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 Astronomi 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 --> 00:00:25.800 slumber under the night sky. 7 00:00:26.960 --> 00:00:29.679 We talk a lot on this deep dive about stars dying, 8 00:00:29.800 --> 00:00:33.479 which you know, sounds inherently dramatic. It does, but the 9 00:00:33.560 --> 00:00:37.159 universe doesn't really do simple melodrama. It deals in a 10 00:00:37.679 --> 00:00:42.159 complexity and just unimaginable violence exactly. And we're not just 11 00:00:42.200 --> 00:00:44.359 talking about a star dying here. We're talking about a 12 00:00:44.399 --> 00:00:49.320 whole category of cosmic events that well, that we may 13 00:00:49.359 --> 00:00:52.079 have been fundamentally misclassifying. 14 00:00:51.280 --> 00:00:53.759 For decades, or maybe a better way to put it 15 00:00:53.799 --> 00:00:57.399 is that the cosmos has just introduced a new hybrid 16 00:00:57.439 --> 00:00:58.920 category of extreme. 17 00:00:58.600 --> 00:01:00.560 Violence, a new category entirely. 18 00:01:00.679 --> 00:01:03.399 Yeah, we dove into a deep stack of sources all 19 00:01:03.439 --> 00:01:07.400 about this one cosmic event officially called at twenty twenty 20 00:01:07.439 --> 00:01:11.079 five oders, and this event, it, frankly, it acted like 21 00:01:11.079 --> 00:01:12.079 two different things at want. 22 00:01:12.040 --> 00:01:15.319 A massive star explosion, and a dead star merger. 23 00:01:15.040 --> 00:01:19.159 At the same time. It's presented astronomers with this really 24 00:01:19.159 --> 00:01:22.400 compelling paradox. It fundamentally challenges our rule book for how 25 00:01:22.439 --> 00:01:23.599 stars are supposed to die. 26 00:01:23.680 --> 00:01:25.480 So our mission today is to unpack. 27 00:01:25.200 --> 00:01:29.079 That it is. We're going to synthesize all this confusing 28 00:01:29.120 --> 00:01:31.959 contradictory data, the gravitational waves on one hand and the 29 00:01:32.000 --> 00:01:35.879 lightweights on the other, to understand the leading hypothesis, the 30 00:01:35.959 --> 00:01:38.719 birth of a brand new, first of its kind phenomenon 31 00:01:38.799 --> 00:01:40.640 called a super killinova. 32 00:01:41.079 --> 00:01:44.280 You know, I find it endlessly fascinating when the universe 33 00:01:44.359 --> 00:01:47.480 just throws out a plot twist, something that forces us 34 00:01:47.560 --> 00:01:49.439 to rewrite the physics textbooks. 35 00:01:49.560 --> 00:01:51.120 It happens more often than you'd think. 36 00:01:51.560 --> 00:01:54.079 But before we get there, we really need to quickly 37 00:01:54.120 --> 00:01:59.239 contextualize these cosmic blasts for you, because understanding the established difference, 38 00:01:59.599 --> 00:02:02.079 the different between the two main types of explosion is 39 00:02:02.159 --> 00:02:05.840 just crucial to grasping why eight twenty twenty five foals 40 00:02:06.200 --> 00:02:08.840 cause such an astronomical identity crisis. 41 00:02:09.039 --> 00:02:11.520 That's absolutely the right place to start. Think of it 42 00:02:11.599 --> 00:02:15.800 like this, stellar evolution has two massive endpoints, and each 43 00:02:15.840 --> 00:02:18.800 one is responsible for seating the universe with the basic 44 00:02:18.840 --> 00:02:21.879 chemistry that makes up well everything, including us. 45 00:02:22.000 --> 00:02:23.840 The first and probably the one people have heard of, 46 00:02:24.000 --> 00:02:24.800 is the supernova. 47 00:02:25.159 --> 00:02:28.840 Yes, this is the death of the behemoths. When the 48 00:02:28.840 --> 00:02:31.560 most massive stars, you know, the ones far bigger than 49 00:02:31.560 --> 00:02:37.159 our sun, burn through their fuel. They collapse violently, and 50 00:02:37.199 --> 00:02:38.599 then they explode. 51 00:02:38.120 --> 00:02:42.000 And that explosion seeds the universe with what exactly. 52 00:02:41.759 --> 00:02:44.680 Lighter heavy elements, so things like carbon, oxygen, nitrogen, all 53 00:02:44.719 --> 00:02:47.000 the way up the periodic table to iron. These are 54 00:02:47.039 --> 00:02:49.400 the elements that form the bulk of planets in life. 55 00:02:49.479 --> 00:02:52.199 They're essential, but they're kind of the common currency of 56 00:02:52.319 --> 00:02:54.800 stellar explosions. Yeah, it's a stellar collapse event. 