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 --> 00:00:31.359 Okay, let's jump right in. For gosh, decades now, the 8 00:00:31.440 --> 00:00:34.880 big question, the one driving so much astronomy, has just 9 00:00:34.960 --> 00:00:38.359 been are we alone? 10 00:00:38.439 --> 00:00:40.920 It's fundamental, isn't it the ultimate question? 11 00:00:41.159 --> 00:00:45.439 Really? And we found thousands of planets out there, exoplanets 12 00:00:45.479 --> 00:00:49.759 since the nineties. But this new one, this super GJA 13 00:00:49.840 --> 00:00:52.920 two fifty one C, it's apparently less than twenty light 14 00:00:53.000 --> 00:00:56.759 years away, and researchers are calling it quote the best 15 00:00:56.840 --> 00:00:59.439 chance of finding life elsewhere in the near future. 16 00:01:00.119 --> 00:01:01.320 It's a pretty bold claim. 17 00:01:01.399 --> 00:01:03.920 It is bold, but there's solid reasoning behind it. It's 18 00:01:03.960 --> 00:01:06.079 generating a lot of excitement, and for good reason. 19 00:01:06.200 --> 00:01:08.200 So today we're doing a deep dive into this. We've 20 00:01:08.200 --> 00:01:11.239 got the announcement details from Penn State researchers and their 21 00:01:11.280 --> 00:01:15.239 international team dated October twenty three, twenty twenty five. Our 22 00:01:15.239 --> 00:01:17.400 goal here is to really impact this for you get 23 00:01:17.400 --> 00:01:19.959 past the headline exactly, not just what they found, but 24 00:01:20.040 --> 00:01:22.439 how they found it, because apparently this took what two 25 00:01:22.519 --> 00:01:23.040 decades of. 26 00:01:23.000 --> 00:01:25.319 Data over twenty years, Yes, a massive effort. 27 00:01:25.439 --> 00:01:28.120 We want to understand why this planet GJ two to 28 00:01:28.159 --> 00:01:31.400 fifty one C is suddenly the prime target, the one 29 00:01:31.400 --> 00:01:33.159 everyone's focusing on for habitability. 30 00:01:33.239 --> 00:01:35.519 It hits a kind of trifecta. Okay, let's start with 31 00:01:35.560 --> 00:01:39.000 the basics. Then the planet itself, GJ two to fifty 32 00:01:39.040 --> 00:01:41.680 one C. It orbits a star called GJ two to 33 00:01:41.680 --> 00:01:42.560 fifty one, a. 34 00:01:42.599 --> 00:01:46.760 Nearby m dwarf star, relatively cool compared to our son, and. 35 00:01:46.719 --> 00:01:49.439 It's a super earth. What does that mean? In practice? 36 00:01:49.480 --> 00:01:52.079 The data says it's almost four times the mass of Earth. 37 00:01:52.280 --> 00:01:56.079 That's the estimate, yes, around four Earth masses. And crucially, 38 00:01:56.280 --> 00:02:01.239 the data strongly suggests it's rocky, like Earth or Venus, 39 00:02:01.760 --> 00:02:02.719 not a gas giant. 40 00:02:02.879 --> 00:02:06.040 Right now, we've found other super earths, haven't we. Finding 41 00:02:06.079 --> 00:02:08.159 a big rocky planet isn't entirely. 42 00:02:07.879 --> 00:02:10.680 New, No, not in itself. We know of quite a few, So. 43 00:02:10.759 --> 00:02:13.000 Why all the buzz about this one? With over five 44 00:02:13.080 --> 00:02:16.560 thousand exoplanets cataloged. Why does GJ two fifty one C 45 00:02:16.719 --> 00:02:17.960 stand out so dramatically. 46 00:02:18.120 --> 00:02:20.080 Well, like I said, it's this combination of factors that 47 00:02:20.120 --> 00:02:24.120 really clicks. Three main things. First it's proximity, Second it's mass, 48 00:02:24.560 --> 00:02:27.080 and third where it sits relative to its star, right 49 00:02:27.159 --> 00:02:30.400 in the habitable zone Goldilock zone exactly. And it's not 50 00:02:30.479 --> 00:02:32.240 just that it ticks these boxes, it's how well it 51 00:02:32.280 --> 00:02:34.599 ticks them, especially when you think about actually starting it 52 00:02:34.639 --> 00:02:35.120 in the future. 53 00:02:35.280 --> 00:02:39.360 Okay, let's break those down. Proximity first, less than twenty 54 00:02:39.439 --> 00:02:43.479 light years you said, that's basically next door astronomically speaking, 55 00:02:43.719 --> 00:02:44.879 Why is that so important? 56 00:02:45.039 --> 00:02:49.120 It's huge for future observation. Think about trying to take 57 00:02:49.120 --> 00:02:52.680 a picture or analyze the light from something incredibly faint. 