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Issued by: Inge Heyer, Science Outreach Specialist Images, notes, and contact details appear below. 13 October 2008 James Clerk Maxwell Telescope Begins Legacy Survey of the Submillimetre SkyA new survey of the universe is underway at the James Clerk Maxwell Telescope (JCMT), on the summit of Mauna Kea, Hawaii, which will give astronomers a new perspective on the origins of the planets, stars, galaxies and the Universe itself. A consortium of astronomers from the UK, Canada and Netherlands have started on the first stages of a large survey of the submillimetre sky using unique instrumentation on the JCMT. The JCMT Legacy Survey is made up of seven projects making use of two new major instruments, SCUBA-2 and HARP. SCUBA-2 is a new powerful camera capable of mapping the sky 1000 times more efficiently than its predecessor. This instrument has recently been delivered to the JCMT and is being commissioned, and, when it is ready, promises to revolutionise the field. In the meantime, three projects have started their surveys using HARP in combination with the imaging spectrometer, ACSIS. These are: the Nearby Galaxies Legacy Survey, the Gould Belt Survey and the Spectral Legacy Survey. Led by Prof. Christine Wilson (McMaster University, Canada), Dr Stephen Serjeant (Open University, UK) and Dr Frank Israel (Leiden University, Netherlands), the Nearby Galaxies Legacy Survey aims to produce the first large sample of galaxies close to our own (within 25 Mpc) to be studied in the submillimetre at good spatial resolution. These data will help us to better understand the properties of the interstellar medium in these galaxies, how it is affected by its environment, and how it compares with our Galaxy. Prof. Wilson says: "It has been very exciting over the last year to go from verifying the performance of HARP/ACSIS on the JCMT to completing over 80% of our HARP survey. We have been kept very busy processing the flood of data that is being produced, but the reward has been seeing all these beautiful images of nearby galaxies appearing one by one. It simply would not have been possible to obtain so many large and sensitive images of our galactic neighbours without HARP/ACSIS. We are using these new data from the Nearby Galaxy Legacy Survey to map out how the dense gas, which is the fuel for forming new stars, is distributed in galaxies with different masses and environments. One of our exciting results is to be able to map, for the first time, how efficiently gas is being turned into stars from one region of a galaxy to another." Closer to home, a complete survey of star formation within 500 pc of our Sun is the aim of the Gould Belt Survey (so-called for the belt of star forming clouds encircling our Sun), a project led by Dr Jennifer Hatchell (University of Exeter, UK), Dr James Di Francesco (HIA, Canada), Dr Michiel Hogerheijde (Leiden Observatory, Leiden University, Netherlands) and Prof. Derek Ward-Thompson (Cardiff University, UK). The JCMT and its instruments are well suited for studies of star formation as it is only at these long wavelengths that we are able to probe into the coldest, densest regions of clouds where stars are actively forming. Dr Hatchell says: "The maps coming out of HARP are larger and better quality than anything we had to work with before. Now we can see just how much the gas clouds are being moved about by the newly-forming stars inside them." The sensitive observations that the JCMT can provide will give astronomers a better understanding of the processes required to form stars and a clearer idea of how often and efficiently this happens. Dr Hogerheijde says: "We knew about the outflows that are shooting off from the newly formed stars; we can see them much better now. But they only contain a small fraction of the gas. What is really exciting is that with these rare types of molecules we can now also see the subtle effects that the outflows may have on the motions of the bulk of the gas – and on its ability to form more stars in the future. The sensitivity and size of HARP allow us to produce maps like this, not just for one star-forming cloud, but for many different regions. We have set out on an exciting journey to uncover the different environments in which stars form in our Solar neighborhood." Prof. Ward-Thompson adds: "These HARP images allow us to see a three-dimensional picture of star birth in molecular clouds. It shows just what a violent process star birth is - in fact almost as violent as a star's death." The details of the star formation process are to be provided by the Spectral Legacy Survey, led by Dr Gary Fuller (University of Manchester, UK), Professor René Plume (University of Calgary, Canada) and Dr Floris van der Tak (SRON, Netherlands). This survey team will obtain a chemical inventory of star formation in a sample carefully selected to be diverse in order to better understand the range of chemical and physical ingredients which ultimately form a star. By obtaining such an inventory towards regions which span different evolutionary stages of development, we will have a comprehensive catalogue of different molecules within sources tracing different phases of star formation. Dr John Richer (Cambridge University, UK) says: "We've never made images like these before. With previous instruments, the maps would have taken too long to make - several weeks or so. But in only eight hours of observing, HARP has generated incredible new images which for the first time reveal the fine details of star formation." "We have been