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 --> 00:00:23.800 slumber under the night sky. 7 00:00:26.879 --> 00:00:30.440 Okay, let's unpack this. We often frame the universe as 8 00:00:30.679 --> 00:00:35.200 you know, this enormous, immutable backdrop, something so ancient and 9 00:00:35.320 --> 00:00:37.920 vast that it seems entirely static over the span of 10 00:00:37.960 --> 00:00:42.399 a human lifetime. We look up and the stars they're 11 00:00:42.439 --> 00:00:44.880 pretty much where they were for our great grandparents, right. 12 00:00:44.880 --> 00:00:47.799 Right, that's the common perception, fixed, unchanging. 13 00:00:47.920 --> 00:00:50.679 But today we're diving into the study of a single 14 00:00:50.759 --> 00:00:55.039 object that well violently defies that expectation, an object whose 15 00:00:55.119 --> 00:00:58.560 changes are so rapid they can actually be measured, tracked, 16 00:00:58.640 --> 00:01:01.039 observed over just a hie hundred and thirty years. 17 00:01:01.119 --> 00:01:05.480 And it's those dramatic visible shifts, these objects evolving within 18 00:01:05.560 --> 00:01:09.760 our are observational record that really force us to challenge 19 00:01:09.799 --> 00:01:13.159 those underlying assumptions we think of stellar evolution in millions 20 00:01:13.200 --> 00:01:15.760 billions of years. Now here we have a real time lab, 21 00:01:15.879 --> 00:01:17.640 relatively speaking, showing change over. 22 00:01:17.519 --> 00:01:20.040 A single century exactly. We are looking at the stunning 23 00:01:20.120 --> 00:01:23.760 planetary nebula, known officially as IC four eighteen, but you 24 00:01:23.760 --> 00:01:26.719 probably know it better by its nickname, the spirograph nebula. 25 00:01:26.760 --> 00:01:28.719 Ah. Yes, the spirograph. It's a great name. 26 00:01:28.840 --> 00:01:33.159 Name for those complex, intricate looping structures. The Hubble space 27 00:01:33.200 --> 00:01:37.079 telescope captured so beautifully. It really does look like something 28 00:01:37.120 --> 00:01:38.719 made with that old geometric toy. 29 00:01:38.920 --> 00:01:41.920 And that nickname is important. I think it grounds the 30 00:01:41.959 --> 00:01:46.879 science and something well familiar and beautiful. It emphasizes this 31 00:01:46.920 --> 00:01:51.560 isn't just some distant, fuzzy smudge. It's dynamic caught right 32 00:01:51.599 --> 00:01:54.000 in the act of its final transformation. 33 00:01:53.560 --> 00:01:57.519 Cosmic change on a timescale we can actually grasp precisely. 34 00:01:57.719 --> 00:02:00.599 So our mission today is built around this fascinating study 35 00:02:00.640 --> 00:02:05.480 publish in Astrophysical Journal Letters. The team accomplished something pretty remarkable. 36 00:02:05.879 --> 00:02:09.159 They stitch together this almost unbroken one hundred and thirty 37 00:02:09.240 --> 00:02:11.719 year lineage of observations for Icy. 38 00:02:11.599 --> 00:02:13.400 Four eighteen, a huge undertaking. 39 00:02:13.520 --> 00:02:15.520 They did this to track the star's death rows, and 40 00:02:15.599 --> 00:02:19.840 specifically to figure out what it's well, astonishingly rapid evolution 41 00:02:20.039 --> 00:02:22.879 means for a really fundamental question, which is how the 42 00:02:23.039 --> 00:02:27.319 ingredients for life, particularly carbon, get distributed throughout the galaxy. 43 00:02:27.520 --> 00:02:30.039 Ah, the big one, cosmic chemistry. So it's like a 44 00:02:30.080 --> 00:02:32.719 detective story starting way back in the nineteenth century and. 45 00:02:32.800 --> 00:02:35.759 Ending with some pretty profound implications for how we understand 46 00:02:35.840 --> 00:02:36.840 astrophysics today. 47 00:02:37.120 --> 00:02:37.639 Exactly. 48 00:02:37.719 --> 00:02:40.520 Okay, so let's start with the basics. The object itself 49 00:02:40.840 --> 00:02:43.039 IC four eighteen. Where do we find it? 50 00:02:43.199 --> 00:02:46.879 Right? You need to look towards the southern constellation Lepis. 51 00:02:47.159 --> 00:02:52.520 That's Latin for the hair. It's situated about two thousand 52 00:02:52.560 --> 00:02:53.479 light years away from US. 53 00:02:53.479 --> 00:02:57.319 Two thousand light years, so relatively close in galactic terms, 54 00:02:57.360 --> 00:02:58.439 but still a long way off. 55 00:02:58.560 --> 00:03:02.000 Oh absolutely. And physically it spans roughly zero point two 56 00:03:02.080 --> 00:03:03.400 light years across. 