1 00:00:00,000 --> 00:00:01,440 Welcome back to Cosmos in a Pod. 2 00:00:01,440 --> 00:00:05,480 This is our Space and Astronomy series, episode 11. 3 00:00:05,480 --> 00:00:07,240 And today we're gonna be doing a deep dive 4 00:00:07,240 --> 00:00:09,960 into the fascinating process of star birth. 5 00:00:09,960 --> 00:00:10,780 Yeah. 6 00:00:10,780 --> 00:00:13,000 How stars, these engines of the universe 7 00:00:13,000 --> 00:00:14,040 come into existence. 8 00:00:14,040 --> 00:00:15,280 I'm really excited about this one. 9 00:00:15,280 --> 00:00:16,120 Me too. 10 00:00:16,120 --> 00:00:17,140 And you know what's really cool 11 00:00:17,140 --> 00:00:18,960 about understanding star birth? 12 00:00:18,960 --> 00:00:21,240 It's not just about stars themselves. 13 00:00:21,240 --> 00:00:24,040 It unlocks secrets about the elements 14 00:00:24,040 --> 00:00:25,880 that form everything around us. 15 00:00:25,880 --> 00:00:26,720 Right, exactly. 16 00:00:26,720 --> 00:00:28,800 You know, even planets and life itself. 17 00:00:28,800 --> 00:00:30,080 Yeah, that's what's so fascinating. 18 00:00:30,080 --> 00:00:32,160 We're not just talking about twinkling lights 19 00:00:32,160 --> 00:00:33,140 in the sky, right? 20 00:00:33,140 --> 00:00:33,980 Yeah. 21 00:00:33,980 --> 00:00:37,400 Stars are the fundamental building blocks of the universe. 22 00:00:37,400 --> 00:00:38,240 Yeah. 23 00:00:38,240 --> 00:00:39,360 They create the elements 24 00:00:39,360 --> 00:00:41,440 that make up everything around us. 25 00:00:41,440 --> 00:00:42,560 Literally everything. 26 00:00:42,560 --> 00:00:44,760 You mean this podcasting equipment. 27 00:00:44,760 --> 00:00:45,600 Wow. 28 00:00:45,600 --> 00:00:47,120 It all started with a star. 29 00:00:47,120 --> 00:00:49,400 I mean, that is a pretty incredible thought, isn't it? 30 00:00:49,400 --> 00:00:50,220 It is. 31 00:00:50,220 --> 00:00:51,520 To think that we're all made of stardust. 32 00:00:51,520 --> 00:00:52,360 Yeah. 33 00:00:52,360 --> 00:00:54,320 But where did these stellar giants even come from? 34 00:00:54,320 --> 00:00:56,200 Yeah, they don't just magically appear, do they? 35 00:00:56,200 --> 00:01:00,440 It all begins in these vast clouds of gas and dust 36 00:01:00,440 --> 00:01:01,560 called nebulae. 37 00:01:01,560 --> 00:01:02,400 Yeah. 38 00:01:02,400 --> 00:01:04,320 Think of them as cosmic nurseries 39 00:01:04,320 --> 00:01:07,400 filled with the raw materials for star formation. 40 00:01:07,400 --> 00:01:09,320 So nebulae are like the cosmic kitchens 41 00:01:09,320 --> 00:01:10,480 where stars are cooked up. 42 00:01:10,480 --> 00:01:11,640 I like that analogy. 43 00:01:11,640 --> 00:01:12,680 What are they even made of? 44 00:01:12,680 --> 00:01:14,660 So primarily hydrogen, 45 00:01:14,660 --> 00:01:17,320 which is the most abundant element in the universe. 46 00:01:17,320 --> 00:01:18,160 Right. 47 00:01:18,160 --> 00:01:19,520 With a little sprinkle of helium 48 00:01:19,520 --> 00:01:21,440 and some traces of heavier elements. 49 00:01:21,440 --> 00:01:22,280 Okay. 50 00:01:22,280 --> 00:01:24,960 Now these nebulae can span light years across. 51 00:01:24,960 --> 00:01:26,320 And they're not just massive, 52 00:01:26,320 --> 00:01:28,480 they're also visually stunning. 53 00:01:28,480 --> 00:01:29,400 Through telescopes, 54 00:01:29,400 --> 00:01:31,460 they look like celestial tapestries 55 00:01:31,460 --> 00:01:33,480 glowing with vibrant colors. 56 00:01:33,480 --> 00:01:37,720 I'm picturing like these massive clouds of gas and dust 57 00:01:37,720 --> 00:01:39,960 just floating around in space. 58 00:01:39,960 --> 00:01:42,840 It's hard to even grasp the scale of it all. 59 00:01:42,840 --> 00:01:43,840 It's mind-boggling. 60 00:01:43,840 --> 00:01:44,800 It really is. 61 00:01:44,800 --> 00:01:48,440 But how do these clouds go from being just diffuse gas 62 00:01:48,440 --> 00:01:49,800 to becoming stars? 63 00:01:49,800 --> 00:01:51,240 Well, that's where gravity steps. 64 00:01:51,240 --> 00:01:53,800 Gravity is like the master sculptor of the universe. 65 00:01:53,800 --> 00:01:54,640 Right. 66 00:01:54,640 --> 00:01:55,480 It's all together. 67 00:01:55,480 --> 00:01:56,320 And in the case of nebulae, 68 00:01:56,320 --> 00:01:58,520 it can trigger the collapse of these clouds 69 00:01:58,520 --> 00:01:59,960 leading to the birth of stars. 70 00:01:59,960 --> 00:02:02,080 So gravity is like the cosmic matchmaker. 71 00:02:02,080 --> 00:02:02,920 Yeah. 72 00:02:02,920 --> 00:02:04,000 Bringing all this gas and dust together. 73 00:02:04,000 --> 00:02:04,840 It's need all to get. 74 00:02:04,840 --> 00:02:06,840 But what sets off this chain reaction? 75 00:02:06,840 --> 00:02:07,680 Right. 76 00:02:07,680 --> 00:02:08,520 What causes these clouds 77 00:02:08,520 --> 00:02:10,560 to start collapsing in the first place? 