Institute of Astronomy PUBLIC OPEN EVENING outreach — 25 January 2017 — A Conditions right for complex life TONIGHT’S SPEAKER in Earth’s distant past? The talk schedule for this term can be viewed at: this term can be viewed talk schedule for The Christina Hedges Alien Megastructures or a Cloud of Comets? Our weekly welcome ELCOME to our season of Wweekly public open evenings which will run through to the end of March. Each night starts promptly A 1.9-billion-year-old stromatolite — a mound made by microbes that lived in shallow water with a short talk at 7.15pm in the — called the Gunflint Formation in northern Minnesota. Credit: Eva Stüeken lecture theatre: tonight Christina Hedges will be giving her talk Alien Megastructures or a Cloud of CONDITIONS suitable to support time in order to give the organisms Comets? www.ast.cam.ac.uk/public/public_observing/current complex life may have developed in a chance to evolve into a substantial Earth’s oceans — and then faded — part of the ecosystem. The talk is followed by an oppor- more than a billion years before life Previously, it was thought that ox- tunity to observe if (and only if…) truly took hold. ygen on Earth had a history of “none, the weather is clear. The Cambridge Fossils on Earth provide evidence of then some, then a lot”. However, from Astronomical Association will pro- complex cells dating as far back as 1¾ the new studies it now seems there vide a floorshow outdoors on the billion years. But maybe life originat- was a period of a quarter of a billion Observatory lawns, relaying live im- ed earlier, as the oldest fossil found years or so when oxygen levels were ages from modern telescopes with is not necessarily the first that ever quite high before sinking back down a commentary. The IoA’s historical lived – because the chances of getting again. However, it still remains unclear Northumberland and Thorrowgood preserved as a fossil are pretty low. what made the oxygen levels rise telescopes will be open for unaided A new study uses the element sele- dramatically and then crash again in eye observations, along with the nium in sedimentary rocks on Earth the first place. 16-inch telescope. If we’re unlucky as a tool to measure the presence of The new method using selenium and it’s cloudy, we’ll offer you a cup oxygen in Earth’s atmosphere between can also be helpful in the search for of tea as compensation after the talk, 2 and 2.4 billion years ago. The abun- oxygen — and so perhaps complex life with some more astro-information dance of selenium increases in the — beyond Earth. Future generations in the lecture theatre for those who rocks when a lot of oxygen is present. of space-based telescopes, will give want to stay on. The research shows that there was astronomers information about the enough oxygen in the environment to atmospheric composition of distant have allowed complex cells to have planets. Some of these could be ap- evolved (and to have become ecolog- proximately Earth-sized and potential- If you have any questions, suggestions or ically important) at times predating ly have appreciable atmospheric oxy- comments about the IoA Open Evenings the fossil evidence. This doesn’t mean gen. By measuring the oxygen levels in – please contact Carolin Crawford at that organisms actually evolved, only a planet’s historical past, we might tell [email protected]. We tweet current astro- that they potentially could have. The how long conditions suitable for life news and events as IOACOA. oxygen needs to have been sustained have persisted, and whether it might at the right level over a long period of have evolved into intelligent beings. www.ast.cam.ac.uk/public 2 — IOA PUBLIC OPEN EVENING — 25 January 2017 Presumed young star turns out to be a galactic senior citizen IT WAS considered a teenager among its spectrum, and the chemical the stars. But now astronomers have composition can then be used to realised that this celestial object was determine the age. Old stars that had formed when our galaxy was born. been formed during an early stage Why did researchers get it wrong for of the universe collapsed from more many decades? primordial gas which does not contain 49 Librae was assumed to be 49 Librae is a relatively bright star in any heavy elements. These elements only 2.3 billion years old, but is the southern sky, and has been recently were generated later, following the actually about 5 times older. discovered to be twelve billion years old nuclear fusion of many generations (which is approximately the time that of stars. Young stars such as our sun our galaxy was born) rather than just possess heavy elements, because they ferred to it from an invisible compan- 2.3 billion years old (about half the age have emerged from the remnants of ion during the end stages of its life. The of our sun). But how do you tell how past generations of stars. two stars have been in orbit around old a star is anyway? As the spectrum of the mysterious each other all this time, but as the In order to determine the ages of star 49 Librae reveals the presence of companion star puffed up to become a stars, astronomers use stellar spectra: heavy elements, researchers used to red giant, its own gravity was no longer they break the light emitted by the star think for many decades that it is a rel- sufficient to keep the star together. As into its individual components and atively young celestial body. However, the companion’s outer layers dispersed decode the wavelength at which the the recent research has discovered that into space, 49 Librae’s gravity attracted star emits the most light. The chemical these heavy elements did not originate and absorbed the expelled matter (and composition of a star determines from 49 Librae, but had been trans- gained its heavy elements). A journey of a million miles begins with a single step In the top panel is the eROSITA X-ray telescope after final integration. In the middle panel The project to build eROSITA eROSITA is being loaded into the cargo plane started in 2007. More than a hundred at Munich airport (bottom) on its way to people have been working on its Moscow, the first 2300 kilometres of its various components, many of which journey into space. Credits: MPE had to be developed from scratch. In Moscow it will be further tested and On 20 January 2017, the completed integrated with the Spectrum-Roent- eROSITA X-ray telescope boarded a gen-Gamma (SRG) spacecraft, which cargo plane and was transported from will be launched on a Proton rocket Munich, where it had been built, to from the Russian launch site Baikonur Moscow for further testing. It will be in Kazakhstan. Once in space, eROSITA launched in spring 2018. will then travel a distance of about 1.5 The eROSITA X-ray space telescope million kilometres away from Earth will – amongst other things - be used to from where it will survey the entire sky observe millions of active black holes in X-rays eight times over the course of at the centres of galaxies as well as to four years. study clusters of galaxies and how they are distributed in the sky. The survey will provide new insights into a wide range of high-energy astrophysical Scott’s joke of the week phenomena and give new clues about the mysterious “Dark Energy”, the force Living on Earth might be expensive but at behind the accelerated expansion of least you get a free trip around the Sun every the Universe. year..