preparing for the JCMT Legacy Survey for several years", says Professor Gary Davis, the Director of the JCMT. "This is the culmination of a process in which astronomers in the UK, Canada and the Netherlands came together to define a unified and comprehensive survey of the submillimetre sky. This has never been done before because the revolutionary instruments required to do it have not, until now, been available. The survey programme is of the highest scientific calibre and will have far-reaching effects on all areas of astrophysics. The spectacular results so far are just a tantalising hint of what is yet to come." The JCMT Legacy Survey is also actively being used by the teams of researchers as a fertile training ground for future astronomers. Matthijs van der Wiel, a PhD student at Kapteyn Astronomical Institute, University of Groningen, and the Institute for Space Research, the Netherlands, says "We know that newly born stars directly affect their surroundings. Since HARP has made observing 16 times faster, we can now for the first time construct a comprehensive view of these violent regions." Robert Simpson, a PhD student from Cardiff university, UK, says: "The images produced by HARP have smashed my old notions of the beautiful and serene nebula. As a kid I always thought nebulae were so gentle and elegant, but images such as these reveal the violence and energy flowing inside them. I've seen the equations and I've read the theory, but these images show you the physics behind star formation in a better, more intuitive way. Working on HARP data during my PhD has given me a new insight into star formation and has changed my perspective. What more can you ask for from science?" Dr Antonio Chrysostomou, Associate Director of the James Clerk Maxwell Telescope, says: "Now that the JCMT Legacy Survey is underway, and we have begun commissioning SCUBA-2, these are very exciting times for us here at the JCMT and in the JCMT community. The data we are seeing from the survey teams are extraordinary and at times spectacular!" Images
[LEFT] This image from the JCMT Nearby Galaxies Legacy Survey shows the integrated carbon-monoxide (12CO) J=3-2 intensity for NGC 3627 (M66) as contours overlaid on an optical image from the Digitized Sky Survey. NGC 3627 is an asymmetric barred spiral galaxy that is well known for its high star formation activity and prominent spiral arms. It is a member of the Leo Triplet of galaxies at a distance of 29 million light years which is well known for its unusual kinematics that are influenced by both its bar and external interactions. Our map shows strong CO 3-2 emission in the central bar and along the spiral arms of the galaxy, with particularly strong emission in the centre and at the ends of the bar. The lopsided structure is similar to past studies at other CO transitions. [RIGHT] This image shows the doppler-shifted velocity field for NGC 3627 (M66) measured using the 12CO J=3-2 emission line.
[LEFT] This image from the JCMT Nearby Galaxies Legacy Survey shows the integrated carbon-monoxide (12CO) J=3-2 intensity for M100 (NGC 4321) as contours overlaid on an optical image from the Digitized Sky Survey. M100 is a nearly face-on grand design spiral galaxy and a member of the Virgo cluster, which lies at a distance of 54 million light years and is the nearest rich cluster of galaxies. Our map shows strong CO 3-2 emission in the centre bulge, with weaker emission in the spiral arms that roughly trace apparent star formation sites. [RIGHT] This image from the JCMT Nearby Galaxies Legacy Survey shows the doppler-shifted velocity field for M100 (NGC 4321) measured using the 12CO J=3-2 emission line. The image shows a very typical velocity field for spiral galaxies of this type, with a steep gradient in the centre of the galaxy and smooth rotation in the outer parts.
[LEFT] Emission of the carbon-monoxide molecule (12CO) from the centre of the Serpens star forming cloud, imaged with HARP during the Gould Belt Survey. The relative motion of the gas is colour coded, with blue showing gas moving at 10 km/s toward us, green showing nearly stationary gas, and red showing gas moving away from us at 10 km/s. These data dramatically show a burst of supersonic jets of gas from this cluster of new-born stars. These jets may be ripping apart part the very cloud from which the stars have formed. The HARP data show how dynamic star birth really is. In this panel (as well as all other ones) the depicted region measures approximately 1.0 by 1.5 light years. See inset figure for orientation of the field. [CENTRE LEFT] Emission from 13CO, the carbon-monoxide molecule substituted with the heavy isotope 13C, with red showing gas moving at 4 km/s away from us, and blue showing gas moving at 4 km/s towards us. [CENTRE RIGHT] Emission from C18O, the carbon-monoxide molecule substituted with the heavy isotope 18O, with red showing gas moving at a few tenths of a km/s away from us, and blue showing gas moving at a few tenths of a km/s towards us. Compare these small velocity shifts with the 10 km/s shifts measured in 12CO. Only 1 in 500 carbon-monoxide molecules carries the 18O atom, allowing us to view much deeper into the cloud and uncover the overall rotation of the cloud (roughly east-west) as well as the subtle effect that the jets seen in regular carbon-monoxide (12CO) may have on the structure and turbulence of the cloud material. [RIGHT] Crosses mark the location of the known newly formed stars, superposed on the map of the carbon-monoxide emission. The compass shows the orientation of the imaged field.