78 00:02:10,560 --> 00:02:12,720 Well, think of it like a cosmic domino effect. 79 00:02:12,720 --> 00:02:13,560 Oh, cool. 80 00:02:13,560 --> 00:02:15,560 Something needs to nudge those dominoes right. 81 00:02:15,560 --> 00:02:16,400 Yeah. 82 00:02:16,400 --> 00:02:18,680 It could be a shockwave from a nearby supernova, 83 00:02:18,680 --> 00:02:20,800 the death of a massive star, 84 00:02:20,800 --> 00:02:23,540 or it could be the collision of two galaxies 85 00:02:23,540 --> 00:02:26,800 sending ripples through space that disturbed these clouds. 86 00:02:26,800 --> 00:02:28,880 So it was like a cosmic chain reaction. 87 00:02:28,880 --> 00:02:29,720 Exactly. 88 00:02:29,720 --> 00:02:31,600 With one event triggering the next 89 00:02:31,600 --> 00:02:33,280 leading to the birth of new stars. 90 00:02:33,280 --> 00:02:34,400 That's the beauty of it. 91 00:02:34,400 --> 00:02:35,240 That's amazing. 92 00:02:35,240 --> 00:02:37,240 But let's focus on that collapse for a moment. 93 00:02:37,240 --> 00:02:40,560 What happens inside these clouds when gravity takes over? 94 00:02:40,560 --> 00:02:44,200 So as gravity pulls the gas and dust inward, 95 00:02:44,200 --> 00:02:46,920 it forms these dense clumps called cores. 96 00:02:46,920 --> 00:02:47,760 Cores. 97 00:02:47,760 --> 00:02:48,600 Yeah. 98 00:02:48,600 --> 00:02:50,340 Imagine a snowball gathering more and more snow 99 00:02:50,340 --> 00:02:51,560 as it rolls downhill. 100 00:02:51,560 --> 00:02:52,400 Okay. 101 00:02:52,400 --> 00:02:54,560 And these cores are like stellar embryos, 102 00:02:54,560 --> 00:02:56,200 the seeds of future stars. 103 00:02:56,200 --> 00:02:58,920 Okay, so we have these dense clumps of gas and dust, 104 00:02:58,920 --> 00:02:59,740 these cores. 105 00:02:59,740 --> 00:03:00,580 Right. 106 00:03:00,580 --> 00:03:02,400 What happens to them as they continue to collapse 107 00:03:02,400 --> 00:03:03,560 under their own gravity? 108 00:03:03,560 --> 00:03:06,700 As they contract, they heat up and start to spin. 109 00:03:06,700 --> 00:03:08,520 It's like a figure skater pulling their arms 110 00:03:08,520 --> 00:03:10,240 and spinning faster and faster. 111 00:03:10,240 --> 00:03:11,080 Oh. 112 00:03:11,080 --> 00:03:15,080 And this spinning motion flattens the collapsing material 113 00:03:15,080 --> 00:03:18,220 into a disk with most of the mass concentrated 114 00:03:18,220 --> 00:03:19,060 at the center. 115 00:03:19,060 --> 00:03:20,680 So it's like a cosmic ballet. 116 00:03:20,680 --> 00:03:21,520 It is. 117 00:03:21,520 --> 00:03:24,920 Gravity and rotation shaping these stellar embryos. 118 00:03:24,920 --> 00:03:25,760 Yeah. 119 00:03:25,760 --> 00:03:27,480 And what's at the center of this disk? 120 00:03:27,480 --> 00:03:28,520 Is that the star? 121 00:03:28,520 --> 00:03:29,680 Almost. 122 00:03:29,680 --> 00:03:32,400 That central mass is what we call a protostar. 123 00:03:32,400 --> 00:03:35,320 It's a young forming star that hasn't quite ignited yet. 124 00:03:35,320 --> 00:03:36,160 Hold on. 125 00:03:36,160 --> 00:03:37,840 You're saying a protostar isn't a real star? 126 00:03:37,840 --> 00:03:39,080 What's missing? 127 00:03:39,080 --> 00:03:40,440 What makes a star a star? 128 00:03:40,440 --> 00:03:42,920 The key ingredient is nuclear fusion. 129 00:03:42,920 --> 00:03:45,600 That's the process where hydrogen atoms fuse together 130 00:03:45,600 --> 00:03:49,140 to form helium, releasing a tremendous amount of energy. 131 00:03:49,140 --> 00:03:51,160 That energy is what makes stars shine. 132 00:03:51,160 --> 00:03:51,660 OK. 133 00:03:51,660 --> 00:03:53,600 So a protostar is like a star in a waving. 134 00:03:53,600 --> 00:03:54,240 Exactly. 135 00:03:54,240 --> 00:03:56,000 Still gathering material and getting ready 136 00:03:56,000 --> 00:03:57,280 for that big fusion moment. 137 00:03:57,280 --> 00:03:58,800 It's building up to the main event. 138 00:03:58,800 --> 00:04:01,900 But if they haven't ignited yet, how do we even know they exist? 139 00:04:01,900 --> 00:04:03,980 That's a great question. 140 00:04:03,980 --> 00:04:07,560 Even though they're shrouded in cocoons of gas and dust, 141 00:04:07,560 --> 00:04:09,840 protostars aren't completely invisible. 142 00:04:09,840 --> 00:04:12,320 They emit infrared radiation, which 143 00:04:12,320 --> 00:04:14,120 we can detect with telescopes. 144 00:04:14,120 --> 00:04:14,700 Gotcha. 145 00:04:14,700 --> 00:04:17,600 It's like seeing a faint heat signature, a telltale sign 146 00:04:17,600 --> 00:04:19,040 that a star is being born. 147 00:04:19,040 --> 00:04:21,480 So we're literally peering into stellar nurseries. 148 00:04:21,480 --> 00:04:22,520 CR. 149 00:04:22,520 --> 00:04:24,320 And witnessing the birth of stars. 150 00:04:24,320 --> 00:04:25,400 It's incredible, isn't it? 151 00:04:25,400 --> 00:04:26,760 That is really cool. 152 00:04:26,760 --> 00:04:28,760 But you mentioned that these protostars are still 153 00:04:28,760 --> 00:04:29,720 gathering material. 