57 00:02:54.960 --> 00:02:59.400 Okay, so if supernova are the common currency, killinova they're 58 00:02:59.439 --> 00:03:02.280 the mint. This is where the universe forges the really 59 00:03:02.439 --> 00:03:03.639 rare and fancy stuff. 60 00:03:03.680 --> 00:03:06.400 That's a great way to put it precisely. Killinova are 61 00:03:06.439 --> 00:03:09.280 fundamentally different. They aren't star deaths. They're dead star mergers. 62 00:03:09.400 --> 00:03:11.879 So not a collapse, a collision collision. 63 00:03:12.280 --> 00:03:17.080 It happens when two ultra dense, deceased stars, usually neutron stars, 64 00:03:17.319 --> 00:03:20.479 spiral into each other and just smash together at incredible speeds. 65 00:03:20.759 --> 00:03:23.039 And this is the only known environment in the universe 66 00:03:23.319 --> 00:03:26.680 where you get the right combination of insane heat density 67 00:03:27.000 --> 00:03:30.080 and a massive continuous flood of free neutrons. 68 00:03:29.639 --> 00:03:31.800 Which allows for something called our process. 69 00:03:31.400 --> 00:03:34.319 The rapid neutron capture process or our process yep. 70 00:03:34.479 --> 00:03:37.960 And why is that process so important for us here 71 00:03:38.000 --> 00:03:38.479 on Earth? 72 00:03:38.599 --> 00:03:42.680 Because our process is how the truly heaviest elements get forged. 73 00:03:43.280 --> 00:03:47.719 We're talking gold, platinum, uranium, the good stuff, all the 74 00:03:47.719 --> 00:03:51.120 precious metals, the radioactive components that are fundamental building blocks 75 00:03:51.159 --> 00:03:55.120 of planets. They are incredibly rare, born from these highly 76 00:03:55.199 --> 00:03:59.000 violent events and they're just astronomically significant. So when you 77 00:03:59.039 --> 00:04:01.199 find these elements here on Earth, you know that gold 78 00:04:01.240 --> 00:04:04.360 in your ring, it's the shrapnel from a Killinova that 79 00:04:04.400 --> 00:04:05.919 happened a long long time ago. 80 00:04:06.199 --> 00:04:09.360 The physics of the explosion dictates the chemistry of the universe. 81 00:04:09.400 --> 00:04:09.719 That's it. 82 00:04:09.960 --> 00:04:13.360 So to really appreciate just how strange at twenty twenty 83 00:04:13.360 --> 00:04:16.720 five Felatse was, we have to start with the baseline, 84 00:04:16.800 --> 00:04:19.560 the universally accepted gold standard Killinova. 85 00:04:19.079 --> 00:04:22.560 Which brings us to the blueprint of stellar collisions Killanova 86 00:04:22.639 --> 00:04:23.319 one oh one, And. 87 00:04:23.279 --> 00:04:24.879 There's one event that really stands out. 88 00:04:24.920 --> 00:04:27.720 The benchmark event absolutely, The one that proved the theory 89 00:04:27.759 --> 00:04:30.399 of Kelenova was GW one seven zero eight seventeen. That 90 00:04:30.480 --> 00:04:31.800 was back in August twenty seventeen. 91 00:04:31.879 --> 00:04:35.120 Before that, the idea was purely theoretical. 92 00:04:34.800 --> 00:04:38.560 Purely theoretical. The idea of two neutron stars merging and 93 00:04:38.600 --> 00:04:42.439 forging gold was just a model. This event was historic 94 00:04:42.720 --> 00:04:45.120 because it was the first and until our new friend 95 00:04:45.439 --> 00:04:48.560 at twenty twenty five latchers, yeah, the only time we 96 00:04:48.600 --> 00:04:52.920 had an unambiguously confirmed detection. It included both gravitational waves 97 00:04:52.920 --> 00:04:53.639 and light waves. 98 00:04:53.759 --> 00:04:56.759 That dual detection. Seeing the ripples in space time and 99 00:04:56.800 --> 00:04:57.160 then the. 100 00:04:57.079 --> 00:04:59.439 Flash of light, it changed astronomy forever. 