:18.320 --> 00:14:21.600 Okay, let's talk about that first critical instability, the one 288 00:14:21.600 --> 00:14:24.080 that connects this cosmic event to something we can actually 289 00:14:24.200 --> 00:14:28.320 visualize here on Earth. The Raleigh Tailor instability or RT. 290 00:14:28.759 --> 00:14:32.159 The Raley tailor instability is a really fundamental phenomenon in 291 00:14:32.200 --> 00:14:35.399 fluid dynamics. It describes what happens when you have two 292 00:14:35.480 --> 00:14:38.919 fluids of different densities and you have an acceleration force 293 00:14:38.960 --> 00:14:41.639 that's directed from the dense fluid toward the light fluid. 294 00:14:41.799 --> 00:14:44.320 It sounds technical, but the idea is simple. 295 00:14:44.399 --> 00:14:47.200 It is, if a dense fluid pushes into a lighter fluid, 296 00:14:47.519 --> 00:14:50.879 or if you have some acceleration force acting across that boundary, 297 00:14:51.240 --> 00:14:54.639 the interface between them becomes unstable and the two fluids 298 00:14:54.720 --> 00:14:56.720 will try to mix in a very particular way. 299 00:14:56.960 --> 00:15:00.159 And the classic macroscopic example that everyone knows, even they 300 00:15:00.159 --> 00:15:02.240 don't know the scientific term for it is the shape 301 00:15:02.279 --> 00:15:04.600 of a mushroom cloud from a nuclear explosion. 302 00:15:04.759 --> 00:15:08.480 Correct that iconic mushroom shape is driven almost entirely by 303 00:15:08.600 --> 00:15:12.600 RT instability. The intense heat of the initial blast creates 304 00:15:12.639 --> 00:15:16.559 this massive bubble of hot, low density gas inside. 305 00:15:16.120 --> 00:15:18.399 The fireball, and hot air rises. 306 00:15:18.240 --> 00:15:21.799 Right it rises rapidly through the cooler, much denser surrounding air. 307 00:15:22.480 --> 00:15:25.960 In that case, gravity provides the acceleration, effectively pulling the 308 00:15:25.960 --> 00:15:29.600 denser air down and around the lighter rising fluid, and 309 00:15:29.639 --> 00:15:33.120 that density difference, coupled with the acceleration, causes the boundary 310 00:15:33.159 --> 00:15:36.440 to become unstable and form those characteristic swirling shapes and 311 00:15:36.480 --> 00:15:39.480 the big fingers or plumes that make up the mushroom cap. 312 00:15:39.720 --> 00:15:43.440 Okay, So if P thirty is basically a colossal cosmic 313 00:15:43.519 --> 00:15:46.519 version of that, we have to address one key difference 314 00:15:47.000 --> 00:15:50.600 in space. On this scale, gravity is pretty much irrelevant 315 00:15:50.600 --> 00:15:53.720 compared to the kinetic forces. At play. So what force 316 00:15:53.840 --> 00:15:57.279 is replacing gravity to define that density interface and drive 317 00:15:57.279 --> 00:15:58.080 the instability. 318 00:15:58.320 --> 00:16:00.399 That is the essential insight you need when you apply 319 00:16:00.559 --> 00:16:04.559 terrestrial fluid physics to astrophysics. In Better thirty, the acceleration 320 00:16:04.679 --> 00:16:07.639 isn't provided by a universal force like gravity. It's provided 321 00:16:07.639 --> 00:16:11.440 by the relentless, sustained kinetic pressure of that outgoing stellar wind. 322 00:16:11.600 --> 00:16:13.000 So the wind itself is the force. 323 00:16:13.519 --> 00:16:17.080 Yes, the dense high speed wind acts like a piston. 324 00:16:17.759 --> 00:16:21.639 It's forcefully accelerating the lighter interstellar material out of its way. 325 00:16:22.039 --> 00:16:24.919 The rapid deceleration of that heavy wind as it smacks 326 00:16:24.960 --> 00:16:29.039 into the lighter gas that creates the necessary conditions for 327 00:16:29.159 --> 00:16:32.399 RT instability to kick off. Right at that boundary. The 328 00:16:32.399 --> 00:16:35.639 inertia of the dense, fast moving wind is so immense 329 00:16:35.759 --> 00:16:38.879 that it acts as the primary driving force pushing into 330 00:16:38.919 --> 00:16:40.399 the static light medium. 331 00:16:40.679 --> 00:16:43.799 So the energy injection itself is the accelerating force. The 332 00:16:43.840 --> 00:16:47.399 dense heavy wind pushing the light ambient gas forward is 333 00:16:47.399 --> 00:16:49.480 what causes those initial fingers to sprout. 334 00:16:49.720 --> 00:16:53.080 Precisely, the conditions at the boundary between the dense fast 335 00:16:53.159 --> 00:16:56.679 stellar wind and the surrounding interstellar gas were just perfect 336 00:16:56.679 --> 00:16:59.720 for RT instability. You have a dense, heavier wind pushing 337 00:16:59.759 --> 00:17:03.240 forward fully and continuously into a lighter surrounding material. This 338 00:17:03.360 --> 00:17:06.799 interaction causes prumes or fingers to develop at the interface, 339 00:17:06.799 --> 00:17:08.720 and they stretch out into the material ahead of them. 340 00:17:08.759 --> 00:17:10.720 And in Paul thirty, those are the plumes that grew 341 00:17:10.759 --> 00:17:13.160 into the long, straight filaments we see today. 342 00:17:13.279 --> 00:17:14.720 They are the very same structures. 