154 00:04:29,720 --> 00:04:30,120 Yeah. 155 00:04:30,120 --> 00:04:31,560 Where's this material coming from? 156 00:04:31,560 --> 00:04:32,440 It's all around them. 157 00:04:32,440 --> 00:04:34,320 Remember that spinning disk we talked about? 158 00:04:34,320 --> 00:04:34,820 Yeah. 159 00:04:34,820 --> 00:04:36,960 It's filled with gas and dust that 160 00:04:36,960 --> 00:04:39,920 continues to fall onto the protostar, like rain 161 00:04:39,920 --> 00:04:41,640 feeding a growing river. 162 00:04:41,640 --> 00:04:44,000 So it's a constant process of accretion, 163 00:04:44,000 --> 00:04:47,200 with the protostar gobbling up more and more material 164 00:04:47,200 --> 00:04:48,800 from its surroundings. 165 00:04:48,800 --> 00:04:50,680 But is this a peaceful process, or are there 166 00:04:50,680 --> 00:04:52,400 some dramatic events happening as well? 167 00:04:52,400 --> 00:04:55,320 Well, it's not exactly a quiet tea party. 168 00:04:55,320 --> 00:04:56,920 As the protostar grows, it throws 169 00:04:56,920 --> 00:04:59,440 some pretty impressive tantrums. 170 00:04:59,440 --> 00:05:03,000 Powerful jets of gas called bipolar outflows 171 00:05:03,000 --> 00:05:04,320 shoot out from its poles. 172 00:05:04,320 --> 00:05:05,560 Bipolar outflows. 173 00:05:05,560 --> 00:05:06,720 That sounds intense. 174 00:05:06,720 --> 00:05:08,920 What causes these jets, and what do they do? 175 00:05:08,920 --> 00:05:12,080 Think of it like the protostar clearing its throat, 176 00:05:12,080 --> 00:05:15,040 getting rid of excess material as it feeds. 177 00:05:15,040 --> 00:05:17,320 These jets can extend for light years, 178 00:05:17,320 --> 00:05:19,880 blasting away gas and dust carving cavities 179 00:05:19,880 --> 00:05:21,240 in the surrounding nebula. 180 00:05:21,240 --> 00:05:23,960 It's like the protostar is saying, make way, folks. 181 00:05:23,960 --> 00:05:25,240 A star is being born here. 182 00:05:25,240 --> 00:05:26,440 Exactly. 183 00:05:26,440 --> 00:05:27,880 It needs its space. 184 00:05:27,880 --> 00:05:30,440 But how do these bipolar outflows actually form? 185 00:05:30,440 --> 00:05:33,100 It sounds like there are some pretty intense forces at work. 186 00:05:33,100 --> 00:05:33,760 Absolutely. 187 00:05:33,760 --> 00:05:36,400 It has to do with the interplay between gravity rotation 188 00:05:36,400 --> 00:05:37,600 and magnetic fields. 189 00:05:37,600 --> 00:05:38,360 Oh, wow. 190 00:05:38,360 --> 00:05:40,840 It's a bit complex, but essentially the spinning 191 00:05:40,840 --> 00:05:43,800 motion and magnetic fields of the protostar channel material 192 00:05:43,800 --> 00:05:46,400 outwards, creating these powerful jets. 193 00:05:46,400 --> 00:05:49,320 So we have this protostar growing larger by the minute, 194 00:05:49,320 --> 00:05:52,760 blasting away material with these intense jets. 195 00:05:52,760 --> 00:05:53,960 What happens next? 196 00:05:53,960 --> 00:05:59,440 When does a protostar finally become a real star? 197 00:05:59,440 --> 00:06:01,520 That happens when the core of the protostar 198 00:06:01,520 --> 00:06:04,520 reaches a critical temperature of about 10 million degrees 199 00:06:04,520 --> 00:06:05,760 Celsius. 200 00:06:05,760 --> 00:06:08,520 That's when the nuclear fusion engine ignites. 201 00:06:08,520 --> 00:06:10,980 It's like flipping a switch and suddenly boom, a star is born. 202 00:06:10,980 --> 00:06:12,640 What happens at that moment of ignition? 203 00:06:12,640 --> 00:06:14,120 It's not just a moment. 204 00:06:14,120 --> 00:06:15,640 It's a process. 205 00:06:15,640 --> 00:06:18,160 As the core temperature and pressure increase, 206 00:06:18,160 --> 00:06:21,040 hydrogen atoms are forced closer and closer together 207 00:06:21,040 --> 00:06:23,800 until they finally overcome their natural repulsion 208 00:06:23,800 --> 00:06:25,720 and fuse to form helium. 209 00:06:25,720 --> 00:06:27,360 So it's like a cosmic pressure cooker. 210 00:06:27,360 --> 00:06:28,080 It is. 211 00:06:28,080 --> 00:06:30,240 Squeezing those hydrogen atoms until they fuse. 212 00:06:30,240 --> 00:06:31,160 Exactly. 213 00:06:31,160 --> 00:06:33,520 And what happens to the energy released by this fusion 214 00:06:33,520 --> 00:06:34,160 process? 215 00:06:34,160 --> 00:06:36,360 That energy is what makes the star shine. 216 00:06:36,360 --> 00:06:38,600 It creates outward pressure that counteracts 217 00:06:38,600 --> 00:06:40,240 the inward pull of gravity. 218 00:06:40,240 --> 00:06:42,480 It's like a cosmic balancing act. 219 00:06:42,480 --> 00:06:44,920 Gravity pulling in fusion, pushing out, 220 00:06:44,920 --> 00:06:47,800 and the star finding its perfect equilibrium. 221 00:06:47,800 --> 00:06:51,160 So a star is born from this delicate balance between gravity 222 00:06:51,160 --> 00:06:52,360 and nuclear fusion. 