58 00:02:53.319 --> 00:02:56.319 The closer it is, the more light, the more photons 59 00:02:56.360 --> 00:02:57.919 we can collect with our telescopes. 60 00:02:58.000 --> 00:03:00.039 Ah, so the signal is stronger. 61 00:02:59.719 --> 00:03:03.400 Much stronger if we want to analyze its atmosphere, which 62 00:03:03.439 --> 00:03:06.360 is the ultimate goal here. Being at twenty light years 63 00:03:06.400 --> 00:03:09.759 instead of say one hundred light years makes an enormous difference. 64 00:03:09.759 --> 00:03:12.479 It brings it within reach of the next generation of telescopes. 65 00:03:12.919 --> 00:03:15.000 The feasibility just sty rockets. 66 00:03:15.120 --> 00:03:17.080 Okay, that makes a lot of sense, cuts down the 67 00:03:17.159 --> 00:03:20.039 challenge for the future tech. Now, the mass nearly four 68 00:03:20.080 --> 00:03:24.159 times Earth. You mentioned that combined with being rocky is significant. 69 00:03:24.360 --> 00:03:27.479 How does that affect its potential for life? Is bigger? Better? 70 00:03:27.639 --> 00:03:30.159 Well up to a point. Yes, a planet with four 71 00:03:30.199 --> 00:03:33.840 times Earth's mass, assuming its rocky, has significantly stronger gravity. 72 00:03:34.159 --> 00:03:37.199 And that stronger gravity is key for holding onto an 73 00:03:37.199 --> 00:03:42.240 atmosphere over billions of years. Earth loses some atmosphere to space. 74 00:03:42.759 --> 00:03:46.039 A super Earth can cling onto a thicker, more substantial 75 00:03:46.080 --> 00:03:47.639 atmosphere much more easily. 76 00:03:47.719 --> 00:03:51.080 So it's potentially better at keeping the conditions stable, protecting 77 00:03:51.120 --> 00:03:52.719 any surface water exactly. 78 00:03:53.159 --> 00:03:56.919 Better atmosphere pretension means a better chance of maintaining stable 79 00:03:56.919 --> 00:04:00.479 temperatures and shielding the surface from harmful stellar radiation or 80 00:04:00.520 --> 00:04:03.960 particle wins. It's a big plus for long term habitability. 81 00:04:04.199 --> 00:04:09.919 Okay. Proximity check, mass and potential atmosphere check. Now the 82 00:04:09.960 --> 00:04:12.800 big one, the habitable zone. Can you define that for 83 00:04:12.879 --> 00:04:15.080 us again? The source mentioned liquid water. 84 00:04:15.439 --> 00:04:18.240 Yeah, the astronomer suvrathmahadave and put it nicely. He defined 85 00:04:18.279 --> 00:04:20.399 it as the right distance from its star that liquid 86 00:04:20.480 --> 00:04:21.759 water could exist on its surface. 87 00:04:21.759 --> 00:04:24.360 If it has the right atmosphere, that qualifier seems important. 88 00:04:24.519 --> 00:04:27.600 It's critical. Being in the zone doesn't guarantee oceans. It 89 00:04:27.680 --> 00:04:31.120 just means the temperature range based on the star's energy 90 00:04:31.160 --> 00:04:34.920 output is theoretically compatible with liquid water. If the atmosphereic 91 00:04:34.920 --> 00:04:38.800 pressure is sufficient, too thin an atmosphere water boils away 92 00:04:38.879 --> 00:04:42.360 or freezes too thick, you might get a runaway greenhouse effect. 93 00:04:42.480 --> 00:04:45.040 So the zone depends on the star. Right, GJ two 94 00:04:45.079 --> 00:04:47.680 to fifty one is a cooler M dwarf star. Does 95 00:04:47.680 --> 00:04:49.639 that mean the habitable zone is different than ours? 96 00:04:49.680 --> 00:04:53.439 Absolutely? M dwarfs are much dimmer and cooler than our 97 00:04:53.480 --> 00:04:56.319 G type sun. So for a planet to receive enough 98 00:04:56.399 --> 00:04:59.160 warmth for liquid water, it needs to orbit much much 99 00:04:59.240 --> 00:05:00.199 closer to the star. 100 00:05:00.079 --> 00:05:02.360 A closer than mercury is to our Sun. 101 00:05:02.519 --> 00:05:05.399 Oh often, yes, In this case, GJ two hundred and 102 00:05:05.399 --> 00:05:08.160 fifty one c orbits its star every fifty four days. 103 00:05:08.319 --> 00:05:10.680 Compare that to Earth's three hundred and sixty five days. 104 00:05:10.800 --> 00:05:13.000 It's huddled much closer to its star to get that 105 00:05:13.160 --> 00:05:14.120 just right temperature. 