57 00:03:03.199 --> 00:03:04.840 Which sounds small maybe, but. 58 00:03:04.840 --> 00:03:07.800 That's well, it's about twelve trillion miles give or take, 59 00:03:08.000 --> 00:03:09.240 so not insignificant. 60 00:03:09.319 --> 00:03:11.319 Okay, yeah, definitely not small, but from. 61 00:03:11.240 --> 00:03:14.520 Earth its apparent size is quite compact. It shines at 62 00:03:14.520 --> 00:03:15.919 about magnitude plus nine. 63 00:03:15.960 --> 00:03:17.879 I mean you'd need a telescope. 64 00:03:17.400 --> 00:03:20.439 Oh yes, definitely not naked eye, and it appears about 65 00:03:20.439 --> 00:03:24.319 eighteen arc seconds across in the sky, think roughly the 66 00:03:24.360 --> 00:03:26.919 size of Jupiter through a decent backyard telescope when it's 67 00:03:26.919 --> 00:03:28.159 looking particularly large. 68 00:03:28.360 --> 00:03:30.680 Got it. Now we have to pause in the name 69 00:03:30.759 --> 00:03:35.759 planetary nebula. It's famously confusing, right, because they have absolutely 70 00:03:35.759 --> 00:03:37.919 nothing to do with planets. 71 00:03:37.199 --> 00:03:40.159 Nothing at all. To one of those historical quirks, the 72 00:03:40.240 --> 00:03:43.360 name stuck from when astronomers like William Herschel first saw 73 00:03:43.360 --> 00:03:48.039 them through their early, less powerful telescopes. These objects look 74 00:03:48.199 --> 00:03:51.879 like round, ghostly discs, kind of like the faint appearance 75 00:03:51.919 --> 00:03:53.759 of Urinus or Neptune. 76 00:03:53.439 --> 00:03:54.879 The known planets at the time. 77 00:03:55.080 --> 00:03:57.800 Exactly. They didn't have the resolution to see the structure, 78 00:03:57.879 --> 00:04:01.560 just these fuzzy planet like shapes, So the name stuck 79 00:04:01.800 --> 00:04:02.759 planetary nebula. 80 00:04:02.919 --> 00:04:07.039 But they're actually the uh, spectacular final breaths of a star, 81 00:04:07.080 --> 00:04:07.520 aren't they. 82 00:04:07.599 --> 00:04:10.199 That's right. It happens when a star similar to our Sun, 83 00:04:10.280 --> 00:04:13.520 runs out of fuel, expands hugely into a red giant, 84 00:04:13.719 --> 00:04:15.080 and then puffs off as outer. 85 00:04:14.960 --> 00:04:17.160 Layers, creating that glowing shell we see. 86 00:04:18.120 --> 00:04:19.959 And for us, the real hook and the reason we 87 00:04:20.000 --> 00:04:21.680 have this one hundred and thirty year timeline is the 88 00:04:21.759 --> 00:04:23.319 human story behind its discovery. 89 00:04:23.360 --> 00:04:24.879 This is where Williamina Fleming comes in. 90 00:04:25.040 --> 00:04:27.920 Yes, the discovery back on March twenty six, eighteen ninety 91 00:04:27.920 --> 00:04:31.000 one belongs squarely to her. She was a true pioneer 92 00:04:31.120 --> 00:04:33.720 of well modern data driven astronomy. 93 00:04:33.839 --> 00:04:36.399 She was a Scottish American working at the Harvard College 94 00:04:36.439 --> 00:04:41.360 Observatory HCO, part of that massive Draper catalog survey. And 95 00:04:41.399 --> 00:04:43.319 you really have to picture her work right. She wasn't 96 00:04:43.319 --> 00:04:45.079 at a telescope eyepiece. 97 00:04:44.800 --> 00:04:49.199 No, not usually. She was in a room meticulously painstakingly 98 00:04:49.680 --> 00:04:55.160 examining thousands upon thousands of photographic glass plates, huge heavy things. 99 00:04:55.120 --> 00:04:58.160 Like the world's first large scale scientific data analyst. 100 00:04:58.319 --> 00:05:02.360 Essentially, you could definitely say that grueling work. Those plates 101 00:05:02.399 --> 00:05:06.120 required expert interpretation. Her role and that of the other 102 00:05:06.160 --> 00:05:09.800 women known as the Harvard Computers was crucial. They classified 103 00:05:09.839 --> 00:05:12.680 stars based on their spectra, the patterns in their light, 104 00:05:12.920 --> 00:05:15.240 and spotted anything unusual like a nebula. 105 00:05:15.319 --> 00:05:18.199 And she was incredibly prolific. The notes mentioned she discovered 106 00:05:18.240 --> 00:05:21.120 fifty nine nebulae just during her work on that one survey. 