223 00:06:52,360 --> 00:06:53,520 That's the essence of it. 224 00:06:53,520 --> 00:06:54,760 That's amazing. 225 00:06:54,760 --> 00:06:57,120 But what determines what kind of star will form? 226 00:06:57,120 --> 00:06:58,760 Are all stars created equal? 227 00:06:58,760 --> 00:06:59,920 Not at all. 228 00:06:59,920 --> 00:07:02,160 The mass of the protostar plays a crucial role 229 00:07:02,160 --> 00:07:04,080 in determining the fate of the star. 230 00:07:04,080 --> 00:07:07,280 More massive protostars will form larger, hotter, and more 231 00:07:07,280 --> 00:07:08,800 luminous stars. 232 00:07:08,800 --> 00:07:11,480 While smaller protostars will give rise to cooler, dimmer, 233 00:07:11,480 --> 00:07:12,840 and longer lived stars. 234 00:07:12,840 --> 00:07:14,440 So it's like a cosmic recipe. 235 00:07:14,440 --> 00:07:14,920 It is. 236 00:07:14,920 --> 00:07:16,480 With mass being the key ingredient 237 00:07:16,480 --> 00:07:17,720 that determines the outcome. 238 00:07:17,720 --> 00:07:19,160 The mass is everything. 239 00:07:19,160 --> 00:07:21,480 But what if a protostar doesn't have enough mass 240 00:07:21,480 --> 00:07:23,560 to ignite nuclear fusion? 241 00:07:23,560 --> 00:07:24,760 What happens then? 242 00:07:24,760 --> 00:07:28,120 That's where things get a bit more unconventional. 243 00:07:28,120 --> 00:07:30,640 If a protostar doesn't reach a critical mass, 244 00:07:30,640 --> 00:07:33,040 it never quite makes it to stardom. 245 00:07:33,040 --> 00:07:35,200 It becomes what we call a brown dwarf. 246 00:07:35,200 --> 00:07:35,960 Brown dwarf. 247 00:07:35,960 --> 00:07:38,000 So it's like the almost stars. 248 00:07:38,000 --> 00:07:39,640 Like they tried out for the cosmic choir, 249 00:07:39,640 --> 00:07:41,240 but didn't quite hit the high notes. 250 00:07:41,240 --> 00:07:42,720 That's a great analogy. 251 00:07:42,720 --> 00:07:45,120 Brown dwarfs are these fascinating objects 252 00:07:45,120 --> 00:07:48,240 that straddle the line between stars and planets. 253 00:07:48,240 --> 00:07:51,160 They're bigger than planets, but not quite massive enough 254 00:07:51,160 --> 00:07:54,000 to sustain nuclear fusion like a star. 255 00:07:54,000 --> 00:07:56,320 So they're kind of like the cosmic underachievers. 256 00:07:56,320 --> 00:07:57,520 You could say that. 257 00:07:57,520 --> 00:08:00,640 But even if they don't shine as brightly as stars, 258 00:08:00,640 --> 00:08:02,560 they must still be pretty interesting to study. 259 00:08:02,560 --> 00:08:03,560 Absolutely. 260 00:08:03,560 --> 00:08:05,440 Brown dwarfs offer unique insights 261 00:08:05,440 --> 00:08:07,600 into the lower limits of star formation 262 00:08:07,600 --> 00:08:10,640 and the diversity of objects that populate the universe. 263 00:08:10,640 --> 00:08:13,520 So we've seen how gravity kickstarts this whole process. 264 00:08:13,520 --> 00:08:16,760 But what happens next inside these collapsing clouds? 265 00:08:16,760 --> 00:08:18,480 That's where things get really interesting. 266 00:08:18,480 --> 00:08:19,480 It sure does. 267 00:08:19,480 --> 00:08:22,080 Yeah, it's like a cosmic ecosystem, isn't it? 268 00:08:22,080 --> 00:08:24,640 The birth of a star doesn't just happen in isolation. 269 00:08:24,640 --> 00:08:27,160 It transforms the entire surrounding nebula. 270 00:08:27,160 --> 00:08:28,000 Yeah, you're right. 271 00:08:28,000 --> 00:08:29,760 It's like a ripple effect spreading outwards 272 00:08:29,760 --> 00:08:31,080 from that newborn star. 273 00:08:31,080 --> 00:08:32,080 Exactly. 274 00:08:32,080 --> 00:08:33,800 So how does the birth of a star impact 275 00:08:33,800 --> 00:08:35,840 the nebula it's born from? 276 00:08:35,840 --> 00:08:39,160 So the intense radiation and powerful stellar winds 277 00:08:39,160 --> 00:08:42,320 from these newborn stars, they kind of blow away 278 00:08:42,320 --> 00:08:45,920 the remaining gas and dust, carving out vast cavities, 279 00:08:45,920 --> 00:08:49,200 and sculpting the nebula into these intricate shapes. 280 00:08:49,200 --> 00:08:51,200 So it's like the star is flexing its muscles, 281 00:08:51,200 --> 00:08:53,440 pushing away the remnants of its birth cloud? 282 00:08:53,440 --> 00:08:55,160 Yeah, you could say that. 283 00:08:55,160 --> 00:08:57,720 Are there any famous examples of these sculpted nebulae 284 00:08:57,720 --> 00:08:58,680 that we can actually see? 285 00:08:58,680 --> 00:08:59,720 Oh, absolutely. 286 00:08:59,720 --> 00:09:02,800 One of the most iconic examples are the pillars of creation 287 00:09:02,800 --> 00:09:03,800 in the Eagle Nebula. 288 00:09:03,800 --> 00:09:04,680 Oh, yeah. 289 00:09:04,680 --> 00:09:07,880 These towering columns of gas and dust, 290 00:09:07,880 --> 00:09:09,440 literally where stars are being born, 291 00:09:09,440 --> 00:09:11,200 illuminated by the intense radiation 292 00:09:11,200 --> 00:09:12,440 of nearby young stars. 