101 00:04:59.560 --> 00:05:02.120 Okay, can we zero in on the gravitational wave part 102 00:05:02.160 --> 00:05:05.360 for a second. What exactly did those ripples in space 103 00:05:05.439 --> 00:05:08.360 time tell us about the objects before any telescopes even 104 00:05:08.360 --> 00:05:08.839 looked up? 105 00:05:09.040 --> 00:05:11.519 Right? So that's the real power of Ligo and Virgo, 106 00:05:11.959 --> 00:05:15.399 the detectors. They pick up this minute stretching and squeezing 107 00:05:15.399 --> 00:05:18.399 of space time. It's caused by the incredible acceleration of 108 00:05:18.439 --> 00:05:21.319 these neutron stars as they spiral into each other. It 109 00:05:21.480 --> 00:05:24.519 chirp signal, that's the one, and by analyzing the frequency 110 00:05:24.519 --> 00:05:27.480 in the amplitude of those incoming ripples, we can mathematically 111 00:05:27.480 --> 00:05:30.040 model the mass, the spin, even how far away the 112 00:05:30.040 --> 00:05:30.680 objects are. 113 00:05:30.800 --> 00:05:33.399 And for GW one seventy eight seventeen, what did that 114 00:05:33.519 --> 00:05:34.120 chirp say? 115 00:05:34.240 --> 00:05:37.399 The signal was clean, it was beautiful. It indicated the 116 00:05:37.439 --> 00:05:40.480 merger of two objects that were firmly in the expected 117 00:05:40.519 --> 00:05:44.519 mass range for neutron stars, somewhere between one point one 118 00:05:44.560 --> 00:05:46.759 and one point six times the mass of. 119 00:05:46.680 --> 00:05:49.879 Our sun, so perfectly normal neutron stars sextbook. 120 00:05:50.360 --> 00:05:53.920 And that initial signal immediately triggered an alert that went 121 00:05:53.959 --> 00:05:56.680 out to the world's optical telescopes, giving them a general 122 00:05:56.720 --> 00:05:58.199 direction in the sky to start looking. 123 00:05:58.360 --> 00:06:00.519 And what did they see? What was that unique visual 124 00:06:00.560 --> 00:06:03.720 fingerprint that confirmed, yes, this is the Kilanova the gravity 125 00:06:03.759 --> 00:06:04.639 waves told us about. 126 00:06:04.720 --> 00:06:07.279 They saw a rapid eruption of light. It peaked and 127 00:06:07.319 --> 00:06:10.000 then faded very very fast over a matter of days, 128 00:06:10.000 --> 00:06:14.120 maybe a week. And most importantly, it glowed this distinct 129 00:06:14.600 --> 00:06:16.240 deep crimson. 130 00:06:15.759 --> 00:06:18.959 Color red so quick and crimson that. 131 00:06:18.879 --> 00:06:21.560 Became the universal signature. If you're looking for a killinova, 132 00:06:21.759 --> 00:06:22.720 that's what you're looking for. 133 00:06:22.800 --> 00:06:24.839 And this is where we get to the really beautiful 134 00:06:24.920 --> 00:06:29.040 complex atomic chemistry. The color itself, the red color. The 135 00:06:29.079 --> 00:06:32.000 explosion is the smoking gun. It proves that gold and 136 00:06:32.120 --> 00:06:33.079 uranium are being made. 137 00:06:33.160 --> 00:06:34.560 It is this is the cool part. 138 00:06:34.720 --> 00:06:37.199 So walk us through the mechanism of that deep red glow. 139 00:06:37.319 --> 00:06:37.839 Why red. 140 00:06:37.959 --> 00:06:41.079 It's caused by something called the lanthanide curtain. So you 141 00:06:41.160 --> 00:06:44.040 have these extremely heavy elements being produced in the blast. 142 00:06:44.079 --> 00:06:48.639 Elements like the lanthanides, which include europium and of course gold, platinum, uranium. 143 00:06:48.839 --> 00:06:52.920 They all have these massive, really complex atomic nuclei, and 144 00:06:52.959 --> 00:06:56.639 that means that means they have a chaotic, dense arrangement 145 00:06:56.920 --> 00:06:58.279 of electron energy levels. 146 00:06:58.319 --> 00:07:01.120 Okay, so there are a lot more places for photons, 147 00:07:01.199 --> 00:07:03.839 for light particles to interact with the atom. 148 00:07:03.959 --> 00:07:06.600 Precisely, these elements, which are just churned out in the 149 00:07:06.639 --> 00:07:11.680 blast create this dense, opaque shell around the merger. So 150 00:07:11.759 --> 00:07:14.319 when light tries to pass through this cloud of newly 151 00:07:14.399 --> 00:07:19.319 minted heavy atoms, those complex electron structures are incredibly efficient 152 00:07:19.399 --> 00:07:22.519 at absorbing or blocking high energy photons. 153 00:07:22.079 --> 00:07:24.600 The blue light, the ultraviolet light exactly. 154 00:07:24.680 --> 00:07:27.120 Think of it like a very specific, very thick filter. 155 00:07:27.399 --> 00:07:30.000 The blue high energy light gets immediately trapped or scattered 156 00:07:30.000 --> 00:07:32.079 by the chaos of all these heavy elements. 157 00:07:31.680 --> 00:07:33.240 But the red light gets through. 