107 00:05:21.319 --> 00:05:24.920 Fifty nine imagine IC four eighteen was just one entry 108 00:05:24.920 --> 00:05:27.240 in a huge body of work. She was instrumental in 109 00:05:27.279 --> 00:05:31.519 shifting astronomy from just describing things to systematically classifying them 110 00:05:31.680 --> 00:05:33.360 based on physics derived from light. 111 00:05:33.600 --> 00:05:36.199 Her observation in eighteen ninety one is the absolute starting 112 00:05:36.240 --> 00:05:38.920 point for this whole study we're discussing the anchor. 113 00:05:39.279 --> 00:05:42.120 Without her and the rigorous record keeping at Harvard, we 114 00:05:42.120 --> 00:05:45.199 wouldn't have this baseline. We couldn't track this evolution. 115 00:05:45.519 --> 00:05:48.519 And just a quick historical note, although it was later 116 00:05:48.560 --> 00:05:52.480 cataloged as IC four eighteen and sometimes misattributed, the initial 117 00:05:52.519 --> 00:05:56.600 credit belongs to Fleming eighteen ninety one. That's our starting gun. 118 00:05:56.759 --> 00:05:57.600 Absolutely key. 119 00:05:57.720 --> 00:05:59.600 Okay, this is where it gets really interesting. I think 120 00:05:59.759 --> 00:06:05.480 we move from historical discovery to like modern scientific detective work. 121 00:06:05.800 --> 00:06:08.439 You've got this object observed in the eighteen nineties. How 122 00:06:08.480 --> 00:06:12.759 on earth do researchers today track its physical evolution? How 123 00:06:12.800 --> 00:06:14.920 do they bridge one hundred and thirty years of completely 124 00:06:14.920 --> 00:06:15.759 different technology. 125 00:06:15.839 --> 00:06:19.000 Yeah, that's the challenge, going from someone literally describing what they. 126 00:06:18.839 --> 00:06:23.600 Saw right to photographic plates to modern digital cameras. 127 00:06:23.319 --> 00:06:25.519 Like the Hubble Space telescope. It's what we might call 128 00:06:26.000 --> 00:06:27.199 forensic astronomy. 129 00:06:27.319 --> 00:06:28.319 Forensic astronomy. 130 00:06:28.319 --> 00:06:31.240 I like that, and IC four eighteen had a unique advantage. 131 00:06:31.399 --> 00:06:35.480 It has this almost unbroken chain of spectroscopic measurements. 132 00:06:35.600 --> 00:06:37.399 Spectroscopy breaking down the light. 133 00:06:37.600 --> 00:06:41.560 Exactly, breaking light into its component wavelengths like a rainbow 134 00:06:41.800 --> 00:06:45.639 to figure out temperature, speed, chemical makeup. That technique was 135 00:06:45.759 --> 00:06:48.480 just getting started in the eighteen nineties, and ICE four 136 00:06:48.519 --> 00:06:49.879 eighteen was an early target. 137 00:06:49.959 --> 00:06:54.199 So they were pulling data from completely different eras visual observations, 138 00:06:54.199 --> 00:06:57.879 glass plates, film, digital CCDs. 139 00:06:58.399 --> 00:07:03.000 Three distinct technology phases. And the trick is making sure 140 00:07:03.000 --> 00:07:05.720 that data from all these sources well speaks the same 141 00:07:05.800 --> 00:07:07.720 language can be reliably compared. 142 00:07:08.120 --> 00:07:11.759 How do you even use data from say, eighteen ninety three? 143 00:07:12.279 --> 00:07:15.439 You mentioned William Campbell observed a spectrum, then how is 144 00:07:15.480 --> 00:07:17.000 a visual description useful? 145 00:07:17.199 --> 00:07:20.319 It sounds imprecise, doesn't it, Hugh? But the key is 146 00:07:20.360 --> 00:07:24.480 that earliest drimers, even without digital tools, were incredibly meticulous 147 00:07:24.519 --> 00:07:27.759 note takers. Doctor Albert Zealstra, one of the researchers on 148 00:07:27.800 --> 00:07:31.639 this recent study, pointed out that Campbell's observation was described. 149 00:07:31.199 --> 00:07:33.240 Well enough, well enough for what though. 150 00:07:33.040 --> 00:07:35.600 Well enough to establish a baseline. He described the visible 151 00:07:35.600 --> 00:07:39.360 emission lines crucially their brightness relative to other known lines 152 00:07:39.480 --> 00:07:42.360 like hydrogen. That relative brightness gives you a starting point 153 00:07:42.480 --> 00:07:44.680 even if it's not a precise number like we get today. 