﻿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.