293 00:09:12,440 --> 00:09:13,760 Wow, the pillars of creation. 294 00:09:13,760 --> 00:09:14,680 I've seen pictures of those. 295 00:09:14,680 --> 00:09:16,200 They're absolutely breathtaking. 296 00:09:16,200 --> 00:09:17,680 They are incredible. 297 00:09:17,680 --> 00:09:19,480 It's amazing to think that those structures 298 00:09:19,480 --> 00:09:22,080 are being shaped by the very stars they're giving birth to. 299 00:09:22,080 --> 00:09:23,720 Yeah, it's a beautiful illustration 300 00:09:23,720 --> 00:09:27,480 of the dynamic interplay between stars and their environment. 301 00:09:27,480 --> 00:09:29,040 And this sculpting process can actually 302 00:09:29,040 --> 00:09:31,760 trigger a chain reaction leading to the birth of even more 303 00:09:31,760 --> 00:09:32,400 stars. 304 00:09:32,400 --> 00:09:33,040 Oh, wow. 305 00:09:33,040 --> 00:09:34,720 So it's a self-propagating cycle. 306 00:09:34,720 --> 00:09:35,240 It is. 307 00:09:35,240 --> 00:09:38,120 One star's birth can trigger the formation of many others. 308 00:09:38,120 --> 00:09:39,480 Exactly. 309 00:09:39,480 --> 00:09:42,200 The shock waves from stellar winds and supernovae 310 00:09:42,200 --> 00:09:44,280 can compress nearby gas and dust, 311 00:09:44,280 --> 00:09:47,160 creating new stellar nurseries and perpetuating 312 00:09:47,160 --> 00:09:48,720 the cycle of star birth. 313 00:09:48,720 --> 00:09:51,720 It's a cosmic dance of creation and destruction. 314 00:09:51,720 --> 00:09:52,640 That's incredible. 315 00:09:52,640 --> 00:09:54,840 It makes you realize that the universe is constantly 316 00:09:54,840 --> 00:09:58,120 evolving, with new stars being born all the time. 317 00:09:58,120 --> 00:10:00,240 But what about the stars themselves? 318 00:10:00,240 --> 00:10:03,440 Once a star ignites and reaches that stable state, 319 00:10:03,440 --> 00:10:04,640 what happens next? 320 00:10:04,640 --> 00:10:07,320 Well, that stable state, what we call the main sequence, 321 00:10:07,320 --> 00:10:10,600 can last for millions, billions, or even trillions of years, 322 00:10:10,600 --> 00:10:12,240 depending on the star's mass. 323 00:10:12,240 --> 00:10:14,480 Wait, trillions of years? 324 00:10:14,480 --> 00:10:16,120 That's an incredibly long time. 325 00:10:16,120 --> 00:10:16,800 It is. 326 00:10:16,800 --> 00:10:20,240 What's happening inside a star during this main sequence phase? 327 00:10:20,240 --> 00:10:22,120 It's all about balance. 328 00:10:22,120 --> 00:10:24,880 The outward pressure from nuclear fusion in the core 329 00:10:24,880 --> 00:10:27,840 perfectly counteracts the inward pull of gravity. 330 00:10:27,840 --> 00:10:29,720 It's this delicate equilibrium that 331 00:10:29,720 --> 00:10:32,840 allows the star to shine steadily for eons. 332 00:10:32,840 --> 00:10:36,000 So it's like a cosmic tug of war with gravity and fusion 333 00:10:36,000 --> 00:10:37,680 locked in this epic battle. 334 00:10:37,680 --> 00:10:39,360 Yeah, that's a great way to put it. 335 00:10:39,360 --> 00:10:41,320 And during this epic battle, the star 336 00:10:41,320 --> 00:10:44,000 is converting hydrogen to helium in its core, 337 00:10:44,000 --> 00:10:46,160 producing the energy that makes it shine. 338 00:10:46,160 --> 00:10:48,200 OK, but what happens when the star starts 339 00:10:48,200 --> 00:10:49,920 to run out of hydrogen fuel? 340 00:10:49,920 --> 00:10:51,400 Does the party just end? 341 00:10:51,400 --> 00:10:52,520 Not quite. 342 00:10:52,520 --> 00:10:54,560 The star has a few tricks up its sleeve. 343 00:10:54,560 --> 00:10:56,160 As the hydrogen in the core depletes, 344 00:10:56,160 --> 00:10:58,200 the core starts to contract. 345 00:10:58,200 --> 00:11:00,040 And this causes the temperature and pressure 346 00:11:00,040 --> 00:11:01,480 to rise even further. 347 00:11:01,480 --> 00:11:04,440 So the star is trying to squeeze every last bit of energy 348 00:11:04,440 --> 00:11:05,760 out of its remaining fuel. 349 00:11:05,760 --> 00:11:06,520 Exactly. 350 00:11:06,520 --> 00:11:08,360 It's trying to keep the party going. 351 00:11:08,360 --> 00:11:11,160 But what happens when even that fuel runs out? 352 00:11:11,160 --> 00:11:13,120 That's when things get really interesting. 353 00:11:13,120 --> 00:11:15,240 For stars like our sun, the next stage 354 00:11:15,240 --> 00:11:18,840 involves fusing helium into carbon and oxygen. 355 00:11:18,840 --> 00:11:20,760 This process releases even more energy, 356 00:11:20,760 --> 00:11:24,080 causing the star's outer layers to expand and cool, 357 00:11:24,080 --> 00:11:26,600 transforming it into a red giant. 358 00:11:26,600 --> 00:11:27,160 A red giant. 359 00:11:27,160 --> 00:11:27,480 Yes. 360 00:11:27,480 --> 00:11:29,120 Those are the enormous reddish stars 361 00:11:29,120 --> 00:11:30,320 we see in the night sky, right? 362 00:11:30,320 --> 00:11:31,320 Exactly. 