158 00:07:33.480 --> 00:07:36.399 Exactly the lower energy light. The light at the red 159 00:07:36.439 --> 00:07:39.959 and infrared end of the spectrum is much less susceptible 160 00:07:40.000 --> 00:07:43.240 to this. It manages to pass through the dense debris 161 00:07:43.240 --> 00:07:47.160 cloud relatively unimpeded, So the light we end up observing 162 00:07:47.240 --> 00:07:51.000 is dramatically skewed toward those red wavelengths. 163 00:07:50.639 --> 00:07:54.480 Giving the Killinova its signature rapidly fading red. 164 00:07:54.199 --> 00:07:57.319 Glow and GW one seven zero eight seventeen established that 165 00:07:57.360 --> 00:08:01.240 perfectly dual detection rapid light curve and that telltale crimson 166 00:08:01.279 --> 00:08:05.040 color signaling that super heavy elements were being made. That 167 00:08:05.199 --> 00:08:07.079 is the classic established signature. 168 00:08:07.199 --> 00:08:09.800 Okay, let's just lay out that standard model one more time. 169 00:08:10.040 --> 00:08:12.639 GW one seven zero eight seventeen is the classic Killanova. 170 00:08:12.680 --> 00:08:14.399 You get the gravitational ways, you get the light, It 171 00:08:14.480 --> 00:08:17.160 fades fast, it glows red because of the heavy elements 172 00:08:17.199 --> 00:08:20.079 blocking the blue light. That's our perfect confirmed baseline. 173 00:08:20.120 --> 00:08:20.879 That's the blueprint. 174 00:08:21.079 --> 00:08:23.560 What happens when a new event looks exactly like that 175 00:08:23.680 --> 00:08:26.600 until the light curve takes a sudden, sharp and completely 176 00:08:26.639 --> 00:08:27.959 unexpected left turn. 177 00:08:27.879 --> 00:08:29.959 And that sudden turn brings us to the duel alert 178 00:08:30.759 --> 00:08:33.440 twenty twenty five sive arrest enters the scene. Because the 179 00:08:33.480 --> 00:08:36.240 initial observations, I mean they mirrored GW one seven zero 180 00:08:36.240 --> 00:08:40.480 eight seventeen almost perfectly. It gave astronomers this massive sense 181 00:08:40.519 --> 00:08:44.240 of deja vus. The countdown began on August eighteenth, twenty 182 00:08:44.279 --> 00:08:47.759 twenty five. That's when the gravitational wave trigger S two 183 00:08:47.840 --> 00:08:49.919 five zero eight eighteen K went off. 184 00:08:50.000 --> 00:08:52.360 Yeah, the alert went across the whole global network. The 185 00:08:52.399 --> 00:08:55.879 twin Lego detectors in the US, Virgo in Italy, and 186 00:08:55.960 --> 00:09:00.519 the whole international collaboration that includes Kjry and Japan. All 187 00:09:00.519 --> 00:09:02.000 of them picked up the signal. 188 00:09:01.720 --> 00:09:03.200 And they immediately sent out an. 189 00:09:03.120 --> 00:09:07.600 Alert immediately to the entire astronomical community saying, hey, a 190 00:09:07.639 --> 00:09:10.559 merger has occurred, and it's important to understand the scale 191 00:09:10.600 --> 00:09:13.320 of this. When an alert like this comes in, dozens 192 00:09:13.360 --> 00:09:16.639 of observatories large and small, they drop whatever they are doing. 193 00:09:16.720 --> 00:09:19.679 They re aim their telescopes and start scanning the sky 194 00:09:19.799 --> 00:09:20.840 region provided by the. 195 00:09:20.799 --> 00:09:23.080 Network because the window to catch the light is tiny. 196 00:09:23.320 --> 00:09:24.240 It's just a few days. 197 00:09:24.320 --> 00:09:27.240 But right from the start, the analysis of the gravitational 198 00:09:27.279 --> 00:09:30.960 wave data itself, it revealed something crucial that set this 199 00:09:31.000 --> 00:09:33.679 alert apart from GW one to seven AY eight seventeen. 200 00:09:34.080 --> 00:09:37.480 There was an immediate curiosity, maybe even a confusion about 201 00:09:37.480 --> 00:09:38.799 what was actually colliding. 202 00:09:39.120 --> 00:09:42.679 Yes, the signal was clearly a merger, no doubt about that, 203 00:09:43.399 --> 00:09:46.279 but the mathematical modeling of the waves indicated that at 204 00:09:46.360 --> 00:09:50.879 least one of the colliding objects was unusually tiny. The 205 00:09:50.919 --> 00:09:54.279 merger involved objects that were less massive than a typical 206 00:09:54.320 --> 00:09:54.960 neutron star. 207 00:09:55.320 --> 00:09:57.080 Specifically how tiny. 208 00:09:57.080 --> 00:09:59.600 Specifically, the data was consistent with at least one of 209 00:09:59.600 --> 00:10:03.039 the compon It's having a mass less than one solar mass. 210 00:10:02.759 --> 00:10:05.279 Wait, less massive than our own sun. 211 00:10:05.240 --> 00:10:10.000 Exactly subsolar mass. This immediately raised a giant red flag 212 00:10:10.600 --> 00:10:13.480 or maybe a beacon of interest for theorists. 