154 00:07:44.879 --> 00:07:48.920 So it's the relative information that matters. That's amazing trusting 155 00:07:48.959 --> 00:07:51.079 those one hundred and forty year old notes. 156 00:07:51.160 --> 00:07:53.040 It's a testament to their standards. They knew they were 157 00:07:53.040 --> 00:07:54.639 recording something important. 158 00:07:54.439 --> 00:07:56.720 But the jump to photographic plates must have been a 159 00:07:56.800 --> 00:07:59.519 huge challenge correcting for the technology itself. 160 00:07:59.600 --> 00:08:02.399 That's where the forensic part really kicks in. You have 161 00:08:02.480 --> 00:08:06.519 to account for technological bias. An old glass plate doesn't 162 00:08:06.519 --> 00:08:10.680 record light linearly. The brightness depends entirely on the chemical 163 00:08:10.759 --> 00:08:12.920 emulsion used on that specific plate. 164 00:08:13.079 --> 00:08:17.480 Ah okay, so different plates from different times might be 165 00:08:17.600 --> 00:08:20.439 more sensitive to blue light or less sensitive to. 166 00:08:20.399 --> 00:08:23.560 Red precisely, and a researcher today needs to know that 167 00:08:23.639 --> 00:08:27.839 specific sensitivity profile to figure out the star's actual energy 168 00:08:27.839 --> 00:08:29.839 output at different wavelengths back then. 169 00:08:30.399 --> 00:08:34.639 So they have to mathematically reconstruct what the chemical properties 170 00:08:34.679 --> 00:08:36.279 of old photo emulsions. 171 00:08:36.360 --> 00:08:40.480 Essentially, yes, they model the sensitivity curves of those historical chemicals. 172 00:08:40.480 --> 00:08:43.840 They look at old lab notes, log books about atmosphere conditions, 173 00:08:44.039 --> 00:08:47.200 even the type of silver halide used. It's about converting 174 00:08:47.240 --> 00:08:49.759 a recorded density on the plate back into a physically 175 00:08:49.799 --> 00:08:51.039 meaningful footon count. 176 00:08:51.200 --> 00:08:55.759 That is incredibly detailed work. You're part historian, part chemist, 177 00:08:55.840 --> 00:08:57.120 part astrophysicist. 178 00:08:57.320 --> 00:09:00.279 It takes a team with diverse skills, definitely, but it's 179 00:09:00.360 --> 00:09:02.879 crucial to make sure the eighteen ninety three data is 180 00:09:02.960 --> 00:09:07.039 genuinely comparable to Hubble data from say twenty eighteen. The 181 00:09:07.080 --> 00:09:08.639 whole study hangs on getting that right. 182 00:09:08.679 --> 00:09:11.879 And they focused on specific emission lines. You said hydrogen 183 00:09:12.000 --> 00:09:15.360 and this doubly ionized oxygen OII. 184 00:09:15.679 --> 00:09:18.440 Yes, those were key, especially the OII lines in the 185 00:09:18.440 --> 00:09:20.919 blue green part of the spectrum, and that can expect 186 00:09:20.960 --> 00:09:24.559 perfectly to another historical quirk, the nebulium mystery. 187 00:09:24.759 --> 00:09:28.000 Ah right, the element that never was exactly. 188 00:09:28.039 --> 00:09:31.440 Back in the late nineteenth early twentieth century, astronomers kept 189 00:09:31.440 --> 00:09:35.200 seeing these really bright, distinct emission lines in nebulae spectra. 190 00:09:35.600 --> 00:09:37.679 Lines they couldn't match to any element known on. 191 00:09:37.559 --> 00:09:39.799 Earth, so naturally they assumed. 192 00:09:39.480 --> 00:09:41.320 It must be a new element. They even gave it 193 00:09:41.360 --> 00:09:44.399 a name, nebulium. It was a big puzzle, why couldn't 194 00:09:44.399 --> 00:09:45.200 they recreate it in the. 195 00:09:45.240 --> 00:09:47.240 Lab until physics caught up right. 196 00:09:47.600 --> 00:09:50.559 It wasn't until the nineteen twenties, with advances in atomic 197 00:09:50.559 --> 00:09:53.039 physics that Ira Bowen figured it out. It wasn't a 198 00:09:53.080 --> 00:09:53.919 new element at all. 199 00:09:54.000 --> 00:09:56.559 It was just familiar elements acting weirdly. 200 00:09:56.559 --> 00:10:00.159 Exactly common stuff like oxygen and nitrogen. But what are 201 00:10:00.200 --> 00:10:05.679 the incredibly extreme conditions inside a nebula? Specifically ultraload density 202 00:10:05.720 --> 00:10:09.879 and intense radiation. These atoms can emit light in ways 203 00:10:10.000 --> 00:10:13.320 through forbidden transitions that are basically impossible to achieve in 204 00:10:13.360 --> 00:10:14.759 a dense Earth atmosphere. 