106 00:05:14.199 --> 00:05:16.879 So fifty four days that's the orbital period that puts 107 00:05:16.879 --> 00:05:18.879 its smack in the middle of that thermal sweet spot 108 00:05:18.920 --> 00:05:20.040 for GJ two to fifty one. 109 00:05:20.120 --> 00:05:22.560 That's what the calculations show. It's receiving the right amount 110 00:05:22.560 --> 00:05:25.240 of energy flux from the star to potentially allow liquid water, 111 00:05:25.480 --> 00:05:29.199 assuming other conditions like that atmosphere are met. It avoids 112 00:05:29.199 --> 00:05:30.639 being fried or frozen solid. 113 00:05:30.920 --> 00:05:34.839 And that potential for liquid water is really the cornerstone 114 00:05:34.959 --> 00:05:37.040 of our search for life as we know it isn't it. 115 00:05:37.040 --> 00:05:40.120 It focuses the search find the water, find the life, 116 00:05:40.439 --> 00:05:41.839 or at least the potential for it. 117 00:05:41.839 --> 00:05:45.240 It's the primary driver. Yes, life as we understand it 118 00:05:45.319 --> 00:05:49.680 fundamentally requires liquid water. So finding planets in the habitable zone, 119 00:05:49.759 --> 00:05:53.279 especially around common stars like M dwarfs, gives us the 120 00:05:53.319 --> 00:05:56.439 best statistical chance. These are our prime candidates. 121 00:05:56.480 --> 00:05:58.480 And you mentioned M dwarfs are the most common stars 122 00:05:58.560 --> 00:05:58.959 by far. 123 00:05:59.399 --> 00:06:02.519 They make a maybe seventy seventy five percent of all 124 00:06:02.560 --> 00:06:05.240 stars in the Milky Way, So if habitable planets can 125 00:06:05.279 --> 00:06:07.839 form around them, the number of potential habitats in the 126 00:06:07.839 --> 00:06:09.079 galaxy could be enormous. 127 00:06:09.120 --> 00:06:11.480 Okay, So GJ two fifty one c orbits this common 128 00:06:11.519 --> 00:06:13.519 type of star, does it have any neighbors? Are there 129 00:06:13.519 --> 00:06:14.759 other planets in that system? 130 00:06:15.079 --> 00:06:18.079 Yes, there is another known planet, GJ two fifty one B. 131 00:06:18.240 --> 00:06:20.959 It's an inner planet much closer to the star. It 132 00:06:21.040 --> 00:06:25.279 orbits really quickly every fourteen days. And actually confirming GJ 133 00:06:25.399 --> 00:06:28.399 two fifty one C the new discovery really depended on 134 00:06:28.519 --> 00:06:31.839 understanding planet B firstesa well, the team had to use 135 00:06:31.920 --> 00:06:35.000 all their data, especially that long twenty year baseline, to 136 00:06:35.079 --> 00:06:38.959 precisely measure the gravitational pull the wobble caused by the 137 00:06:38.959 --> 00:06:41.800 known inner planet GJ two to fifty one B. They 138 00:06:41.839 --> 00:06:43.920 had to perfectly account for its signals. 139 00:06:43.600 --> 00:06:45.199 So we're subtracted out exactly. 140 00:06:45.560 --> 00:06:48.279 Only after they completely modeled and removed the effect of 141 00:06:48.279 --> 00:06:51.600 the fourteen day planet could they confidently detect the remaining 142 00:06:52.079 --> 00:06:55.839 more subtle signal the fifty four day wobble caused by 143 00:06:55.879 --> 00:06:59.040 the new more massive planet GJ two to fifty one 144 00:06:59.120 --> 00:07:01.240 C further out in the habitable zone. 145 00:07:01.279 --> 00:07:04.519 Wow, So finding the second planet required first getting an 146 00:07:04.560 --> 00:07:06.000 even better handle on the first one. 147 00:07:06.040 --> 00:07:09.560 Precisely, it shows how interconnected these detections can be within 148 00:07:09.600 --> 00:07:10.439 a single system. 149 00:07:10.560 --> 00:07:13.560 That brings us perfectly to the how because finding this 150 00:07:13.800 --> 00:07:16.399 wasn't simple. It wasn't like someone just pointed a telescope 151 00:07:16.439 --> 00:07:17.160 and saize. 152 00:07:16.920 --> 00:07:18.720 Well, Heavens no, not at all. 153 00:07:18.800 --> 00:07:22.839 This discovery really underscores the sheer persistence needed in this field. 154 00:07:22.920 --> 00:07:26.800 We're talking two decades, over twenty years of observations from 155 00:07:26.839 --> 00:07:28.240 telescopes all around the world. 