213 00:10:13.120 --> 00:10:14.600 Because that's not supposed to happen. 214 00:10:14.759 --> 00:10:17.240 The standard lower limit for a stable neutron star is 215 00:10:17.240 --> 00:10:20.799 around one point two solar masses, so to detect a 216 00:10:20.840 --> 00:10:23.960 subsolar mass object in a merger, it meant we were 217 00:10:24.039 --> 00:10:27.320 potentially seeing something brand new about how stars evolve or 218 00:10:27.320 --> 00:10:28.480 how their remnants form. 219 00:10:28.679 --> 00:10:31.399 So even if the signal wasn't super strong right. 220 00:10:31.200 --> 00:10:33.639 As one of the LEGO team members noted, even if 221 00:10:33.639 --> 00:10:36.879 it wasn't the highest confidence alert ever, the truly intriguing 222 00:10:36.960 --> 00:10:39.600 nature of the objects that subsolar component. They got everyone's 223 00:10:39.600 --> 00:10:41.000 attention immediately, so. 224 00:10:40.960 --> 00:10:43.120 The gravity wave data gave them a rough map of 225 00:10:43.159 --> 00:10:45.919 where to look, which let the optical telescopes follow up 226 00:10:45.960 --> 00:10:47.039 incredibly fast. 227 00:10:47.120 --> 00:10:49.720 And that rapid response is just critical for catching these 228 00:10:49.720 --> 00:10:50.840 things before they disappear. 229 00:10:50.960 --> 00:10:54.000 And hours later, yeah, they found it. 230 00:10:54.120 --> 00:10:59.440 Hours later, This Wiki Transient Facility or ZTF at Palmar 231 00:10:59.440 --> 00:11:04.399 Observatory in California, they nailed the location. ZTF is basically 232 00:11:04.480 --> 00:11:07.919 designed for this kind of astronomical triosh. It scans huge 233 00:11:07.919 --> 00:11:11.399 areas of the sky really fast, looking for things to change, and. 234 00:11:11.320 --> 00:11:13.279 It found a rapidly fading red object. 235 00:11:13.360 --> 00:11:16.360 A rapidly fading red object about one point three billion 236 00:11:16.480 --> 00:11:19.399 light years away. It was initially tagged with a ZTF 237 00:11:19.519 --> 00:11:23.159 name and then later officially designated eight twenty twenty five flats. 238 00:11:23.360 --> 00:11:26.960 Location confirmed one point three billion light years away and 239 00:11:27.000 --> 00:11:30.279 the initial observations matched the Killanova blueprint perfectly. 240 00:11:30.440 --> 00:11:32.840 Absolutely did I mean this is where the initial belief 241 00:11:32.879 --> 00:11:36.120 that this was a standard Killanova really got cemented. About 242 00:11:36.159 --> 00:11:39.080 a dozen other telescopes jumped on it, cag and Hawaii, 243 00:11:39.159 --> 00:11:42.679 Wendelstein in Germany. The entire grouth network of observatories. They 244 00:11:42.679 --> 00:11:43.879 all pointed their mirrors at. 245 00:11:43.759 --> 00:11:45.480 The target and they all confirmed the same thing. 246 00:11:45.759 --> 00:11:49.519 They all confirmed it. The light eruption faded fast and 247 00:11:49.600 --> 00:11:52.080 it glowed at those signature red wavelengths. 248 00:11:52.200 --> 00:11:54.159 So, if you're an astronomer in those first few days, 249 00:11:54.200 --> 00:11:56.960 you're looking at a textbook Killinova. You've got the gravity 250 00:11:57.000 --> 00:11:59.559 waves from a merger. You've got the light signature confirming 251 00:11:59.600 --> 00:12:02.519 heavy elements being made, glowing red, fading fast. 252 00:12:02.559 --> 00:12:05.399 You're thinking, we've got it. This is the long awaited 253 00:12:05.639 --> 00:12:10.159 second confirmed Killinova, a perfect echo of GW one sever 254 00:12:10.240 --> 00:12:11.000 eight aii in. 255 00:12:11.360 --> 00:12:12.360 It was textbook. 256 00:12:12.519 --> 00:12:16.799 It was textbook until that initial fading curve bottomed out 257 00:12:16.919 --> 00:12:20.039 and then did something utterly inexplicable for a killinova. 