205 00:10:14.799 --> 00:10:17.519 So the light they called nebulium was actually just ionized 206 00:10:17.559 --> 00:10:20.279 oxygen behaving strangely because of the nebula's. 207 00:10:19.879 --> 00:10:23.279 Environment precisely and the way those oxygen atoms emit that 208 00:10:23.360 --> 00:10:27.000 specific light. The former nebulium signature turns out to be 209 00:10:27.200 --> 00:10:30.559 extremely sensitive to the temperature and density of the nebula gas. 210 00:10:30.759 --> 00:10:34.200 Oh so tracking those specific lines over one hundred and 211 00:10:34.200 --> 00:10:37.440 thirty years lets them track how the physical conditions inside 212 00:10:37.480 --> 00:10:38.639 the nebula have changed. 213 00:10:38.720 --> 00:10:41.600 That's the key. They started out chasing a fictional element 214 00:10:41.799 --> 00:10:44.360 and ended up using that very same light signature to 215 00:10:44.399 --> 00:10:47.399 measure one of the fastest stellar temperature changes ever recorded. 216 00:10:47.600 --> 00:10:52.159 Incredible, the science evolving alongside the observation. Okay, let's get 217 00:10:52.200 --> 00:10:55.000 to the core discovery, the numbers that really made the 218 00:10:55.000 --> 00:10:58.559 astronomical community sit up and take notice. But first, maybe 219 00:10:58.559 --> 00:11:00.919 just quickly remind us what's our actually happening when a 220 00:11:00.960 --> 00:11:03.159 star like this dies? What are the death throws? 221 00:11:03.440 --> 00:11:07.080 Right? It's a dramatic, but in a way beautiful process. 222 00:11:07.480 --> 00:11:10.960 It starts when a star roughly like our Sun, exhausts 223 00:11:10.960 --> 00:11:14.360 the hydrogen fuel in its core. Gravity causes the core 224 00:11:14.399 --> 00:11:17.399 to contract and heat up while the outer layers swell enormously. 225 00:11:17.440 --> 00:11:18.480 It becomes a red. 226 00:11:18.279 --> 00:11:21.639 Giant, sometimes swallowing its inner planets potentially yes. 227 00:11:22.360 --> 00:11:26.279 Then, over a relatively short period aftronomically speaking, it sheds 228 00:11:26.279 --> 00:11:30.000 those bloated outer layers into space. That expelled gas and 229 00:11:30.120 --> 00:11:34.240 dust forms the expanding glowing shell, the planetary nebula like 230 00:11:34.519 --> 00:11:35.120 IC four. 231 00:11:34.960 --> 00:11:37.000 Eighteen, and what's left behind in the center. 232 00:11:36.960 --> 00:11:40.679 The incredibly dense hot core of the former star. It 233 00:11:40.720 --> 00:11:43.360 collapses down into what we call a white dwarf. Think 234 00:11:43.399 --> 00:11:45.600 of it as a stellar ember, compressed to about the 235 00:11:45.639 --> 00:11:48.320 size of Earth, but still containing maybe sixty percent of 236 00:11:48.360 --> 00:11:51.279 the star's original mass. In IC four eighteen's case, it's 237 00:11:51.320 --> 00:11:53.480 about zero point six times the Sun's. 238 00:11:53.159 --> 00:11:56.600 Mass, just glowing incredibly hot from left over heat exactly. 239 00:11:56.840 --> 00:11:59.120 And this whole process, this is the fate awaiting our 240 00:11:59.159 --> 00:12:02.679 own Sun and the Solar system in about five billion years. 241 00:12:03.159 --> 00:12:06.159 Right, So IC four eighteen is showing us our future 242 00:12:06.480 --> 00:12:06.759 in a. 243 00:12:06.679 --> 00:12:09.440 Way, in a very real way. Now, normally, the changes 244 00:12:09.480 --> 00:12:12.679 in the star's temperature, especially during these later stages, happen 245 00:12:12.759 --> 00:12:17.080 over incredibly long time scales millennia, millions of years. 246 00:12:17.200 --> 00:12:19.879 We usually consider them constant over human history. 247 00:12:19.600 --> 00:12:23.720 Pretty much, except here. This study gave us the first 248 00:12:23.960 --> 00:12:28.919 continuous century plus. Look at this specific whitewarf formation phase 249 00:12:29.679 --> 00:12:30.799 and the numbers are startling. 250 00:12:30.919 --> 00:12:31.919 Oh okay, what did they find? 251 00:12:32.039 --> 00:12:34.919 They determined that the central star, that white dwarf, has 252 00:12:34.960 --> 00:12:38.440 increased its surface temperature by wapping three thousand degrees celsius 253 00:12:38.759 --> 00:12:41.759 since Williamina Fleming first recorded it back in eighteen ninety one. 254 00:12:41.879 --> 00:12:44.919 Three thousand degrees celsius in one hundred and thirty years. 