156 00:07:28.439 --> 00:07:32.480 It's a testament to long term scientific vision and frankly funding, 157 00:07:33.040 --> 00:07:36.879 keeping instruments running, collecting data night after night, year after year, 158 00:07:37.240 --> 00:07:39.759 looking for these incredibly tiny signals. 159 00:07:39.800 --> 00:07:41.959 What are they actually looking for in that data? How 160 00:07:42.000 --> 00:07:43.600 do you find a planet you can't see? 161 00:07:44.120 --> 00:07:48.399 They use the workhorce method for finding many exoplanets, especially 162 00:07:48.480 --> 00:07:53.519 older discoveries, the radial velocity method, or the wobble method. 163 00:07:53.199 --> 00:07:54.959 As it's sometimes called the Wobble method. 164 00:07:55.199 --> 00:07:58.120 It relies on gravity. Even though the star is vastly 165 00:07:58.199 --> 00:08:00.879 more massive the planet's gravit but he still tugs on 166 00:08:00.920 --> 00:08:03.560 the star just a tiny bit as it orbits. It 167 00:08:03.600 --> 00:08:06.439 makes the star perform a little circular or elliptical dance. 168 00:08:06.639 --> 00:08:08.759 So the star itself moves, yes. 169 00:08:08.879 --> 00:08:11.439 It wabbles around the common center of mass between it 170 00:08:11.519 --> 00:08:14.519 and the planet. It's a very small movement for a 171 00:08:14.519 --> 00:08:16.959 planet like GJ two fifty one C. We might be 172 00:08:17.000 --> 00:08:19.319 talking about the star moving back and forth at the 173 00:08:19.360 --> 00:08:21.800 speed of a slow walk like one or two meters 174 00:08:21.839 --> 00:08:22.279 per second. 175 00:08:22.319 --> 00:08:25.240 Okay, hold on measuring a star moving at walking speed 176 00:08:25.920 --> 00:08:28.600 from twenty light years away. How on earth do you 177 00:08:28.639 --> 00:08:29.879 do that? That sounds impossible. 178 00:08:30.160 --> 00:08:33.159 It sounds impossible, but it's done using the Doppler effect 179 00:08:33.159 --> 00:08:36.440 on light. It's the same principle that makes an ambulance 180 00:08:36.480 --> 00:08:39.480 siren sound higher pitched when it's coming towards you and 181 00:08:39.559 --> 00:08:42.799 lower when it's moving away. Okay, As the star wobbles, 182 00:08:42.879 --> 00:08:45.159 it moves slightly towards us, and it's little dance, and 183 00:08:45.200 --> 00:08:48.399 then slightly away from us. When it moves towards us, 184 00:08:48.600 --> 00:08:51.720 it's light waves get compressed just a tiny bit, shifting 185 00:08:51.720 --> 00:08:53.799 the light towards the blue end of the spectrum a 186 00:08:53.840 --> 00:08:56.840 blue shiss, exactly, And when it moves away, the light 187 00:08:56.879 --> 00:09:00.039 waves get stretched slightly, shifting towards the red end of 188 00:08:59.879 --> 00:09:01.600 the spectrum, a red shift. 189 00:09:01.879 --> 00:09:05.240 So they're looking for these minuscule periodic shifts in the 190 00:09:05.279 --> 00:09:05.720 color of. 191 00:09:05.639 --> 00:09:10.000 The starlight, precisely, tiny, tiny cyclical shifts back and forth 192 00:09:10.039 --> 00:09:13.039 between blue and red. The timing of those shifts tells 193 00:09:13.120 --> 00:09:16.440 us the planet's orbital period fifty four days in this case, 194 00:09:16.720 --> 00:09:18.600 and the size of the shift tells us how much 195 00:09:18.600 --> 00:09:21.120 the star is moving, which lets us calculate the planet's 196 00:09:21.159 --> 00:09:21.960 minimum mass. 197 00:09:22.159 --> 00:09:29.519 Wow, the precision required must be just astronomical, literally absolutely exquisite. 198 00:09:29.960 --> 00:09:33.600 Measuring velocities of a meter per second requires incredibly stable 199 00:09:33.639 --> 00:09:37.039 instruments called spectrographs, and that's where the key piece of 200 00:09:37.120 --> 00:09:40.639 new technology comes into this story, the Habitable Zone planet 201 00:09:40.639 --> 00:09:42.120 Finder or HPF. 202 00:09:42.399 --> 00:09:44.960 The HPF this was led by the Penn State team. 203 00:09:45.080 --> 00:09:49.360 Yes, it's a high precision spectrograph specifically designed to achieve 204 00:09:49.399 --> 00:09:52.840 these meter per second measurements, but with a crucial focus. 205 00:09:52.960 --> 00:09:53.559 What's a focus? 206 00:09:53.600 --> 00:09:55.799 It operates in the near infrared part of the spectrum. 