Institute of Astronomy PUBLIC OPEN EVENING outreach — 22 November 2017 — A

Astronomers see clash of ‘titan’ TONIGHT’S SPEAKER galaxies – 13 billion years ago The talk schedule for can be viewed this term at:

Ricardo Chavez The Dark Universe

Our weekly welcome ELCOME to our weekly Wpublic open evenings for the 2017/18 season. Each night there will be a half-hour talk which begins promptly at 7.15pm: tonight A pair of exceptionally rare hyper-luminous galaxies. The background image is from ESA’s Ricardo Chavez will be telling us Herschel Space Observatory, the middle is from ESO’s Atacama Pathfinder EXperiment (APEX) about The Dark Universe. telescope and on the right is the ALMA image, clearly showing the two starbursting galaxies. The talk is followed by an

Credit: NRAO/AUI/NSF,B. Saxton; ESA Herschel; ESO APEX; ALMA(ESO/NAOJ/NRAO); D. Riechers opportunity to observe if (and www.ast.cam.ac.uk/public/public_observing/current only if…) the weather is clear. NEW observations with the Ataca- and greater sensitivity of ALMA that The Cambridge Astronomical ma Large Millimeter/submillimeter astronomers could measure the Association will provide a floorshow Array (ALMA) have discovered a close precise distance to the object and see outdoors on the Observatory lawns, encounter between two astounding- that it was in fact two distinct galaxies. relaying live images from modern ly bright and spectacularly massive The pairing of two otherwise phenom- telescopes with a commentary. The galaxies in the early universe. These enally rare galaxies suggests that they IoA’s historical Northumberland so-called hyper-luminous starburst existed in a particularly dense region and Thorrowgood telescopes galaxies are exceedingly rare at this ep- of the universe during that period in will be open for unaided eye och of cosmic history – near the time its history. when galaxies first formed – and may The new observations also indi- observations, along with the 16-inch represent one of the most-extreme cate that the ADFS-27 system has telescope. If we’re unlucky and it’s examples of violent star formation approximately 50 times the amount cloudy, we’ll offer you a cup of tea ever observed. of star-forming gas as the Milky Way. as compensation after the talk, The two interacting galaxies, collec- Much of this gas will be rapidly con- with perhaps some more astro- tively known as ADFS-27, are located verted into new stars, at rates about information in the lecture theatre for approximately 12.7 billion light-years one thousand times faster than in our those who want to stay on. from ; so we are viewing the sys- home galaxy. tem as it appeared when the universe The two galaxies are about 30,000 If you have any questions, suggestions was only about one billion years old. light-years apart, and moving at The galaxies were first detected roughly several hundred kilometres or comments about the IoA Open with the Herschel Space Observatory, per second relative to each other. Evenings please contact Carolin Crawford but appeared just as a single dot that Over the next few hundred million at [email protected] or Matt Bothwell the telescope could not resolve. Fol- years they will eventually slow and fall at [email protected]. We tweet low-up observations confirmed that toward the other, merging into one current astro-news and events as ADFS-27 was in fact both extremely massive elliptical galaxy after several @cambridge_astro bright and extremely distant. But it more close encounters. was only with the higher resolution www.ast.cam.ac.uk/public 2 — IOA PUBLIC OPEN EVENING — 22 November 2017

Closest temperate world orbiting Hitomi reveals quiet star discovered X-ray landscape temperatures between -60 and +20°C thanks to the cool and faint nature of the small star, which has just over half the surface temperature of the Sun. Uncertainty remains as to whether the planet lies within the star’s habitable zone, where liquid water may exist on a planet’s surface. Credit: RobertCredit: Lupton/SDSS/NASA Red dwarfs are some of the coolest, faintest – and most common – stars The Perseus galaxy cluster overlaid with a in the universe. They are thus prime part of the Hitomi spectrum. targets in the search for . BEFORE its brief mission ended unex- However, many such red dwarf stars, pectedly in March 2016, Japan’s Hitomi including (the clos- Artist’s impression of b, with its red X-ray observatory captured exceptional est star to the solar system), produce dwarf parent star in the background. information about the motions of hot violent flares that occasionally bathe Credit: ESO/M. Kornmesser gas in the Perseus galaxy cluster. their orbiting planets in deadly ultra- The Perseus cluster, located 240 A temperate Earth-sized planet has violet and X-ray radiation. However, it million light-years away, is the brightest been discovered only 11 light-years seems that Ross 128 is a much quieter galaxy cluster in X-rays and among the from the solar system orbiting around star, and so its planets may be the most massive near Earth. Thousands of a quiet red dwarf star. closest known comfortable abode for galaxies bound together by gravity orbit Scientists working with the High Ac- possible life. within a thin hot gas. This gas is at a curacy Radial velocity Planet Searcher Although it is currently 11 light- temperature of 50 million °C and is the (HARPS) at the years from Earth, Ross 128 is moving source of the cluster’s X-ray emission. in Chile have found that the red dwarf towards us and is expected to become The researchers obtained a spec- star Ross 128 is orbited by an Earth- our nearest stellar neighbour in just trum of unprecedented detail, which sized (called Ross 128 b) 79,000 years – a blink of the eye in cos- revealed a landscape of X-ray peaks every 9.9 days. Even though it is 20 mic terms. Ross 128 b will by then take emitted from various chemical ele- times closer to its host than the Earth the crown from Proxima b and become ments with 30 times better resolution is to the Sun, it is expected to have the closest exoplanet to Earth! than any previous data. The propor- tions of elements found in the cluster are nearly identical to those in the Sun Britain’s new Unst is the northernmost Unst of the inhabited British – an unexpected result, given that the space port? Perseus cluster is an environment with Isles and a potential site Shetland Islands a very different history from our Sun’s. Unst, the most northern island in the for a spaceport. Shetlands with a population of only 600, has been identified by the UK Joke of the Week Space Agency as the best site in the UK A spiral galaxy walked into a bar for a drink. for a spaceport to launch satellites into The bartender threw him out and said orbit around Earth. Inverness Aberdeen “You’re barred!” The proposals are at an early stage, but the Shetland Space Centre Ltd has already been set up on the island, a Edinburgh breathtaking fragment nearer Norway Glasgow than it is to Edinburgh. A report suggested that rockets launched from Saxa Vord on Unst Credit: [email protected] could carry the greatest payloads into sites which would have to perform commercially valuable orbits with the avoidance manoeuvres, limiting the lowest risk to inhabitants should the weight of the payload they could carry. spacecraft launch fail. Unst is so far north that rockets could lift off straight into orbit without passing over pop- The potential key site for satellite launches ulated areas, unlike those from other on Unst. Credit: Getty Images