1 00:00:03,000 --> 00:00:07,000 Today, at an international exoplanet conference 2 00:00:07,000 --> 00:00:11,000 the team who built the High Accuracy Radial Velocity Planet Searcher, 3 00:00:11,000 --> 00:00:16,000 better known as HARPS, the spectrograph for ESO’s 3.6-metre telescope, 4 00:00:16,000 --> 00:00:20,000 reports on the incredible discovery of more than 30 new exoplanets, 5 00:00:20,000 --> 00:00:25,000 cementing HARPS’s position as the world’s foremost exoplanet hunter. 6 00:00:29,000 --> 00:00:31,000 This is the ESOcast! 7 00:00:31,000 --> 00:00:36,000 Cutting-edge science and life behind the scenes of ESO, the European Southern Observatory. 8 00:00:36,000 --> 00:00:42,000 Exploring the ultimate frontier with our host Dr J, a.k.a. Dr Joe Liske. 9 00:00:46,000 --> 00:00:48,000 Hello and welcome to the ESOcast. 10 00:00:48,000 --> 00:00:54,000 In this episode, we have another major exoplanet discovery coming to you from ESO’s La Silla Observatory. 11 00:00:54,000 --> 00:00:59,000 And we're not just talking about just one exoplanet, we're talking about no less than 30! 12 00:00:59,000 --> 00:01:01,000 It's exoplanets galore! 13 00:01:02,000 --> 00:01:06,000 Including these new results, data from HARPS has led to the discovery 14 00:01:06,000 --> 00:01:11,000 of more than 75 exoplanets in 30 different planetary systems. 15 00:01:11,000 --> 00:01:16,000 In particular, thanks to its amazing precision, the search for small planets, 16 00:01:16,000 --> 00:01:22,000 those with a mass of a few times that of the Earth — known as super-Earths and Neptune-like planets — 17 00:01:22,000 --> 00:01:24,000 has been given a dramatic boost. 18 00:01:24,000 --> 00:01:33,000 HARPS has facilitated the discovery of 24 of the 28 planets known with masses below 20 Earth masses. 19 00:01:33,000 --> 00:01:40,000 As with the previously detected super-Earths, most of the new low-mass candidates reside in multi-planet systems, 20 00:01:40,000 --> 00:01:43,000 with up to five planets per system. 21 00:01:45,000 --> 00:01:52,000 In 1999, ESO launched a call for opportunities to build a high resolution, extremely precise spectrograph 22 00:01:52,000 --> 00:01:56,000 for the ESO 3.6-metre telescope at La Silla, Chile. 23 00:01:57,000 --> 00:02:02,000 Michel Mayor, from the Geneva Observatory, led a consortium to build HARPS, 24 00:02:02,000 --> 00:02:08,000 which was installed in 2003 and was soon able to measure the back-and-forward motions of stars 25 00:02:08,000 --> 00:02:17,000 by detecting small changes in a star’s radial velocity as small as 3.5 km/hour, or a steady walking pace. 26 00:02:18,000 --> 00:02:21,000 Such a precision is crucial for the discovery of exoplanets. 27 00:02:21,000 --> 00:02:26,000 The radial velocity method, which detects small changes in the radial velocity of a star 28 00:02:26,000 --> 00:02:31,000 as it wobbles slightly under the gentle gravitational pull from an unseen exoplanet, 29 00:02:31,000 --> 00:02:35,000 has been most prolific method in the search for exoplanets. 30 00:02:36,000 --> 00:02:44,000 In return for building the instrument, the HARPS consortium was awarded 100 observing nights per year over a five-year period. 31 00:02:44,000 --> 00:02:50,000 Now this time was used to carry out one of the most ambitious systematic searches for exoplanets so far implemented worldwide 32 00:02:50,000 --> 00:02:56,000 by measuring the radial velocities of hundreds of stars that might harbour planetary systems. 33 00:02:57,000 --> 00:03:00,000 The programme soon proved very successful. 34 00:03:00,000 --> 00:03:07,000 Using HARPS, Mayor’s team discovered — among others — the first super-Earth around Mu Arae; 35 00:03:07,000 --> 00:03:11,000 the trio of Neptunes around HD 69830; 36 00:03:11,000 --> 00:03:17,000 Gliese 581d, the first extrasolar planet in the habitable zone of a small star; 37 00:03:17,000 --> 00:03:24,000 and the lightest exoplanet ever detected around a normal star, Gliese 581e. 38 00:03:24,000 --> 00:03:31,000 More recently, they found a potentially lava-covered world, with density similar to that of the Earth’s. 39 00:03:32,000 --> 00:03:37,000 These observations have given astronomers great insight into the diversity of planetary systems 40 00:03:37,000 --> 00:03:40,000 and they have helped us to understand how they might form. 41 00:03:41,000 --> 00:03:45,000 The HARPS consortium was very careful in their selection of targets, 42 00:03:45,000 --> 00:03:50,000 with several sub-programmes aimed at looking for planets around solar-like stars, 43 00:03:50,000 --> 00:03:56,000 low-mass dwarf stars, or stars with a lower metal content than the Sun. 44 00:03:57,000 --> 00:04:01,000 Although it was thought that giant planets couldn’t form around low-mass stars, 45 00:04:01,000 --> 00:04:04,000 the HARPS team has found several of them. 46 00:04:04,000 --> 00:04:09,000 The number of exoplanets known around low-mass stars — so-called M dwarfs — 47 00:04:09,000 --> 00:04:14,000 has also dramatically increased, including new super-Earth candidates. 48 00:04:15,000 --> 00:04:19,000 Although the first phase of the observing programme is now officially concluded, 49 00:04:19,000 --> 00:04:21,000 two new programmes have been started. 50 00:04:21,000 --> 00:04:25,000 And the team still expects to make many new discoveries from the first 5 years of data. 51 00:04:25,000 --> 00:04:30,000 There is no doubt that HARPS will continue to lead the field of exoplanet discovery, 52 00:04:30,000 --> 00:04:34,000 and especially pushing towards the detection of Earth-type planets. 53 00:04:34,000 --> 00:04:37,000 This is Dr J signing off for the ESOcast. 54 00:04:37,000 --> 00:04:40,000 Join me again next time for another cosmic adventure. 55 00:04:41,000 --> 00:04:44,000 ESOcast is produced by ESO, the European Southern Observatory. www.eso.org 56 00:04:44,000 --> 00:04:47,000 ESO, the European Southern Observatory, is the pre-eminent intergovernmental science and technology organisation in astronomy 57 00:04:47,000 --> 00:04:50,000 designing, constructing and operating the world's most advanced ground-based telescopes. 58 00:04:52,000 --> 00:04:55,000 Transcription by ESO ; 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