258 00:12:20.080 --> 00:12:22.279 And this is where the paradox really sets in the 259 00:12:22.360 --> 00:12:26.919 astronomical identity crisis, because days after that initial blast, the 260 00:12:26.960 --> 00:12:31.320 textbook definition was just shattered at twenty twenty five years, 261 00:12:31.360 --> 00:12:32.840 completely changed its signature. 262 00:12:32.919 --> 00:12:36.639 The initial fast red phase was perfectly consistent with the Killanova, right, 263 00:12:36.840 --> 00:12:40.320 but then the event's characteristics just reversed entirely. The Killanova 264 00:12:40.320 --> 00:12:43.120 should only fade. That's the physics of it. The radioactive 265 00:12:43.159 --> 00:12:45.320 material dispersed it and it cools down quickly. 266 00:12:45.440 --> 00:12:48.159 But instead of continuing to fade, at twenty twenty five, 267 00:12:48.279 --> 00:12:49.720 chills started to brighten again. 268 00:12:50.000 --> 00:12:53.120 It did, and not only did the brightness reverse course, 269 00:12:53.600 --> 00:12:57.759 but the light changed color. It decisively turned blue. 270 00:12:57.840 --> 00:13:01.120 So if the red light signals heavy complex atoms and 271 00:13:01.120 --> 00:13:06.120 that lanthanide curtain, blue lights signal something completely different. 272 00:13:05.840 --> 00:13:10.360 Completely different, faster moving material, less obscured, higher energy, which 273 00:13:10.480 --> 00:13:11.720 usually means lighter. 274 00:13:11.399 --> 00:13:14.399 Element than the spectrum analysis delivered the biggest shock of all. 275 00:13:14.559 --> 00:13:17.600 The spectra began to show the unmistakable presence of hydrogen, 276 00:13:18.039 --> 00:13:21.159 and that is the observation that truly truly confounded everyone. 277 00:13:21.320 --> 00:13:24.039 It's the ultimate contradition to the Kilinova model. 278 00:13:24.159 --> 00:13:27.519 It is neutron star mergers happen after the original stars 279 00:13:27.519 --> 00:13:29.840 have stripped off their outer gas envelopes. Are just these 280 00:13:29.879 --> 00:13:33.840 extremely dense neutron rich objects. A Killinova should not be 281 00:13:33.879 --> 00:13:36.080 generating any significant detectable amount of. 282 00:13:36.120 --> 00:13:38.120 Hydrogen, because hydrogen is what stars are made of. 283 00:13:38.320 --> 00:13:41.159 Exactly so the presence of hydrogen, that color shift to blue, 284 00:13:41.600 --> 00:13:45.759 and the renewed brightening, all of those are classic undeniable 285 00:13:45.799 --> 00:13:50.559 signs of a core collapse. Supernova, specifically a stripped envelope type. 286 00:13:50.840 --> 00:13:53.159 So let me get this straight. We have a clear 287 00:13:53.200 --> 00:13:56.960 gravitational wave signal that says dead star merger, we have 288 00:13:57.000 --> 00:14:00.600 an initial light curve that says killin nova, but then 289 00:14:00.799 --> 00:14:03.759 we have a secondary light curve that screams supernova. 290 00:14:04.120 --> 00:14:08.159 That's the paradox, and it created immediate widespread controversy and 291 00:14:08.240 --> 00:14:11.200 deep skepticism in the wider astronomical community. 292 00:14:11.279 --> 00:14:14.200 And that skepticism was rooted in fundamental physics. 293 00:14:13.879 --> 00:14:17.960 Right it was. Supernova from distant galaxies are generally not 294 00:14:18.120 --> 00:14:22.360 expected to generate enough detectable gravitational waves for Lego and 295 00:14:22.440 --> 00:14:25.720 virgo to pick up. A supernova explosion is, for the 296 00:14:25.759 --> 00:14:29.320 most part symmetric. The ways it produces tend to cancel 297 00:14:29.360 --> 00:14:29.919 each other out. 298 00:14:30.039 --> 00:14:32.080 But killinova mergers are the opposite. 299 00:14:32.120 --> 00:14:35.960 They're highly asymmetric and incredibly violent. They produce a very strong, 300 00:14:36.120 --> 00:14:38.279 very measurable gravitational wave signal. 301 00:14:38.440 --> 00:14:41.159 So if the optical signal turned out to be a supernova, 302 00:14:41.200 --> 00:14:44.600 the simplest explanation was that the two events were just unrelated. 303 00:14:44.759 --> 00:14:46.960 That eighteen to twenty twenty five full Is was just 304 00:14:47.000 --> 00:14:49.879 a typical ho hum supernova that happened to be in 305 00:14:49.919 --> 00:14:52.399 the same part of the sky as the gravitational wave signal. 