363 00:11:31,320 --> 00:11:33,720 And while this expansion might seem impressive, 364 00:11:33,720 --> 00:11:35,320 it's actually a sign that the star is 365 00:11:35,320 --> 00:11:37,160 approaching its twilight years. 366 00:11:37,160 --> 00:11:39,560 So even giants have their limits. 367 00:11:39,560 --> 00:11:40,160 They do. 368 00:11:40,160 --> 00:11:42,320 But what happens after a star has burned 369 00:11:42,320 --> 00:11:44,200 through all its helium? 370 00:11:44,200 --> 00:11:47,880 What's the final curtain call for a red giant? 371 00:11:47,880 --> 00:11:49,880 Well, that depends on the star's mass. 372 00:11:49,880 --> 00:11:50,380 OK. 373 00:11:50,380 --> 00:11:53,560 For smaller stars like our sun, the outer layers 374 00:11:53,560 --> 00:11:55,400 will eventually drift off into space, 375 00:11:55,400 --> 00:11:57,600 forming a beautiful planetary nebula, 376 00:11:57,600 --> 00:12:01,120 leaving behind a dense hot core called a white dwarf. 377 00:12:01,120 --> 00:12:03,240 Wait, so the death of a star can be beautiful? 378 00:12:03,240 --> 00:12:04,480 It can be a stunning sight. 379 00:12:04,480 --> 00:12:06,960 I always imagined it would be more of an explosive event. 380 00:12:06,960 --> 00:12:08,240 Well, it can be both. 381 00:12:08,240 --> 00:12:10,600 While smaller stars fade away gracefully, 382 00:12:10,600 --> 00:12:13,280 massive stars go out with a supernova. 383 00:12:13,280 --> 00:12:14,040 Now we're talking. 384 00:12:14,040 --> 00:12:14,540 Yes. 385 00:12:14,540 --> 00:12:15,280 Supernova. 386 00:12:15,280 --> 00:12:15,840 Yes. 387 00:12:15,840 --> 00:12:17,800 Those are the cosmic fireworks shows I've heard about. 388 00:12:17,800 --> 00:12:18,680 Exactly. 389 00:12:18,680 --> 00:12:19,760 Tell me more about those. 390 00:12:19,760 --> 00:12:22,680 So when a massive star exhausts its nuclear fuel, 391 00:12:22,680 --> 00:12:24,720 its core collapses catastrophically. 392 00:12:24,720 --> 00:12:25,360 Oh, wow. 393 00:12:25,360 --> 00:12:27,200 This collapse triggers a shockwave 394 00:12:27,200 --> 00:12:29,760 that rips through the star, causing it to explode 395 00:12:29,760 --> 00:12:31,480 with unimaginable force. 396 00:12:31,480 --> 00:12:33,880 So it's like the star is imploding and then exploding 397 00:12:33,880 --> 00:12:35,000 outwards all at once. 398 00:12:35,000 --> 00:12:36,280 Pretty much. 399 00:12:36,280 --> 00:12:38,160 That sounds incredibly violent. 400 00:12:38,160 --> 00:12:41,120 It's one of the most powerful events in the universe. 401 00:12:41,120 --> 00:12:43,040 The energy released in a supernova 402 00:12:43,040 --> 00:12:46,000 can briefly outshine an entire galaxy. 403 00:12:46,000 --> 00:12:47,160 Wow. 404 00:12:47,160 --> 00:12:50,560 Just imagine witnessing a supernova from Earth. 405 00:12:50,560 --> 00:12:53,560 It would be like a new star suddenly appearing in the sky. 406 00:12:53,560 --> 00:12:55,700 It would be an incredible sight to behold. 407 00:12:55,700 --> 00:12:59,240 And these supernovae aren't just visually stunning. 408 00:12:59,240 --> 00:13:01,280 They're incredibly important for the evolution 409 00:13:01,280 --> 00:13:01,920 of the universe. 410 00:13:01,920 --> 00:13:03,280 OK, I'm all ears. 411 00:13:03,280 --> 00:13:06,680 How do supernovae play a role in the grand scheme of things? 412 00:13:06,680 --> 00:13:09,840 Well, supernovae are responsible for scattering heavy elements 413 00:13:09,840 --> 00:13:12,440 forged in the star's core throughout space. 414 00:13:12,440 --> 00:13:13,080 OK. 415 00:13:13,080 --> 00:13:15,560 These elements, like carbon oxygen and iron, 416 00:13:15,560 --> 00:13:17,560 they're the building blocks of planet's life 417 00:13:17,560 --> 00:13:19,280 and everything we see around us. 418 00:13:19,280 --> 00:13:21,680 Wait, so you're telling me that the atoms in our bodies 419 00:13:21,680 --> 00:13:25,480 were once part of stars that exploded billions of years ago? 420 00:13:25,480 --> 00:13:27,360 We are literally made of stardust. 421 00:13:27,360 --> 00:13:28,880 That's a beautiful way to put it. 422 00:13:28,880 --> 00:13:31,080 The calcium in your bones, the iron in your blood, 423 00:13:31,080 --> 00:13:33,680 all of it was created in the heart of a dying star 424 00:13:33,680 --> 00:13:36,320 and scattered across the cosmos by a supernova. 425 00:13:36,320 --> 00:13:37,720 That's mind blowing. 426 00:13:37,720 --> 00:13:40,880 So not only do supernovae create the elements for life, 427 00:13:40,880 --> 00:13:42,880 but they also trigger new star formation 428 00:13:42,880 --> 00:13:45,080 by compressing nearby gas and dust. 429 00:13:45,080 --> 00:13:46,480 It's a full circle moment. 430 00:13:46,480 --> 00:13:47,340 It really is. 431 00:13:47,340 --> 00:13:51,300 It's a cycle of death and rebirth on a cosmic scale. 