343 00:17:14.799 --> 00:17:17.480 Yes, but that immediately brings us right back to the 344 00:17:17.519 --> 00:17:21.759 central puzzle of Path thirty. If our key instability creates 345 00:17:21.759 --> 00:17:26.039 these fingers, why are they long, straight and sustained In 346 00:17:26.079 --> 00:17:29.119 most supernova remnants we look at those RT fingers might 347 00:17:29.160 --> 00:17:31.759 appear for a split second, but then they're immediately ripped 348 00:17:31.759 --> 00:17:33.359 apart and mixed into total chaos. 349 00:17:33.480 --> 00:17:35.119 That's right. They're incredibly transient. 350 00:17:35.200 --> 00:17:36.559 So if you just look at the physics of a 351 00:17:36.599 --> 00:17:40.119 normal explosion, all of this beautiful order should just break 352 00:17:40.160 --> 00:17:40.920 down immediately. 353 00:17:41.119 --> 00:17:43.720 And that is the fundamental difference that makes path thirty 354 00:17:43.960 --> 00:17:46.960 so important for us to study. We are witnessing a 355 00:17:46.960 --> 00:17:50.599 physical condition that is actively suppressing the subsequent processes that 356 00:17:50.720 --> 00:17:55.160 normally generate chaos. Path thirty stays orderly because something is 357 00:17:55.240 --> 00:17:57.359 preventing those fingers from being sheared apart. 358 00:17:57.759 --> 00:18:00.279 It's the difference between a high energy explosion it just 359 00:18:00.359 --> 00:18:05.039 immediately collapses into this disorganized turbulence and a continuous, sustained 360 00:18:05.079 --> 00:18:09.559 process that maintains that structure well for nine centuries in counting. 361 00:18:09.960 --> 00:18:12.440 And this brings us to the key physical insight that 362 00:18:12.480 --> 00:18:17.480 the computational modeling uncovered. The preservation mechanism is the extreme 363 00:18:17.759 --> 00:18:21.279 high density contrast between the two materials, and it's the 364 00:18:21.319 --> 00:18:25.279 effect that has on a second, usually dominant instability. 365 00:18:25.559 --> 00:18:27.880 Okay, you mentioned a second instability, the one that usually 366 00:18:27.880 --> 00:18:31.799 causes all the chaos. Let's name it and define what 367 00:18:31.880 --> 00:18:33.640 it normally does in a typical remnant. 368 00:18:33.759 --> 00:18:36.400 We have to talk about the Kelvin Helmholtz instability or 369 00:18:36.480 --> 00:18:40.480 k H. It's another fundamental concept where a Ralegh tailor 370 00:18:40.519 --> 00:18:44.400 happens when fluids accelerate across a density boundary. Kelvin Helmholtz 371 00:18:44.440 --> 00:18:47.559 happens when fluids of different speeds move parallel to each 372 00:18:47.599 --> 00:18:51.799 other along a boundary. This creates intense shearing and mixing. 373 00:18:52.200 --> 00:18:55.559 The classic example is wind blowing across the surface of water. Right, 374 00:18:55.720 --> 00:18:56.640 it creates waves. 375 00:18:56.799 --> 00:18:59.920 Perfect example that share between the fast moving air and 376 00:19:00.119 --> 00:19:03.680 slower moving water creates waves which eventually break and mix 377 00:19:03.759 --> 00:19:06.440 the air and water together. It's a mixing instability. 378 00:19:06.799 --> 00:19:09.400 So in a typical full blown supernova, you get the 379 00:19:09.440 --> 00:19:13.480 initial RT fingers forming, but the extremely high velocities and 380 00:19:13.519 --> 00:19:17.839 the turbulent motions at the interface immediately cause cage instability 381 00:19:17.839 --> 00:19:18.359 to kick. 382 00:19:18.200 --> 00:19:23.240 In precisely, and cage instability just tears those RT fingers 383 00:19:23.279 --> 00:19:26.920 to shreds almost instantly. The material flows are so turbulent 384 00:19:26.960 --> 00:19:29.240 and they shear against each other with such violence that 385 00:19:29.680 --> 00:19:33.319 any structure is destroyed. That chaotic turbulent mixing is what 386 00:19:33.400 --> 00:19:37.759 makes standard supernova remnants look messy. That cauliflower shape is 387 00:19:37.759 --> 00:19:40.519 often a direct result of KH instability tearing up the 388 00:19:40.559 --> 00:19:41.880 initial RT structures. 389 00:19:42.319 --> 00:19:45.519 So chaos is the default state for a cosmic explosion. 390 00:19:45.680 --> 00:19:46.799 It is, which. 391 00:19:46.599 --> 00:19:49.759 Means that for Paianati to have this geometry, the cage 392 00:19:49.759 --> 00:19:53.440 instability must have been somehow suppressed or damped down. So 393 00:19:53.720 --> 00:19:55.519 how does a high density contrast do that. 394 00:19:55.680 --> 00:19:58.240 It's all about inertia. The wind that was launched by 395 00:19:58.240 --> 00:20:00.680 that surviving white dwarf was so much much heavier, so 396 00:20:00.759 --> 00:20:04.480 much denser than the surrounding interstellar gas that the mixing instability, 397 00:20:04.519 --> 00:20:07.079 the KH instability, just never got a chance to dominate, so. 398 00:20:07.000 --> 00:20:08.880 It couldn't get a grip. Basically, it couldn't. 399 00:20:09.000 --> 00:20:12.000 The source material notes that the density ratio between the 400 00:20:12.000 --> 00:20:14.759 ejecta from the star and the ambient medium around it 401 00:20:14.799 --> 00:20:16.400