306 00:14:52.480 --> 00:14:55.159 That's right, and based on the source material, this is 307 00:14:55.200 --> 00:14:57.519 precisely where many astronomers just lost interest. 308 00:14:57.879 --> 00:15:00.960 They just wrote it off as a coincidence herring they did. 309 00:15:01.240 --> 00:15:04.519 They concluded the initial killinova alert was a bust, that 310 00:15:04.559 --> 00:15:08.120 it was unrelated to the later optical brightening. They assumed 311 00:15:08.240 --> 00:15:12.600 the gravitational wave alert came from some invisible dark merger 312 00:15:12.639 --> 00:15:15.000 event and the supernova just happened to be nearby. 313 00:15:15.480 --> 00:15:17.440 But what about the odds of that, I mean, a 314 00:15:17.559 --> 00:15:22.960 distant supernova coincidentally appearing in the same gravitational wave map location. 315 00:15:23.960 --> 00:15:26.399 That has to be pretty low, right, How did the 316 00:15:26.399 --> 00:15:28.039 Celtech team argue against that? 317 00:15:28.360 --> 00:15:30.799 The probability of a chance alignment like that is low, 318 00:15:30.840 --> 00:15:33.200 you know, maybe one in one hundred thousand, but it's 319 00:15:33.240 --> 00:15:37.320 not astronomically impossible. Those gravitational wave mapping boxes are still 320 00:15:37.320 --> 00:15:39.879 pretty large areas of the sky. The issue was less 321 00:15:39.919 --> 00:15:42.320 about pure probability and more about Ockham's razor. 322 00:15:42.639 --> 00:15:44.360 The simplest explanation is usually the. 323 00:15:44.360 --> 00:15:48.480 Correct one, Right, A merger produces gravitational waves, a supernova 324 00:15:48.519 --> 00:15:52.159 produces light. If the light signal later looks unambiguously like 325 00:15:52.200 --> 00:15:54.759 a supernova. You just separate the two events. 326 00:15:55.000 --> 00:15:58.399 But the team, led by Caltech's Mancy Cosliwall she's the 327 00:15:58.480 --> 00:16:01.120 lead author of the key study, they insisted that something 328 00:16:01.200 --> 00:16:04.399 unusual was happening. They refused to just dismiss the connection. 329 00:16:04.519 --> 00:16:08.240 And their perseverance was based on this really deep, critical 330 00:16:08.279 --> 00:16:11.960 analysis of the data. They noted that the event it 331 00:16:11.960 --> 00:16:14.480 didn't look like an average supernova either. It was an 332 00:16:14.480 --> 00:16:17.960 odd ball as soon it had the unprecedented speed and 333 00:16:18.000 --> 00:16:21.120 the initial red phase of a killinova, but that was 334 00:16:21.200 --> 00:16:25.559 overlaid with the later powerful characteristics of a supernova. They 335 00:16:25.559 --> 00:16:28.960 saw that unusual dual phase light signature as evidence of 336 00:16:28.960 --> 00:16:30.840 a connection, not a coincidence. 337 00:16:31.159 --> 00:16:33.480 So the very fact that it didn't fit neatly into 338 00:16:33.519 --> 00:16:36.919 either category, not a classic killanova, not a classic supernova, 339 00:16:37.240 --> 00:16:39.879 that's what kept them pursuing it. The messiness of the 340 00:16:39.960 --> 00:16:42.080 data itself became the clue. 341 00:16:41.759 --> 00:16:45.120 Exactly, and that critical insight brings us to the hypothesis 342 00:16:45.159 --> 00:16:48.320 of the super killinova. This provides a framework for how 343 00:16:48.399 --> 00:16:51.480 one single cosmic event could execute a two part explosion, 344 00:16:51.720 --> 00:16:55.240 producing both that immediate merger signal and the later obscuring 345 00:16:55.480 --> 00:16:57.080 supernova signature. 346 00:16:56.799 --> 00:16:59.879 A killinova spurred on by a supernova. That's the idea 347 00:17:00.039 --> 00:17:02.519 and the core argument for the super kilinova hinges on 348 00:17:02.600 --> 00:17:06.279 connecting those two extremely strange clues that defy the standard models. 349 00:17:06.920 --> 00:17:09.000 The first one which we touched on is the nature 350 00:17:09.039 --> 00:17:10.640 of the colliding objects themselves. 