432 00:13:51,300 --> 00:13:53,260 And from the remnants of these supernovae, 433 00:13:53,260 --> 00:13:56,360 even more exotic objects can emerge, 434 00:13:56,360 --> 00:13:59,280 neutron stars and black holes. 435 00:13:59,280 --> 00:14:01,240 OK, now we're going to do the really mysterious stuff. 436 00:14:01,240 --> 00:14:03,720 Neutron stars and black holes, they sound like something 437 00:14:03,720 --> 00:14:04,560 out of science fiction. 438 00:14:04,560 --> 00:14:06,360 They do have a certain mystique to them. 439 00:14:06,360 --> 00:14:07,680 What exactly are they? 440 00:14:07,680 --> 00:14:10,400 All right, so we're back with Cosmos in a pod 441 00:14:10,400 --> 00:14:13,920 and ready to unravel the mysteries of neutron stars 442 00:14:13,920 --> 00:14:15,040 and black holes. 443 00:14:15,040 --> 00:14:18,320 These objects are like the ultimate cosmic enigmas, 444 00:14:18,320 --> 00:14:20,520 pushing the boundaries of what we thought was possible. 445 00:14:20,520 --> 00:14:21,280 They really are. 446 00:14:21,280 --> 00:14:23,360 They're the remnants of massive stars 447 00:14:23,360 --> 00:14:25,360 that have reached the end of their lives, 448 00:14:25,360 --> 00:14:26,800 collapsed under their own gravity, 449 00:14:26,800 --> 00:14:29,080 and transformed into something extraordinary. 450 00:14:29,080 --> 00:14:31,240 OK, so let's start with neutron stars. 451 00:14:31,240 --> 00:14:33,120 You mentioned that they're incredibly dense. 452 00:14:33,120 --> 00:14:35,000 Can you give us a sense of just how extreme 453 00:14:35,000 --> 00:14:36,240 we're talking about here? 454 00:14:36,240 --> 00:14:38,720 Imagine taking the entire mass of the sun, 455 00:14:38,720 --> 00:14:41,960 all that fiery churning plasma, and squeezing it 456 00:14:41,960 --> 00:14:43,920 into an object the size of a city. 457 00:14:43,920 --> 00:14:46,120 That's the density of a neutron star. 458 00:14:46,120 --> 00:14:49,320 Wow, that's hard to even wrap my head around. 459 00:14:49,320 --> 00:14:51,040 What would even happen if we could somehow 460 00:14:51,040 --> 00:14:54,880 bring a teaspoonful of neutron star material back to Earth? 461 00:14:54,880 --> 00:14:58,040 Let's just say you wouldn't want to be standing anywhere 462 00:14:58,040 --> 00:14:58,540 near it. 463 00:14:58,540 --> 00:15:00,080 A teaspoon of neutron star material 464 00:15:00,080 --> 00:15:02,400 would weigh billions of tons on Earth. 465 00:15:02,400 --> 00:15:05,200 It would probably punch right through the planet's crust. 466 00:15:05,200 --> 00:15:05,840 That's insane. 467 00:15:05,840 --> 00:15:07,960 It's like something out of a superhero comic book. 468 00:15:07,960 --> 00:15:08,520 Yeah. 469 00:15:08,520 --> 00:15:11,080 But what makes neutron stars so dense? 470 00:15:11,080 --> 00:15:12,520 What are they made of? 471 00:15:12,520 --> 00:15:15,720 They're made almost entirely of neutrons, subatomic particles 472 00:15:15,720 --> 00:15:18,480 that are usually found in the nucleus of an atom. 473 00:15:18,480 --> 00:15:22,080 When a massive star collapses, the protons and electrons 474 00:15:22,080 --> 00:15:24,920 in its core are forced together, forming neutrons. 475 00:15:24,920 --> 00:15:27,640 It's like the atoms themselves are being crushed, 476 00:15:27,640 --> 00:15:30,480 transforming into this ultra dense neutron matter. 477 00:15:30,480 --> 00:15:31,120 Precisely. 478 00:15:31,120 --> 00:15:32,320 That's wild. 479 00:15:32,320 --> 00:15:34,960 But it's not just their density that makes neutron stars 480 00:15:34,960 --> 00:15:36,400 so fascinating, right? 481 00:15:36,400 --> 00:15:37,120 Right. 482 00:15:37,120 --> 00:15:38,920 They also spin incredibly fast. 483 00:15:38,920 --> 00:15:41,360 Some rotate hundreds of times per second. 484 00:15:41,360 --> 00:15:44,720 And as they spin, they emit beams of radiation 485 00:15:44,720 --> 00:15:46,160 from their magnetic poles. 486 00:15:46,160 --> 00:15:48,520 So it's like a cosmic lighthouse spinning around 487 00:15:48,520 --> 00:15:50,000 and sending out these beams of light. 488 00:15:50,000 --> 00:15:51,040 That's a great analogy. 489 00:15:51,040 --> 00:15:53,160 And if those beams happen to sweep across Earth, 490 00:15:53,160 --> 00:15:55,000 we see them as pulses of radio waves. 491 00:15:55,000 --> 00:15:56,320 That's why we call them pulsars. 492 00:15:56,320 --> 00:15:56,880 Pulsars. 493 00:15:56,880 --> 00:15:59,720 Those are the objects that send out those incredibly precise 494 00:15:59,720 --> 00:16:00,520 signals, right? 495 00:16:00,520 --> 00:16:01,000 Yes. 496 00:16:01,000 --> 00:16:04,160 I've heard that astronomers use them as cosmic clocks. 497 00:16:04,160 --> 00:16:05,200 Exactly. 498 00:16:05,200 --> 00:16:07,280 The signals from pulsars are so regular 499 00:16:07,280 --> 00:16:10,040 that we can use them to study a wide range of phenomena, 500 00:16:10,040 --> 00:16:13,520 from the nature of gravity to the structure of our galaxy. 501 00:16:13,520 --> 00:16:14,680 That's pretty amazing. 