207 00:09:55.840 --> 00:09:58.039 Think of it is a very complex prism that works 208 00:09:58.039 --> 00:10:01.840 with light frequencies beyond what our eyes can see as red. 209 00:10:01.960 --> 00:10:04.000 And it's attached to a big telescope. 210 00:10:03.600 --> 00:10:06.200 A very big one. It's fixed to the Hobby Eberly 211 00:10:06.279 --> 00:10:10.159 Telescope at McDonald Observatory in Texas. And its name says 212 00:10:10.200 --> 00:10:13.879 it all Habitable Zone planet Finder. It was purpose built 213 00:10:13.879 --> 00:10:17.080 for exactly this kind of work, finding potentially habitable planets 214 00:10:17.120 --> 00:10:18.519 around nearby cool stars. 215 00:10:18.840 --> 00:10:23.120 Why near infrared? Why is that specific wavelength range so 216 00:10:23.320 --> 00:10:26.759 important for these cool m dwarf stars like GJ two 217 00:10:26.759 --> 00:10:27.399 meter fifty one. 218 00:10:28.080 --> 00:10:31.080 Two main reasons. First, M dwarfs are cool, so they 219 00:10:31.120 --> 00:10:34.279 actually emit most of their light in the near infrared, 220 00:10:34.600 --> 00:10:37.879 not visible light like arsun So, if you want the 221 00:10:37.960 --> 00:10:41.559 strongest possible signal from the star to analyze, you look 222 00:10:41.600 --> 00:10:42.480 where it's brightest. 223 00:10:42.600 --> 00:10:44.039 Okay, fall of the white right. 224 00:10:44.360 --> 00:10:47.360 But the second reason is perhaps even more critical for precision. 225 00:10:48.080 --> 00:10:51.039 Looking in the near infrared helps to mitigate the star's 226 00:10:51.120 --> 00:10:52.720 own activity. It's noise. 227 00:10:52.960 --> 00:10:55.759 Ah, so the starlight itself isn't perfectly steady. 228 00:10:56.080 --> 00:10:58.279 Far from it. Especially with M dwarfs, they can be 229 00:10:58.600 --> 00:11:03.120 quite active starspots flares. This creates signals that can mimic 230 00:11:03.159 --> 00:11:07.240 a planet's wobble, especially invisible light. But this stellar noise 231 00:11:07.320 --> 00:11:11.080 tends to be less problematic, less confusing in the near infrared. 232 00:11:11.360 --> 00:11:14.080 Interesting, so the HPF is designed not just for precision, 233 00:11:14.480 --> 00:11:17.320 but to look through a sort of quieter window in 234 00:11:17.320 --> 00:11:18.120 the star's lights. 235 00:11:18.159 --> 00:11:20.720 That's a great way to put it. Zufrath Mahindevun mentioned 236 00:11:20.720 --> 00:11:23.759 this was a specific goal. The hpf's strength is detecting 237 00:11:23.840 --> 00:11:26.600 these precise shifts in the near infrared, where the star's 238 00:11:26.639 --> 00:11:30.320 intrinsic variability has less impact. On the measurements. It helps 239 00:11:30.360 --> 00:11:33.000 separate the wheat from the chaff, the real planet signal 240 00:11:33.000 --> 00:11:33.960 from the stellar jitter. 241 00:11:34.200 --> 00:11:37.080 So let's recap the detection sequence. They had the twenty 242 00:11:37.120 --> 00:11:40.840 plus years of data from various older instruments historical baseline YES, 243 00:11:40.919 --> 00:11:43.519 which helped map out the effect of the known inner 244 00:11:43.559 --> 00:11:46.759 planet GJ two to fifty one. Then they brought in 245 00:11:46.799 --> 00:11:49.799 the HPF looking at that quieter near infrared window. 246 00:11:49.879 --> 00:11:52.879 Correct they combine the long term data with the new 247 00:11:53.120 --> 00:11:54.799 high precision HPF. 248 00:11:54.399 --> 00:11:56.519 Measurements and ones they counted for planet. 249 00:11:56.200 --> 00:12:00.720 B a second clear periodic signal popped out, a wobble 250 00:12:00.799 --> 00:12:04.240 repeating every fifty four days, and the amplitude of that 251 00:12:04.320 --> 00:12:07.480 wobble how fast the star was moving indicated a much 252 00:12:07.519 --> 00:12:10.679 more massive object was responsible, something around four times the 253 00:12:10.720 --> 00:12:13.240 massive Earth that was GJ two fifty one C. 254 00:12:13.840 --> 00:12:16.480 But they didn't stop there, did they. They wanted confirmation. 255 00:12:16.720 --> 00:12:19.759 Always good practice and science. They use another cutting edge instrument, 256 00:12:19.759 --> 00:12:21.879 also built by Penn State researchers called. 