Institute of Astronomy PUBLIC OPEN EVENING outreach — 4 March 2015 — A

Barely time to gather dust: Early TONIGHT’S SPEAKER too metal-rich for its age A DUSTY young galaxy has been the end of their lives. discovered in the very early Universe, Dust should thus take a while challenging our understanding of how to form, and the early are quickly heavy elements are formed and expected to be composed mostly of dispersed into gas clouds in galaxies. gas instead, not having had sufficient “Dust” is the term used by astrono- time to create large quantities of heavy Andrew Connolly mers to describe tiny particles of rocky elements over a few generations of What is the next window matter (silicates and carbonates, massive star formation. onto our Universe? literally fine grains of soot and sand) It is thus surprising to have found that are crucial to the formation of such a dusty galaxy dating from when planetary systems. the Universe was only 700 million Our weekly welcome Astrophysical dust is made of years old (5% of its present age). ONIGHT’S half-hour talk begins relatively heavy elements such as car- Although this galaxy is not very promptly at 7.15pm, when bon, oxygen, iron and silicon—these large, it is already as rich with inter- T Andrew Connolly will tell us how are synthesised from the primordial stellar dust as the . It must the Large Synoptic Survey Telescope and helium only within the have either been consistently form- cores of massive stars, and are liber- ing stars for over 100 million years, or may be used to map the Universe in ated into the surrounding interstellar undergone an extreme but temporary unprecedented depth and detail. medium when these stars explode at “starburst” of stellar formation activity. His talk will be followed by an opportunity to observe if (and only if…) the weather is clear. The IoA’s historical Northumber- land and Thorrowgood telescopes will be open for unaided-eye observations, and we will be staffing some smaller telescopes around the observatory lawns. The Cambridge Astronomical Association will also provide an out- doors floorshow relaying live images from three modern telescopes, with commentary. If we’re unlucky and it’s cloudy, then we’ll offer you a cup of tea as compensation, and the CAA will offer some more astro-information afterwards in the lecture theatre for those who want to stay on. A image of the galaxy cluster (above), with a close-up of the square region (left). The We tweet current astro-news and events reddish object in this region is the young as IoACOA. Please e-mail any questions, galaxy A1689-zD1, which ALMA and VLT comments or suggestions about the IoA observations have revealed to be dust-rich. Public Open Evenings to Carolin Crawford Images: NASA/ESA/ESO/L. Bradley/R. at [email protected] Bouwens/H. Ford/G. Illingworth/J. Richard www.ast.cam.ac.uk/public 2 — IOA PUBLIC OPEN EVENING — 4 March 2015

ASTRONOMERS have discovered a surpris- This theoretical model predicts a fairly ingly massive black hole that was already gradual increase in black hole size with the actively accreting matter early on in the age of the Universe. Universe. Spotted: It is thus weird to have discovered a Supermassive black holes reside at black hole with the mass of 12 billion the centres of all massive galaxies, and A huge but Suns so very early in cosmological his- each can shine as a very luminous “qua- tory, when the Universe was only 900 sar” in periods when it is accreting mat- over-aged million years old. ter from its immediate surroundings. It is hard to understand how such a There is an inherent chicken-and-egg black hole massive object can have formed so early problem with such black holes: which on—this period follows only just after the came first, the black hole or its host galaxy? formation of the very first generations of stars The current idea is that the two grow in and galaxies. tandem—the black hole needs the surrounding galaxy The black hole at the centre of the quasar needs for fuel, but it can’t accrete too much or else the energy it to have gained an enormous mass in a very short period of releases will shut down stellar (and thus galaxy) formation. time—so maybe the black hole did come first?

X-RAY and radio observations have revealed an unusual type of black hole in an arm of a nearby spiral galaxy. …and a Black holes are observed in two flavours—smaller medium stellar-sized black holes that represent the remnants of massive stars (30–50 Solar masses), and the supermas- rare one sive versions (millions to billions of Solar masses) living at the hearts of large galaxies. The new black hole (circled in the image below) lies in the galaxy NGC 2276, and appears to have a mass about Dawn probe due in 50,000 times that of the Sun, i.e. falling in between the two well-established at Ceres this week groups. This makes it one of the first “intermediate-mass” black holes to be dis- covered—they have long been predicted, but have proven very difficult to find. THE DAWN spacecraft is set to The question now is whether the black arrive into orbit around the dwarf hole grew in situ in the galaxy’s spiral arm, planet Ceres this Friday. or began as a half-formed supermassive At 950 km across, Ceres is the object in the core of a dwarf galaxy that was largest object in the asteroid belt digested by the larger galaxy. between Mars and Jupiter. It’s mas- There is also a jet of radio plasma extend- sive enough to be spherical, while ing 2,000 light-years from the black hole; an its crust is ice-rich and mixed with a absence of young stars along the line of the thin layer of dusty particles. jet suggests the black hole has suppressed Dawn’s latest images of Ceres star formation in its local environment. (above) have revealed a battered Image: NASA/CXC/SAO/INAF/STScI surface with plenty of craters, and curious white spots that could reveal the presence of water ice. When Dawn arrives at Ceres, it Other things that caught our eye will have its cameras pointing the wrong way due to a thruster failure, TAKE A PART-TIME ASTRO COURSE Please call 01223 746236 or visit and will take till the end of April to Cambridge’s Institute of Continuing www.ice.cam.ac.uk/astronomy- swing round and look at the surface. Education is offering a one-year, part- certificate for further information. We expect to learn more from time course in astronomy. UPCOMING POP ASTRONOMY TALKS Dawn over the next 16 months about The certificate provides an intro- the origin and evolution of Ceres. duction to the field of astronomy, and The Society of Popular Astronomy are Image: NASA/JPL-Caltech/UCLA/ the opportunity to learn about planets, holding their annual convention at the MPS/DLR/IDA stars and galaxies, from the Solar Sys- IoA on 28th March, 10am–5.30pm. tem to the Milky Way and beyond. They have a great line-up of talks The course is taught over three on topics such as the Rosetta mission, Scott’s joke of the week termly units, each with its own topic; ExoMars and the Solar Orbiter. the sessions are on Monday evenings Entry is free, but there are no tickets – When is the Moon the heaviest? at Madingley Hall in Madingley. remaining for the Rosetta lecture. – When it’s full!