351 00:17:10.920 --> 00:17:14.240 That's the lynchpin. The Lygovirgo data showed that at least 352 00:17:14.279 --> 00:17:17.599 one object in the merger was less massive than a 353 00:17:17.640 --> 00:17:22.240 typical neutron star, a subsolar mass neutron star. And this 354 00:17:22.279 --> 00:17:24.920 is the concept of the forbidden mass range, and it's 355 00:17:24.960 --> 00:17:27.599 a huge challenge to standard stellar physics. 356 00:17:27.799 --> 00:17:30.480 So why is that mass range, you know, less than 357 00:17:30.519 --> 00:17:35.400 one point two solar masses considered forbidden or so problematic 358 00:17:35.480 --> 00:17:36.880 for a stable neutron star. 359 00:17:37.160 --> 00:17:38.880 Okay, so we have to go back to the fundamental 360 00:17:38.880 --> 00:17:42.880 physics of extreme density. When a massive star dies, gravity 361 00:17:42.920 --> 00:17:45.960 collapses the core until the matter is so dense that 362 00:17:46.000 --> 00:17:49.480 electrons and protons are literally crushed together into neutrons. 363 00:17:49.640 --> 00:17:52.400 And it's the pressure from those neutrons that stops the collapse. 364 00:17:52.519 --> 00:17:55.599 Yes, it's called neutron degeneracy pressure. It's the quantum pressure 365 00:17:55.640 --> 00:17:58.440 from these tightly packed neutrons that halts the collapse and 366 00:17:58.519 --> 00:18:01.160 stabilizes the star forms a neutron star. 367 00:18:01.279 --> 00:18:04.000 It's basically the last line of defense against becoming a black. 368 00:18:03.799 --> 00:18:07.319 Hole, precisely, and to overcome the outward push of that 369 00:18:07.440 --> 00:18:11.000 pressure and stabilize the star, you need a critical amount 370 00:18:11.039 --> 00:18:15.400 of mass, and theoretical models, which have been corroborated by 371 00:18:15.440 --> 00:18:19.400 decades of observation, plays that lower limit. The minimum mass 372 00:18:19.440 --> 00:18:22.279 you need at around one point two times the mass. 373 00:18:22.079 --> 00:18:24.079 Of our Sun, and anything smaller than that. 374 00:18:24.240 --> 00:18:28.000 Anything smaller, according to standard models, just can't sustain the 375 00:18:28.000 --> 00:18:30.799 neutron star structure. It would either bounce back and never 376 00:18:30.839 --> 00:18:33.960 fully collapse, or it would form something far less dense, 377 00:18:34.039 --> 00:18:34.839 like a white dwarf. 378 00:18:35.319 --> 00:18:38.039 So if the gravitational wave signature is telling us that 379 00:18:38.079 --> 00:18:41.359 at least one of these colliding objects was significantly smaller 380 00:18:41.400 --> 00:18:44.680 than one point two solar masses, then the way that 381 00:18:44.720 --> 00:18:47.559 object was formed must have been fundamentally different from the 382 00:18:47.559 --> 00:18:48.359 standard model. 383 00:18:48.400 --> 00:18:52.160 That's the only logical conclusion. And theorists, including Brian Metzger 384 00:18:52.160 --> 00:18:55.599 at Columbia, had previously proposed ways for these tiny objects 385 00:18:55.599 --> 00:18:59.359 to exist, but they had never been observed before. They 386 00:18:59.359 --> 00:19:03.279 are the essenti missing piece of this whole superkillinova theory. 387 00:19:03.200 --> 00:19:05.279 We need a way to explain how the universe Strea 388 00:19:07.960 --> 00:19:11.519 so Metzker's team proposed two theoretical scenarios for how these 389 00:19:11.880 --> 00:19:16.480 subsolar neutron stars could be formed during a supernova. Let's 390 00:19:16.480 --> 00:19:19.759 start with the first one, fission, the idea of splitting 391 00:19:19.759 --> 00:19:20.279 the core. 392 00:19:20.680 --> 00:19:23.359 Okay, so in the fission scenario, you start with an 393 00:19:23.440 --> 00:19:27.440 incredibly massive star that is spinning extremely rapidly as it 394 00:19:27.480 --> 00:19:30.839 collapses and goes supernova. That rotation is key. 395 00:19:30.920 --> 00:19:31.799 It's all about the spin. 396 00:19:31.960 --> 00:19:34.759 It's all about the spin. Instead of the core collapsing 397 00:19:34.839 --> 00:19:39.599 neatly into one single remnant, the extreme centripetal forces, coupled 398 00:19:39.599 --> 00:19:42.920 with the instability of the core, cause the collapsing matter 399 00:19:43.000 --> 00:19:48.240 to split or fission into two tiny, separate subsolar mass 400 00:19:48.359 --> 00:19:49.240 neutron stars. 401 00:19:49.359 --> 00:19:51.839