257 00:12:21.879 --> 00:12:23.200 N E an EID. 258 00:12:23.519 --> 00:12:27.080 YES, it's attached to a telescope at Kitpeak National Observatory 259 00:12:27.120 --> 00:12:30.000 in Arizona. Now, any EID is different from HPF. It's 260 00:12:30.039 --> 00:12:32.759 optimized for visible light like what our ies see. 261 00:12:32.799 --> 00:12:35.080 So they checked the signal with two different state of 262 00:12:35.080 --> 00:12:37.039 the art instruments looking at different kinds. 263 00:12:36.840 --> 00:12:40.600 Of light exactly, and the fact that both HPF in 264 00:12:40.639 --> 00:12:44.440 the near infrared and knee eyed in the visible independently 265 00:12:44.480 --> 00:12:48.360 confirmed that same fifty four day wobble gave them very 266 00:12:48.399 --> 00:12:51.120 high confidence that was a real planetary signal, not some 267 00:12:51.279 --> 00:12:53.879 instrumental glitch or weird stellar activity. 268 00:12:54.039 --> 00:12:56.279 That cross validation must have been key. 269 00:12:56.159 --> 00:13:00.679 Absolutely crucial. It demonstrated the signal was robust across different wavelengths. 270 00:13:01.120 --> 00:13:03.919 Corey Beard, one of the authors, really emphasize this point. 271 00:13:03.919 --> 00:13:07.360 They're using cutting edge tech and cutting edge analysis methods. 272 00:13:07.720 --> 00:13:10.360 It wasn't just one magic instrument. It was the synergy 273 00:13:10.559 --> 00:13:14.440 twenty years of data plus hpf's near infrared precision plus 274 00:13:14.559 --> 00:13:16.200 nee'd's visible light conformation. 275 00:13:16.480 --> 00:13:19.240 That paints a picture of just how rigorous this process 276 00:13:19.279 --> 00:13:21.360 has to be. Yeah, Okay, so the signal is there, 277 00:13:21.440 --> 00:13:24.600 it's confirmed, But you mentioned stellar activity, the star's own 278 00:13:24.639 --> 00:13:28.039 noise being a major challenge. Even with HPF looking at 279 00:13:28.039 --> 00:13:31.240 the near and for red, that doesn't completely eliminate the problem, 280 00:13:31.279 --> 00:13:31.559 does it. 281 00:13:31.639 --> 00:13:34.120 No, it mitigates it, but doesn't eliminate it. This is 282 00:13:34.159 --> 00:13:36.879 honestly where some of the most sophisticated work happens now. 283 00:13:37.039 --> 00:13:40.360 It moves beyond just building better instruments into the realm 284 00:13:40.399 --> 00:13:43.200 of advanced data science and computational. 285 00:13:42.519 --> 00:13:44.679 Modeling fighting the noise pretty much. 286 00:13:44.840 --> 00:13:49.159 Astronomers widely agree that disentangling the tiny planetary signal from 287 00:13:49.159 --> 00:13:52.399 the star's own weather is the biggest hurdle, especially for 288 00:13:52.480 --> 00:13:54.600 finding small Earth sized planets. 289 00:13:55.000 --> 00:13:57.200 How does the star's weather mimic a planet? You mentioned 290 00:13:57.200 --> 00:13:58.320 star spots. 291 00:13:58.080 --> 00:14:01.200 Right, Imagine a large cool sur spot on the surface 292 00:14:01.200 --> 00:14:04.840 of the star. As the star rotates, that spot comes 293 00:14:04.840 --> 00:14:07.600 into view, crosses the star's face, and then rotates out 294 00:14:07.639 --> 00:14:10.840 of you. Okay, that spot changes the overall light we 295 00:14:10.879 --> 00:14:13.480 receive from the star. It can slightly alter the measured 296 00:14:13.519 --> 00:14:16.039 color or brightness in a periodic way that lines up 297 00:14:16.080 --> 00:14:19.279 with the star's rotation period, and that periodic signal can 298 00:14:19.320 --> 00:14:21.720 look very similar to the Doppler shift caused by an 299 00:14:21.799 --> 00:14:22.480 orbiting planet. 300 00:14:22.559 --> 00:14:24.559 The falls positive exactly. 301 00:14:24.360 --> 00:14:26.360 A signal that looks like a planet but is just 302 00:14:26.399 --> 00:14:29.879 the star itself. Changing m dwarfs in particular can be 303 00:14:30.000 --> 00:14:34.600 magnetically active, making this rotational modulation noise a serious problem. 304 00:14:35.320 --> 00:14:38.480 Mad Divin used that great phrase, trying to find signals 305 00:14:38.519 --> 00:14:42.279 in a froffing magnetospheric cauldron of a star surface. 