502 00:16:14,680 --> 00:16:16,280 We're using the remnants of dead stars 503 00:16:16,280 --> 00:16:18,160 to unravel the secrets of the universe. 504 00:16:18,160 --> 00:16:18,760 Yeah. 505 00:16:18,760 --> 00:16:22,160 But let's move on to the even more mysterious objects. 506 00:16:22,160 --> 00:16:23,160 Black holes. 507 00:16:23,160 --> 00:16:23,640 Yes. 508 00:16:23,640 --> 00:16:24,680 What exactly are they? 509 00:16:24,680 --> 00:16:26,640 Black holes are readings of spacetime 510 00:16:26,640 --> 00:16:30,440 where gravity is so strong that nothing, not even light, 511 00:16:30,440 --> 00:16:31,400 can escape. 512 00:16:31,400 --> 00:16:32,960 They're the ultimate cosmic traps. 513 00:16:32,960 --> 00:16:35,320 So anything that crosses the event horizon. 514 00:16:35,320 --> 00:16:35,840 Right. 515 00:16:35,840 --> 00:16:38,240 The boundary of a black hole is gone forever. 516 00:16:38,240 --> 00:16:40,120 That's the current understanding. 517 00:16:40,120 --> 00:16:41,480 Once you cross the event horizon, 518 00:16:41,480 --> 00:16:43,200 there's no coming back. 519 00:16:43,200 --> 00:16:45,040 The gravitational pull is so intense 520 00:16:45,040 --> 00:16:47,520 that it warps the fabric of spacetime itself. 521 00:16:47,520 --> 00:16:50,480 That's both terrifying and fascinating. 522 00:16:50,480 --> 00:16:53,360 But if black holes don't emit any light, 523 00:16:53,360 --> 00:16:55,120 how do we even know they exist? 524 00:16:55,120 --> 00:16:57,120 We can't see black holes directly, 525 00:16:57,120 --> 00:16:59,360 but we can detect their presence through their effects 526 00:16:59,360 --> 00:17:00,640 on the surrounding matter. 527 00:17:00,640 --> 00:17:02,840 So we look for clues like detectives 528 00:17:02,840 --> 00:17:04,120 at a cosmic crime scene. 529 00:17:04,120 --> 00:17:05,280 Exactly. 530 00:17:05,280 --> 00:17:08,720 For example, if a black hole is part of a binary star system, 531 00:17:08,720 --> 00:17:10,920 we can observe the companion star orbiting 532 00:17:10,920 --> 00:17:12,440 around an invisible object. 533 00:17:12,440 --> 00:17:14,880 It's like a cosmic dance with a phantom partner. 534 00:17:14,880 --> 00:17:15,400 It is. 535 00:17:15,400 --> 00:17:16,720 What other clues do we look for? 536 00:17:16,720 --> 00:17:19,000 As matter spirals into a black hole, 537 00:17:19,000 --> 00:17:21,680 it gets superheated and emits x-rays, which 538 00:17:21,680 --> 00:17:23,720 we can detect with telescopes. 539 00:17:23,720 --> 00:17:26,600 This is one way we can pinpoint the location of a black hole. 540 00:17:26,600 --> 00:17:28,600 So black holes might be invisible. 541 00:17:28,600 --> 00:17:29,240 Right. 542 00:17:29,240 --> 00:17:32,640 But they leave behind these telltale signs, 543 00:17:32,640 --> 00:17:33,920 like cosmic fingerprints. 544 00:17:33,920 --> 00:17:35,160 Precisely. 545 00:17:35,160 --> 00:17:36,760 And by studying these signs, we're 546 00:17:36,760 --> 00:17:39,600 slowly piecing together the puzzle of black holes 547 00:17:39,600 --> 00:17:41,400 and their role in the universe. 548 00:17:41,400 --> 00:17:43,880 It's incredible how the death of a star 549 00:17:43,880 --> 00:17:46,680 can lead to the creation of such extreme and fascinating 550 00:17:46,680 --> 00:17:47,800 objects. 551 00:17:47,800 --> 00:17:50,440 From neutron stars to black holes, 552 00:17:50,440 --> 00:17:52,760 the universe is full of surprises. 553 00:17:52,760 --> 00:17:54,880 And each of these objects tells a story 554 00:17:54,880 --> 00:17:57,000 about the life and death of stars, 555 00:17:57,000 --> 00:17:59,960 reminding us that the universe is this constantly evolving 556 00:17:59,960 --> 00:18:01,960 and incredibly complex place. 557 00:18:01,960 --> 00:18:03,960 Well, we've covered a lot of ground today, 558 00:18:03,960 --> 00:18:06,640 from the birth of stars in these vast nebulae 559 00:18:06,640 --> 00:18:09,760 to their dramatic deaths and the mind-boggling remnants 560 00:18:09,760 --> 00:18:10,720 they leave behind. 561 00:18:10,720 --> 00:18:12,040 It's been quite a journey. 562 00:18:12,040 --> 00:18:13,240 It really has. 563 00:18:13,240 --> 00:18:15,280 And it's a journey that continues. 564 00:18:15,280 --> 00:18:17,320 As we delve deeper into the cosmos, 565 00:18:17,320 --> 00:18:19,840 we're sure to uncover even more secrets about stars 566 00:18:19,840 --> 00:18:21,080 and the mysteries they hold. 567 00:18:21,080 --> 00:18:22,880 I can't wait to see what we discover next. 568 00:18:22,880 --> 00:18:25,280 Thanks for joining us on this cosmic adventure. 569 00:18:25,280 --> 00:18:27,200 Don't forget to follow and subscribe to Cosmos 570 00:18:27,200 --> 00:18:29,440 at a Pod for more deep dives into the mysteries 571 00:18:29,440 --> 00:18:31,080 of the universe. 572 00:18:31,080 --> 00:18:45,880 Until next time, keep looking up and keep wondering.