1 00:00:01,500 --> 00:00:06,500 Star forming regions are some of the most visually striking parts of the night sky. 2 00:00:07,000 --> 00:00:11,000 Within these regions, perhaps the most spectacular stellar fireworks 3 00:00:11,000 --> 00:00:14,500 are the jets of matter that shoot out from new born stars. 4 00:00:14,700 --> 00:00:18,500 Now scientists have used Hubble to watch these jets move, 5 00:00:18,700 --> 00:00:21,200 giving new insights into how stars form. 6 00:00:37,000 --> 00:00:40,000 Episode 49: Supersonic jets from newborn stars 7 00:00:41,500 --> 00:00:45,500 The NASA/ESA Hubble Space Telescope has made detailed observations 8 00:00:45,700 --> 00:00:49,500 of the energetic jets that are ejected from young stars. 9 00:00:50,000 --> 00:00:53,700 Astronomer Patrick Hartigan and his team have been collecting 10 00:00:53,900 --> 00:00:58,700 high-resolution Hubble images of some of these jets for the past 14 years. 11 00:00:59,000 --> 00:01:02,500 The team have now combined their observations into movies that actually 12 00:01:02,700 --> 00:01:06,000 show how the jets evolve over time. 13 00:01:06,500 --> 00:01:09,000 Unlike most astronomical phenomena, 14 00:01:09,200 --> 00:01:12,500 which look completely static even over hundreds of years, 15 00:01:12,700 --> 00:01:16,000 these jets visibly change over human timescales. 16 00:01:17,000 --> 00:01:20,300 Well my first reaction was ‘wow, this is really neat!’ 17 00:01:20,500 --> 00:01:24,500 And it was just really fun just to see all the dynamics of what’s going on. 18 00:01:25,000 --> 00:01:29,600 Because if you just see a single picture you can kinda make up all sorts of stories 19 00:01:29,800 --> 00:01:33,500 but all of a sudden when you see a movie stitched together 20 00:01:33,800 --> 00:01:38,000 it completely changes everything. You really see what’s happening. 21 00:01:38,500 --> 00:01:42,500 If you see just a single picture from Hubble you can interpret it in many different ways. 22 00:01:42,500 --> 00:01:46,000 But the fact that Hubble has been around for as long as it has means that 23 00:01:46,300 --> 00:01:49,500 by taking multiple images you can actually stitch them together 24 00:01:49,500 --> 00:01:52,500 and watch how the material moves. 25 00:01:52,500 --> 00:01:55,500 So that really gives you the only way to get true insight into 26 00:01:55,500 --> 00:02:00,000 the physics of the dynamics of what’s going on. 27 00:02:00,300 --> 00:02:03,500 Some of the details in these jets had never been spotted before. 28 00:02:03,700 --> 00:02:07,500 For instance, the knots of gas brightening and dimming over time, 29 00:02:07,700 --> 00:02:10,500 and the collisions of fast and slow-moving material 30 00:02:10,700 --> 00:02:14,000 show that these jets are not ejected in a steady stream. 31 00:02:14,300 --> 00:02:17,500 Rather, they are launched sporadically in clumps. 32 00:02:17,700 --> 00:02:21,000 Astronomers think that the irregular structure of the jet is caused 33 00:02:21,300 --> 00:02:24,000 by material periodically falling onto the star. 34 00:02:26,000 --> 00:02:31,000 We’re trying to study how stars form. And that’s a complex process 35 00:02:31,300 --> 00:02:35,500 because it has a lot of feedback in the sense that 36 00:02:35,700 --> 00:02:39,000 the stars affect the clouds, and the clouds form the stars. 37 00:02:39,300 --> 00:02:45,500 And just by looking at any particular one process, you don’t get the full picture. 38 00:02:45,800 --> 00:02:49,500 And so the idea is, what we want to try to do is see the main ways in which 39 00:02:49,700 --> 00:02:53,500 the stars can affect the surrounding molecular clouds. 40 00:02:54,000 --> 00:02:57,500 These jets are known to scientists as Herbig-Haro objects, 41 00:02:57,700 --> 00:03:00,500 in honour of George Herbig and Guillermo Haro, 42 00:03:00,700 --> 00:03:04,000 two astronomers who studied these outflows in the 1950s. 43 00:03:04,300 --> 00:03:08,500 However it is only now that their complex nature is coming to light. 44 00:03:08,700 --> 00:03:11,500 As well as detailed Hubble observations, 45 00:03:11,700 --> 00:03:15,500 members of the team have carried out lab experiments and computer simulations 46 00:03:15,700 --> 00:03:18,500 in scientific facilities around the world 47 00:03:18,700 --> 00:03:21,300 including New York’s Omega Laser Facility 48 00:03:21,500 --> 00:03:24,000 and the UK Atomic Weapons Establishment. 49 00:03:24,300 --> 00:03:28,300 By combining observations, experiments and simulations, 50 00:03:28,500 --> 00:03:31,000 scientists can attack the problem how stellar jets behave 51 00:03:31,300 --> 00:03:34,000 from three different perspectives. 52 00:03:34,500 --> 00:03:39,000 The entire process is really very complex and it’s very important to understand, 53 00:03:39,300 --> 00:03:43,000 because that’s how our Sun formed and that’s how planetary systems form, 54 00:03:43,300 --> 00:03:46,500 and that’s basically how we got here. 55 00:03:48,000 --> 00:03:52,000 The next Hubblecast will, in fact, be our 50th episode. 56 00:03:52,300 --> 00:03:55,500 To celebrate this occasion, we are asking you to tell us 57 00:03:55,700 --> 00:03:58,700 what you want me to talk about in that episode. 58 00:03:59,000 --> 00:04:02,000 So, send us your astronomy related questions 59 00:04:02,200 --> 00:04:06,000 either by posting them to our Facebook page at facebook.com/hubbleESA 60 00:04:06,300 --> 00:04:11,000 or by emailing me at drj@spacetelescope.org. 61 00:04:11,000 --> 00:04:17,500 Full details are, of course, available on our webpage at www.spacetelescope.org. 62 00:04:21,500 --> 00:04:24,500 Transcribed by ESA/Hubble.