255 00:12:45.039 --> 00:12:47.600 Yes, that breaks down to a heating rate of roughly 256 00:12:47.600 --> 00:12:49.759 one thousand degrees celsius every forty years. 257 00:12:49.960 --> 00:12:53.480 Wow, So in a single human generation that star gets 258 00:12:53.519 --> 00:12:57.320 substantially hotter. You could theoretically measure the change within a 259 00:12:57.320 --> 00:12:58.639 working astronomer's career. 260 00:12:58.799 --> 00:13:02.360 You absolutely could literally watching this dying star heat up 261 00:13:02.559 --> 00:13:04.080 dramatically almost in real. 262 00:13:03.919 --> 00:13:07.440 Time's that puts astronomical change on a human scale like 263 00:13:07.480 --> 00:13:10.840 almost nothing else. The source material compared it to our 264 00:13:10.879 --> 00:13:12.320 Sun's formation, Right it did. 265 00:13:12.559 --> 00:13:15.279 Our Sun during its own formation phase when it was 266 00:13:15.279 --> 00:13:19.080 settling down, saw a similar temperature increase, maybe a few 267 00:13:19.120 --> 00:13:22.639 thousand degrees, but that took something like ten million years. 268 00:13:22.759 --> 00:13:25.919 Ten million years. IC four eighteen did it in one 269 00:13:26.000 --> 00:13:26.720 hundred and thirty. 270 00:13:27.080 --> 00:13:31.000 It's deep time accelerated. This rapid heating happens as the 271 00:13:31.039 --> 00:13:34.279 star sheds its final eiter layers, like throwing off a 272 00:13:34.320 --> 00:13:38.720 blanket exposing the incredibly hot contracting core underneath. As that 273 00:13:38.759 --> 00:13:41.519 core shrinks under gravity, its surface area gets smaller, but 274 00:13:41.559 --> 00:13:45.279 the energy gets concentrated, so the surface temperature just skyrockets. 275 00:13:45.360 --> 00:13:48.399 Okay, that makes sense, rapid heating as the core is revealed. 276 00:13:48.440 --> 00:13:51.440 But here comes the paradox. Right, this is what messes 277 00:13:51.440 --> 00:13:52.080 with the models. 278 00:13:52.120 --> 00:13:55.159 This is the kicker. While that heating is incredibly fast 279 00:13:55.200 --> 00:13:58.159 in human terms, the study found that this rate, this 280 00:13:58.279 --> 00:14:01.679 one thousand degrees every forty years, is actually slower than 281 00:14:01.840 --> 00:14:04.120 current theoretical models predict for a star like this. 282 00:14:04.279 --> 00:14:06.919 Wait, it's heating up super fast, But our best physics 283 00:14:06.960 --> 00:14:08.559 says it should be heating up even faster. 284 00:14:08.919 --> 00:14:12.480 That's the puzzle. If you take the known properties of 285 00:14:12.679 --> 00:14:16.039 IC four eighteen it's mass, the negula's expansion rate, and 286 00:14:16.120 --> 00:14:20.240 plug them into our standard computer models of stellar evolution, 287 00:14:20.879 --> 00:14:23.720 those models predicts an even more rapid temperature increase than 288 00:14:23.759 --> 00:14:25.879 what we've observed over these one hundred and thirty years. 289 00:14:26.080 --> 00:14:28.600 So the star is putting on the brake somehow compared 290 00:14:28.639 --> 00:14:29.519 to the theory. 291 00:14:29.639 --> 00:14:32.600 Or perhaps the theory has the accelerator pushed down too hard. 292 00:14:33.039 --> 00:14:35.360 It suggests there's something we don't fully understand. Maybe some 293 00:14:35.559 --> 00:14:39.679 process is slowing the final collapse or moderating the thermal output. 294 00:14:39.759 --> 00:14:43.399 Could it be some residual, low level nuclear burning deeper 295 00:14:43.399 --> 00:14:47.200 inside than we expect, Or maybe the way the very 296 00:14:47.240 --> 00:14:50.360 last bits of mass are rejected affects the surface temperature 297 00:14:50.360 --> 00:14:51.279 profile differently. 298 00:14:51.360 --> 00:14:54.080 So the slight discrepancy in speed it points to a 299 00:14:54.120 --> 00:14:56.279 gap in our understanding of the physics right at the 300 00:14:56.360 --> 00:14:57.639 very end of a star's. 301 00:14:57.320 --> 00:15:00.639 Life, a potentially significant gap. If we don't white grasp 302 00:15:00.720 --> 00:15:02.200 the thermodynamics the heat. 303 00:15:02.039 --> 00:15:04.919 Flow, then we probably don't fully grasp the chemistry either. 