1 00:00:00,000 --> 00:00:07,000 The NASA/ESA Hubble Space Telescope has captured a new image of the galaxy NGC 1132 2 00:00:07,000 --> 00:00:13,000 which is most likely to be a “cosmic fossil” – the aftermath of an enormous multi-galactic pile-up, 3 00:00:13,000 --> 00:00:22,000 where the carnage of collision after collision has built up a brilliant but fuzzy giant elliptical galaxy far outshining typical galaxies. 4 00:00:40,000 --> 00:00:42,000 This is the Hubblecast! 5 00:00:42,000 --> 00:00:46,000 News and Images from the NASA/ESA Hubble Space Telescope. 6 00:00:46,000 --> 00:00:52,000 Travelling through time and space with our host Doctor J a.k.a. Dr Joe Liske. 7 00:00:53,000 --> 00:00:55,000 Welcome to the Hubblecast. 8 00:00:55,000 --> 00:01:00,000 In this episode we will take a close look on the latest image from Hubble Space Telescope. 9 00:01:00,000 --> 00:01:04,000 It shows the giant elliptical galaxy NGC 1132. 10 00:01:04,000 --> 00:01:10,000 Now you may ask: “what is so special about this fuzzy, seemingly bland object?” 11 00:01:10,000 --> 00:01:16,000 Well, the interesting thing about it is not so much what it looks like today, but rather what happened in its past. 12 00:01:16,000 --> 00:01:22,000 Let’s try to trace its history by taking a very close look at its present day features. 13 00:01:24,000 --> 00:01:33,000 NGC 1132 is located about 320 million light-years away from Earth, in the constellation of Eridanus, the River. 14 00:01:35,000 --> 00:01:40,000 At first glance NGC 1132 looks like any other ordinary elliptical galaxy – 15 00:01:40,000 --> 00:01:45,000 it is smooth, featureless and contains hundreds of millions of stars 16 00:01:45,000 --> 00:01:50,000 whose yellowish colour is a telltale sign of their great age. 17 00:01:50,000 --> 00:01:55,000 But closer up, we see that NGC 1132 is rather special. 18 00:01:55,000 --> 00:01:57,000 It is humongous! 19 00:01:57,000 --> 00:02:00,000 Many times larger than the average elliptical galaxy. 20 00:02:00,000 --> 00:02:04,000 It belongs to a category of galaxies called giant ellipticals. 21 00:02:04,000 --> 00:02:12,000 Seen in visible light, NGC 1132 appears as a single, almost isolated, giant galaxy. 22 00:02:12,000 --> 00:02:15,000 But this is only the tip of the iceberg. 23 00:02:15,000 --> 00:02:20,000 Scientists have found that NGC 1132 resides in an enormous halo of dark matter, 24 00:02:20,000 --> 00:02:26,000 comparable to the amount usually found in an entire group of tens to hundreds of galaxies. 25 00:02:26,000 --> 00:02:35,000 It also has a strong X-ray glow from an abundance of hot gas – an amount normally only found in galaxy groups. 26 00:02:35,000 --> 00:02:44,000 In fact its X-ray glow extends over a region of space ten times larger than the 120,000 light-years radius seen in visible light. 27 00:02:44,000 --> 00:02:48,000 This is a glow equal in size to that of an entire group of galaxies. 28 00:02:50,000 --> 00:02:59,000 So there’s enough dark matter and hot gas here for an entire group of galaxies and yet we see only a single, although gargantuan galaxy. 29 00:02:59,000 --> 00:03:01,000 Well, actually, not quite. 30 00:03:01,000 --> 00:03:09,000 If we look closely at the image, we can see that NGC 1132 is actually associated with a whole bunch of small dwarf galaxies – 31 00:03:09,000 --> 00:03:15,000 which look a little bit like huge wads of cotton - but there are definitely no medium-sized galaxies. 32 00:03:15,000 --> 00:03:17,000 So what’s going on? 33 00:03:17,000 --> 00:03:23,000 The most likely explanation is that NGC 1132 is the result of galactic cannibalism. 34 00:03:23,000 --> 00:03:26,000 It is probably a so-called “fossil group”. 35 00:03:26,000 --> 00:03:31,000 In other words what we are looking at here, are the remains of an entire group of galaxies 36 00:03:31,000 --> 00:03:36,000 that have all merged together into a single galaxy at some point in its past. 37 00:03:36,000 --> 00:03:45,000 If we examine the image closely we can also see that NGC 1132 is surrounded by thousands of ancient globular clusters, 38 00:03:45,000 --> 00:03:49,000 swarming around the galaxy like bees around the hive. 39 00:03:49,000 --> 00:03:57,000 These globular clusters are most likely survivors of the disruption of their parent galaxies that have been swallowed by NGC 1132. 40 00:03:57,000 --> 00:04:02,000 And because of that, they can tell us a lot about the merging history of the whole group. 41 00:04:04,000 --> 00:04:08,000 There is a stunning tapestry of numerous galaxies that are much further away 42 00:04:08,000 --> 00:04:12,000 and have nothing to do with the fossil group in the foreground. 43 00:04:15,000 --> 00:04:20,000 The formation of “fossil groups” remains a puzzle that astronomers are still trying to solve. 44 00:04:20,000 --> 00:04:25,000 The most likely explanation is that it they are the end-product of a cosmic feeding frenzy 45 00:04:25,000 --> 00:04:29,000 in which a large galaxy devours all its neighbours. 46 00:04:29,000 --> 00:04:36,000 An alternative but less favoured view is that they may be very rare objects that formed in a region of space or period of time 47 00:04:36,000 --> 00:04:42,000 where the growth of medium-sized galaxies was somehow suppressed, and only one large galaxy formed. 48 00:04:46,000 --> 00:04:52,000 Many galaxies, including our own Milky Way, reside in groups that are gravitationally bound together. 49 00:04:52,000 --> 00:04:59,000 There is plenty of evidence that the Milky Way is also a cannibal and has snacked on numerous smaller galaxies thoughout its lifetime, 50 00:04:59,000 --> 00:05:02,000 inheriting their stars in the process. 51 00:05:02,000 --> 00:05:08,000 What will happen to the Milky Way and its neighbours over the next few billions of years? 52 00:05:08,000 --> 00:05:12,000 Well, this is precisely one of the questions that astronomers are trying to answer 53 00:05:12,000 --> 00:05:17,000 when they study the structure and the evolution of other galaxies such as NGC 1132. 54 00:05:17,000 --> 00:05:21,000 By analysing their properties, it is possible to trace back the history 55 00:05:21,000 --> 00:05:26,000 and to better understand what will happen in our own neighbourhood in the future. 56 00:05:26,000 --> 00:05:29,000 This is Dr J signing off for the Hubblecast. 57 00:05:29,000 --> 00:05:35,000 Once again nature has surprised us beyond our wildest imagination … 58 00:05:36,000 --> 00:05:39,000 Hubblecast is produced by ESA/Hubble at ESO in Germany. 59 00:05:40,000 --> 00:05:45,000 The Hubble mission is a project of international cooperation between NASA and the European Space Agency.