WEBVTT FILE 1 00:00:09.551 --> 00:00:12.303 This is an object called V838 2 00:00:12.345 --> 00:00:14.764 Monocerotis, or V838 Mon, 3 00:00:14.764 --> 00:00:16.057 and it's a series 4 00:00:16.057 --> 00:00:17.892 of images of the same object 5 00:00:17.892 --> 00:00:19.811 that are taken over 6 00:00:19.811 --> 00:00:22.355 about a half a year or so in 2002. 7 00:00:23.773 --> 00:00:24.941 So, we see the central object 8 00:00:24.941 --> 00:00:25.859 here is the same 9 00:00:25.859 --> 00:00:27.610 in each of the four images. 10 00:00:27.610 --> 00:00:29.946 But what is immediately apparent is that 11 00:00:30.238 --> 00:00:32.407 there's an expanding 12 00:00:32.532 --> 00:00:34.159 brightness around it. 13 00:00:34.159 --> 00:00:36.244 So what was first thought would be that, 14 00:00:36.244 --> 00:00:37.537 wow, we've got this gas cloud 15 00:00:37.537 --> 00:00:39.039 that is just spewing away 16 00:00:39.039 --> 00:00:39.998 from this object, 17 00:00:39.998 --> 00:00:40.957 but it was spewing away 18 00:00:40.957 --> 00:00:43.209 at incredibly fast speeds. 19 00:00:43.460 --> 00:00:45.128 What is actually happening here, 20 00:00:45.128 --> 00:00:46.254 instead of that gas 21 00:00:46.254 --> 00:00:48.381 itself being in motion 22 00:00:48.381 --> 00:00:50.425 and causing that expansion 23 00:00:50.425 --> 00:00:52.218 is something called a light echo. 24 00:00:52.218 --> 00:00:53.678 So just like you hear an echo 25 00:00:53.678 --> 00:00:56.014 with sound waves, as some sound waves 26 00:00:56.014 --> 00:00:57.515 come directly towards you, 27 00:00:57.515 --> 00:00:59.142 you hear the main source of sound. 28 00:00:59.142 --> 00:01:01.061 But then as others bounce off walls 29 00:01:01.061 --> 00:01:02.771 and come to you a little bit later, 30 00:01:02.771 --> 00:01:04.355 that's where the echo comes from. 31 00:01:04.355 --> 00:01:05.648 The same thing is happening 32 00:01:05.648 --> 00:01:07.400 with light in this image. 33 00:01:07.400 --> 00:01:08.651 We're seeing some of that light 34 00:01:08.651 --> 00:01:09.944 coming directly towards us. 35 00:01:09.944 --> 00:01:10.653 We're seeing that 36 00:01:10.653 --> 00:01:12.739 at the time that we receive it. 37 00:01:12.739 --> 00:01:13.990 But some of the rest of the light 38 00:01:13.990 --> 00:01:17.077 is actually bouncing off material around 39 00:01:17.160 --> 00:01:18.703 that binary in the center. 40 00:01:18.703 --> 00:01:19.537 It bounces off it, 41 00:01:19.537 --> 00:01:21.039 and then it comes to us. 42 00:01:21.039 --> 00:01:22.791 That's the light echo. 43 00:01:22.791 --> 00:01:24.834 And so each one of those 44 00:01:24.834 --> 00:01:25.752 succeeding images 45 00:01:25.752 --> 00:01:27.253 where we see this shell 46 00:01:27.253 --> 00:01:28.963 further and further from the center 47 00:01:28.963 --> 00:01:30.548 is actually that light echo 48 00:01:30.548 --> 00:01:32.717 coming to us later in time. 49 00:01:32.717 --> 00:01:33.968 So we're actually basically 50 00:01:33.968 --> 00:01:35.595 taking a CAT scan 51 00:01:35.595 --> 00:01:39.015 of the material around that central star. 52 00:01:39.307 --> 00:01:41.226 There's still a lot of mystery 53 00:01:41.226 --> 00:01:42.018 surrounding 54 00:01:42.018 --> 00:01:43.978 where that material came from. 55 00:01:43.978 --> 00:01:45.396 Is it being blown off 56 00:01:45.396 --> 00:01:47.232 by these hot, young, 57 00:01:47.232 --> 00:01:48.399 energetic stars 58 00:01:48.399 --> 00:01:50.443 as a process of their star formation? 59 00:01:51.236 --> 00:01:53.238 One of the coolest possibilities 60 00:01:53.238 --> 00:01:54.447 is that one of these stars 61 00:01:54.447 --> 00:01:55.698 actually engulfed 62 00:01:55.698 --> 00:01:58.159 a giant planet in its orbit. 63 00:01:58.159 --> 00:02:00.078 So like a giant planet, like many times 64 00:02:00.078 --> 00:02:01.871 the mass of Jupiter could be in orbit 65 00:02:01.871 --> 00:02:05.250 very close to this very hot, large star. 66 00:02:05.500 --> 00:02:06.793 And the tidal forces 67 00:02:06.793 --> 00:02:08.253 and the energy dissipation 68 00:02:08.253 --> 00:02:09.295 could have been acting on it 69 00:02:09.295 --> 00:02:10.547 in such a way that that now 70 00:02:10.547 --> 00:02:11.923 massive planet 71 00:02:11.923 --> 00:02:13.383 is losing energy, 72 00:02:13.383 --> 00:02:14.592 spinning more rapidly 73 00:02:14.592 --> 00:02:15.385 and closer 74 00:02:15.385 --> 00:02:16.469 to one of those stars, 75 00:02:16.469 --> 00:02:18.346 and eventually gets engulfed in 76 00:02:18.346 --> 00:02:19.973 an explosive event. 77 00:02:19.973 --> 00:02:21.349 Could have been a large planet. 78 00:02:21.349 --> 00:02:21.766 Could have been 79 00:02:21.766 --> 00:02:23.852 a small star in that system. 80 00:02:23.852 --> 00:02:25.728 We don't know what the mass of that 81 00:02:25.728 --> 00:02:26.437 intruder 82 00:02:26.437 --> 00:02:27.856 was, that interloper 83 00:02:27.856 --> 00:02:30.066 that caused this explosive event. 84 00:02:30.316 --> 00:02:31.359 But it is very likely 85 00:02:31.359 --> 00:02:32.443 that it was something 86 00:02:32.443 --> 00:02:33.153 in the neighborhood 87 00:02:33.153 --> 00:02:34.362 of that binary system 88 00:02:34.362 --> 00:02:35.363 that just got too close 89 00:02:35.363 --> 00:02:37.532 to one of those stars, got sucked in, 90 00:02:37.532 --> 00:02:39.784 and we saw this explosion as a result.