304 00:15:06.080 --> 00:15:09.200 Right, So let's pivot to that. So what question? Why 305 00:15:09.240 --> 00:15:11.879 does a three thousand degree temperature difference or a slight 306 00:15:11.960 --> 00:15:15.279 mismatch in heating speed in a nebula two thousand light 307 00:15:15.360 --> 00:15:17.000 years away actually matter. 308 00:15:16.799 --> 00:15:19.440 To us because it connects directly to where the building 309 00:15:19.440 --> 00:15:22.759 blocks of life come from, carbon carbon exactly. This finding 310 00:15:22.799 --> 00:15:26.799 is crucial because these dying intermediate mass stars are the 311 00:15:26.799 --> 00:15:30.679 primary factories for creating and distributing elements heavier than helium 312 00:15:30.720 --> 00:15:34.480 back into space, and the analysis confirms IC four eighteen 313 00:15:34.679 --> 00:15:38.039 is explicitly a carbon rich nebula, meaning. 314 00:15:37.840 --> 00:15:40.080 The star itself cooked up a lot of carbon. 315 00:15:39.759 --> 00:15:43.200 Inside, synthesize vast amounts of it through nuclear fusion, and 316 00:15:43.240 --> 00:15:46.720 then through processes we call dredge up, mix that carbon 317 00:15:46.879 --> 00:15:49.200 up to its surface layers before puffing them off to 318 00:15:49.240 --> 00:15:50.279 form the nebula. 319 00:15:50.039 --> 00:15:53.399 And that ejected material, that beautiful spirograph shell we see 320 00:15:53.440 --> 00:15:54.399 full of carbon. 321 00:15:54.159 --> 00:15:57.559 Will eventually disperse and mix with the interstellar gas and dust. 322 00:15:57.960 --> 00:16:01.120 It becomes the raw material for the next generation of stars, planets, 323 00:16:01.360 --> 00:16:02.559 and potentially life. 324 00:16:02.720 --> 00:16:06.320 Absolutely a huge fraction of the carbon in the universe, 325 00:16:07.080 --> 00:16:09.919 the carbon that forms the basis of all organic chemistry, 326 00:16:09.960 --> 00:16:13.000 the carbon in you and me, originated in stars that 327 00:16:13.120 --> 00:16:14.440 went through exactly this phase. 328 00:16:14.519 --> 00:16:17.480 So tracing the carbon atoms in my handback many came 329 00:16:17.480 --> 00:16:20.080 from a star like IC four eighteen's progenitor. 330 00:16:20.279 --> 00:16:23.399 That's the cosmic cycle. So when IC four eighteen challenges 331 00:16:23.440 --> 00:16:26.240 our models of how these stars evolve and die, it 332 00:16:26.320 --> 00:16:29.879 directly challenges our understanding of how the ingredients essential for 333 00:16:29.919 --> 00:16:32.679 our existence were made and spread through the galaxy. 334 00:16:32.759 --> 00:16:35.360 And the problem isn't just the heating speed. Right There 335 00:16:35.399 --> 00:16:38.240 was another major conflict with the models related to the 336 00:16:38.279 --> 00:16:39.080 stars mass. 337 00:16:39.200 --> 00:16:41.639 Yes, this might be the most profound part. The study 338 00:16:41.759 --> 00:16:44.799 used observations of the Nebula and the white Dwarf to 339 00:16:44.960 --> 00:16:47.919 calculate the original mass of the star before it started 340 00:16:47.960 --> 00:16:48.480 shedding its. 341 00:16:48.440 --> 00:16:50.600 Layers, the progenitor mass. What did they find? 342 00:16:50.639 --> 00:16:52.840 They determined it was about one point four times the 343 00:16:52.840 --> 00:16:56.559 mass of our Sun, so a bit heftier than the Sun, 344 00:16:56.639 --> 00:16:57.639 but not dramatically So. 345 00:16:57.639 --> 00:17:01.519 Okay, one point four solar masses an empirical measurement based 346 00:17:01.559 --> 00:17:02.600 on the current system. 347 00:17:02.759 --> 00:17:07.279 Right. Now, here's the clash. Our standard stellar evolution models 348 00:17:07.759 --> 00:17:10.839 generally predict that a star needs to be significantly more 349 00:17:10.920 --> 00:17:13.640 massive to produce the amount of carbon enrichment we see 350 00:17:13.640 --> 00:17:14.599 in IC four eighteen. 