306 00:14:42.000 --> 00:14:44.200 That paints a vivid picture. So how do they tell 307 00:14:44.240 --> 00:14:46.519 the difference? How do they know they're hearing the planet's 308 00:14:46.519 --> 00:14:48.879 whisper and not just the star's cauldron bubbling. 309 00:14:49.120 --> 00:14:52.840 The key insight relies on color or wavelength. Remember how 310 00:14:52.840 --> 00:14:55.759 the planet's gravitational wobble pulls the entire star. 311 00:14:55.879 --> 00:14:58.360 Yeah, the whole star moves slightly back and forth. 312 00:14:58.440 --> 00:15:01.279 Because the whole star is moving, the Doppler shift it 313 00:15:01.399 --> 00:15:03.840 causes should be the same regardless of what color light 314 00:15:03.879 --> 00:15:06.399 you look at. The shift in blue light should match 315 00:15:06.440 --> 00:15:08.639 the shift in red light should match the shift in 316 00:15:08.720 --> 00:15:13.360 infrared light. It's achromatic, meaning colorless or independent of color. 317 00:15:13.440 --> 00:15:15.919 Okay, the real wobble affects all colors. 318 00:15:15.600 --> 00:15:20.519 Equally, but stellar activity, like star spots, is chromatic. A 319 00:15:20.639 --> 00:15:24.240 cool star spot emits less light, especially at certain wavelength, 320 00:15:24.679 --> 00:15:27.679 so the full signal it creates might be stronger in 321 00:15:27.720 --> 00:15:30.240 blue light and weaker in red light, or vice versa. 322 00:15:30.799 --> 00:15:33.399 It depends on the temperature difference between the spot and the. 323 00:15:33.360 --> 00:15:36.000 Rest of the star. Ah, so they can use the 324 00:15:36.039 --> 00:15:38.879 color information from the spectrographs like HPF and the EID 325 00:15:39.200 --> 00:15:40.320 as a diagnostic tool. 326 00:15:40.399 --> 00:15:44.559 Precisely, they use incredibly sophisticated computer models. These aren't just 327 00:15:44.600 --> 00:15:48.679 simple filters. There are complex algorithms, often involving machine learning. 328 00:15:49.240 --> 00:15:52.879 These models analyze how the signal strength changes across all 329 00:15:52.919 --> 00:15:56.279 the different wavelengths the spectrograph measures. If the signal looks 330 00:15:56.320 --> 00:15:59.000 different in different colors, the model flags it as a 331 00:15:59.120 --> 00:16:02.879 likely stellar active. If the signal is consistent across all 332 00:16:02.879 --> 00:16:06.440 colors achromatic, it's much more likely to be a genuine planet. 333 00:16:07.039 --> 00:16:09.840 So it's not just collecting the data, it's building custom 334 00:16:09.960 --> 00:16:12.120 software to interpret it based on the physics of the 335 00:16:12.120 --> 00:16:13.799 star and the planet exactly. 336 00:16:14.279 --> 00:16:16.759 Eric Ford at Penn State emphasized this. He said it 337 00:16:16.799 --> 00:16:20.399 required customizing the data science methods for the specific needs 338 00:16:20.440 --> 00:16:23.879 of this star and combination of instruments. It wasn't an 339 00:16:23.919 --> 00:16:26.960 off the shelf solution. They had to tailor their analysis 340 00:16:27.000 --> 00:16:30.559 pipeline specifically for GJ two fifty one and the data 341 00:16:30.600 --> 00:16:32.720 coming from HPF and other telescopes. 342 00:16:32.879 --> 00:16:35.639 Custom data science for a specific star system, And what 343 00:16:35.720 --> 00:16:37.159 kind of complexity are we talking about? Is it like 344 00:16:37.240 --> 00:16:39.080 running massive simulations. 345 00:16:38.600 --> 00:16:43.399 It involves complex statistical frameworks. These models have to simultaneously 346 00:16:43.440 --> 00:16:46.679 account for the known planet B, the suspected planet C, 347 00:16:47.120 --> 00:16:50.639 the star's rotation period, the typical behavior of star spots 348 00:16:50.639 --> 00:16:53.200 on this specific star which they learned from the long 349 00:16:53.279 --> 00:16:56.840 term data, plus the noise characteristics of each telescope use 350 00:16:56.919 --> 00:17:00.000 over twenty years. It's a massive computational puzzle. 