351 00:17:14.720 --> 00:17:16.359 How much more massive, often in the. 352 00:17:16.400 --> 00:17:18.640 Range of say two point five to three times the 353 00:17:18.680 --> 00:17:21.440 mass of the Sun. The models suggested you needed that 354 00:17:21.519 --> 00:17:25.119 much more initial gravitational squeeze, that much more fuel to 355 00:17:25.200 --> 00:17:28.640 drive the nuclear reactions and the dredge up processes efficiently 356 00:17:28.720 --> 00:17:30.559 enough to create such a carbon rich outflow. 357 00:17:30.680 --> 00:17:33.480 Hold on, So the actual star they measured was substantially 358 00:17:33.519 --> 00:17:37.000 smaller than the model said was necessary, yet it somehow 359 00:17:37.039 --> 00:17:38.759 produced all that carbon exactly. 360 00:17:39.039 --> 00:17:41.960 It seems this one point four solar mass star was 361 00:17:42.119 --> 00:17:45.559 far more efficient at manufacturing and dejecting carbon than our 362 00:17:45.599 --> 00:17:46.759 standard models allowed for. 363 00:17:46.920 --> 00:17:48.880 How could that happen? Does it change how we think 364 00:17:48.920 --> 00:17:50.680 about that dredge up process? 365 00:17:50.960 --> 00:17:53.759 It certainly suggests we need to revisit it. The third 366 00:17:53.839 --> 00:17:57.079 dredge up is this complex process where convection currents deep 367 00:17:57.079 --> 00:18:01.160 inside the star bring freshly synthesized elements like carbon up 368 00:18:01.200 --> 00:18:03.920 to the surface layers. If a star of only one 369 00:18:03.960 --> 00:18:07.559 point four solar masses can do this so effectively, then 370 00:18:07.640 --> 00:18:10.359 either the minimum mass required for efficient dredge up is 371 00:18:10.400 --> 00:18:13.480 lower than we thought, or the process itself is more 372 00:18:13.480 --> 00:18:17.359 efficient in stars of this size than the models currently simulate. 373 00:18:17.559 --> 00:18:20.680 Either way, it means our fundamental understanding needs adjusting. 374 00:18:20.799 --> 00:18:23.920 It's a major revision. If the threshold for being a 375 00:18:23.960 --> 00:18:27.680 significant carbon source is lower, we'll think about it. There 376 00:18:27.720 --> 00:18:30.200 are many more stars born with around one point four 377 00:18:30.279 --> 00:18:33.880 solar masses than with two point five or three solar masses. 378 00:18:33.680 --> 00:18:36.400 So it could dramatically increase the number of stars contributing 379 00:18:36.440 --> 00:18:38.359 to the galaxy's carbon budget previsely. 380 00:18:38.559 --> 00:18:40.880 It potentially means the universe has been seated with the 381 00:18:40.880 --> 00:18:43.960 building blocks of life much more widely by a larger 382 00:18:44.000 --> 00:18:46.319 population of stars than we previously calculated. 383 00:18:46.400 --> 00:18:50.720 Wow, that's a huge implication stemming from observing one nebula carefully. 384 00:18:51.039 --> 00:18:54.559 It's a classic case of a single well studied object 385 00:18:54.759 --> 00:18:58.319 potentially breaking a widely accepted model, and it really highlights 386 00:18:58.359 --> 00:19:01.359 the power of that long term observational. 387 00:19:00.799 --> 00:19:02.319 Approach tying it all together. 388 00:19:02.559 --> 00:19:06.279 Absolutely, this mass discrepancy, this carbon puzzle, it only really 389 00:19:06.319 --> 00:19:09.240 comes into sharp focus when you combine the modern measurements 390 00:19:09.480 --> 00:19:12.240 with that full one hundred and thirty year history. Without 391 00:19:12.279 --> 00:19:16.400 tracking its evolution, seeing that rapid but not that rapid heating, 392 00:19:16.559 --> 00:19:20.000 confirming its stage of life, we wouldn't have the context 393 00:19:20.160 --> 00:19:22.319 to confidently challenge the mass models. 394 00:19:22.039 --> 00:19:24.319 Which brings us back full circle to the value of 395 00:19:24.359 --> 00:19:27.279 those old archives, those dusty glass plates. 396 00:19:27.319 --> 00:19:31.480 They're not just history, they're irreplaceable scientific data. They capture 397 00:19:31.559 --> 00:19:35.160 dynamics over time scales that no single modern mission, no 398 00:19:35.200 --> 00:19:38.480 matter how advanced, can replicate. You simply can't tell Hubble 399 00:19:38.559 --> 00:19:40.039 to wait one hundred and thirty years. 400 00:19:40.160 --> 00:19:43.440 We're relying on the meticulous work of astronomers from generations 401 00:19:43.440 --> 00:19:46.119