351 00:17:00.240 --> 00:17:03.000 That twenty year baseline must be gold for that kind. 352 00:17:02.799 --> 00:17:06.720 Of modeling invaluable. It allows the models to distinguish between 353 00:17:06.839 --> 00:17:11.279 short term stellar weather and the consistent long term periodicity 354 00:17:11.359 --> 00:17:14.480 of a real planet's orbit. It lets them see beyond 355 00:17:14.519 --> 00:17:18.400 the froft to the underlying gravitational signal. This really highlights 356 00:17:18.440 --> 00:17:23.319 how modern astrophysics relies heavily on collaboration between observers, instrument builders, 357 00:17:23.319 --> 00:17:25.160 and computational scientists. 358 00:17:24.759 --> 00:17:27.039 And incredible fusion of skills. Okay, so they've done the 359 00:17:27.079 --> 00:17:30.680 hard yards, two decades of data, cutting edge instruments, bespoke 360 00:17:30.839 --> 00:17:34.119 data science to beat the noise. They've confirmed GJ two 361 00:17:34.160 --> 00:17:36.680 to fifty one C. It's it's four Earth masses, it's 362 00:17:36.720 --> 00:17:39.240 in the habitable zone. But we still can't see it, right, 363 00:17:39.240 --> 00:17:40.920 This is all still based on the star's wabble. 364 00:17:41.039 --> 00:17:44.720 That's correct. Radial velocity is an indirect detection method. It 365 00:17:44.759 --> 00:17:47.960 tells us the planet is there, its orbit, its minimum mass, 366 00:17:48.359 --> 00:17:51.240 but it doesn't give us a picture. It doesn't directly 367 00:17:51.279 --> 00:17:54.039 tell us if it has an atmosphere, let alone what's 368 00:17:54.079 --> 00:17:54.359 in it? 369 00:17:54.720 --> 00:17:58.160 Which brings us to the future. Why is this planet 370 00:17:58.559 --> 00:18:02.000 detected indirectly? Causing so much excitement for the next steps? 371 00:18:02.519 --> 00:18:06.119 Madavin mentioned direct imaging is impossible now, but they're looking ahead. 372 00:18:06.599 --> 00:18:10.000 Yes, and its status as a prime target comes back 373 00:18:10.039 --> 00:18:13.079 to that proximity being less than twenty light years away 374 00:18:13.160 --> 00:18:15.240 makes it one of the absolute best candidates we have 375 00:18:15.319 --> 00:18:19.680 for the next major phase searching for atmospheric biosignatures. 376 00:18:18.880 --> 00:18:20.519 Signs of life in its atmosphere. 377 00:18:20.640 --> 00:18:23.400 Potentially Yes, The sources say it's one of the best 378 00:18:23.400 --> 00:18:25.559 shots we might have in the next five to ten 379 00:18:25.640 --> 00:18:28.680 years to actually find chemical evidence of life beyond Earth, 380 00:18:29.079 --> 00:18:32.480 and its closeness is what makes that timeframe plausible. 381 00:18:32.160 --> 00:18:35.480 Because analyzing an atmosphere requires even more light than just 382 00:18:35.519 --> 00:18:37.400 detecting the wobble, vastly more. 383 00:18:37.799 --> 00:18:40.200 You need to not only detect the faint light from 384 00:18:40.200 --> 00:18:43.519 the planet itself or light filtered through its atmosphere, but 385 00:18:43.599 --> 00:18:45.799 you need to spread that light out into a spectrum 386 00:18:45.839 --> 00:18:49.240 to see what chemicals are present. That requires collecting a 387 00:18:49.359 --> 00:18:53.200 huge number of photons. Being nearby helps enormously. 388 00:18:53.519 --> 00:18:55.680 So what tech do we need for that? If current 389 00:18:55.720 --> 00:18:57.359 telescopes can't do it, what's coming. 390 00:18:57.480 --> 00:19:01.400 We're talking about the next generation of behemoths, specifically the 391 00:19:01.559 --> 00:19:04.720 upcoming thirty meter class ground based. 392 00:19:04.440 --> 00:19:07.119 Telescopes thirty meters that's huge. 393 00:19:06.920 --> 00:19:11.359 Enormous telescopes like the European Extremely Large Telescope the ELT 394 00:19:11.680 --> 00:19:15.720 or the Giant Magellan Telescope GMT. These represent a quantum 395 00:19:15.839 --> 00:19:18.839 leap in light gathering power compared to today's best. 396 00:19:18.839 --> 00:19:20.559 And these will be able to actually take a picture 397 00:19:20.640 --> 00:19:21.960 of GJ too fifty one C. 398 00:19:22.240 --> 00:19:27.279 That's the expectation. Using highly advanced optics, including instruments called coronagraphs, 399 00:19:27.279 --> 00:19:29.720 which block out the overwhelming layer of the host star, 400 00:19:29.960 --> 00:19:33.160 they should be able to directly image nearby rocky planets 401 00:19:33.200 --> 00:19:36.079