The three panels from the Spectral Legacy Survey show the colour scale and contours of the emission from three different molecules (sulphur monoxide, formaldehyde and a hydrocarbon chain (C2H)) towards the Orion Bar, a region which is being illuminated by a strong ultraviolet radiation field produced by nearby young stars. The asterisks are reference points that mark the same sky position in each image. Moving from the left panel to the right panel, the emission from the different molecules moves towards the upper right of the region, showing that these molecules are clearly present in different layers within the gas. This means that we can choose particular molecules to learn how the physical conditions in the gas (such as density, temperature, and chemical composition) change from one region of the cloud to the next. It is precisely this kind of information that is needed to study the earliest phases of star birth and thus, to help us understand the complex process of star formation.
The James Clerk Maxwell Telescope on Mauna Kea, Hawaii.
ACSIS being tested in the lab in Canada.
HARP on the James Clerk Maxwell Telescope on Mauna Kea, Hawaii.
Notes for EditorsLight YearOne light year is about 10 million million kilometres or 6 million million miles. ParsecOne parsec equals 3.26 light years or 32.6 million million kilometres or 19.56 million million miles. Sub-millimetre LightSub-millimetre wavelengths are much smaller wavelengths than emitted by a typical radio station, but longer wavelengths than light waves or infrared wavelengths. They are typically measured in microns, also called micrometres. One micron is one millionth of a metre, one 10000th of a centimetre, or one 25000th of an inch. JCMTThe James Clerk Maxwell Telescope (JCMT) is the world's largest single-dish submillimetre-wave telescope. It collects faint submillimetre-wavelength signals with its 15 metre diameter dish. It is situated near the summit of Mauna Kea on the Big Island of Hawaii, at an altitude of approximately 4000 metres (14000 feet) above sea level. It is operated by the Joint Astronomy Centre, on behalf of the UK Science and Technology Facilities Council, the Canadian National Research Council, and the Netherlands Organisation for Scientific Research. More about the James Clerk Maxwell Telescope: http://outreach.jach.hawaii.edu/articles/aboutjcmt/ HARPHARP (Heterodyne Array Receiver Programme) is an array of 16 spectral receivers, arranged in a 4x4 grid and using superconducting junctions as the detector elements. ACSIS (AutoCorrelation Spectrometer and Imaging System) is a system of high-speed digital electronics and computers for analysing the signals produced by HARP and other instruments. It contains more than 1000 customised chips and 30 microprocessors for handling the high data rate and producing results in a form that astronomers can use. ACSIS produces data at a rate 1000 times faster than the old JCMT system. Together these instruments have turned the JCMT into a sub-millimetre-wave 3-D camera rather than just a single-point telescope. HARP is a collaboration between the Mullard Radio Astronomy Observatory (MRAO) in Cambridge, UK, the Herzberg Institute of Astrophysics at the Dominion Astrophysical Observatory in Canada (NRC-HIA), the Joint Astronomy Centre in Hilo, Hawaii (operators of the JCMT), and the United Kingdom Astronomy Technology Centre (part of the Science and Technology Facilities Council) in Edinburgh. ACSIS is a collaboration between the Herzberg Institute of Astrophysics at the Dominion Radio Astrophyical Observatory in Canada (NRC-HIA), the Joint Astronomy Centre and the United Kingdom Astronomy Technology Centre. SIS junctions designed by MRAO were fabricated under contract by The TU Delft Institute of Microelectronics and Silicon Technology (DIMES). Science and Technology Facilities CouncilThe Science and Technology Facilities Council is an independent, non-departmental public body of the Office of Science and Innovation which itself is part of the Department of Innovation, Universities and Skills. It was formed as a new Research Council on 1 April 2007 through a merger of the Council for the Central Laboratory of the Research Councils (CCLRC) and the Particle Physics and Astronomy Research Council (PPARC) and the transfer of responsibility for nuclear physics from the Engineering and Physical Sciences Research Council (EPSRC). We are one of seven national research councils in the UK. The Science and Technology Facilities Council is government funded and provides research grants and studentships to scientists in British universities, gives researchers access to world-class facilities and funds the UK membership of international bodies such as the European Organisation for Nuclear Research, CERN, the European Space Agency and the European Southern Observatory. It also contributes money for the UK telescopes overseas on La Palma, Hawaii, Australia and in Chile, the UK Astronomy Technology Centre at the Royal Observatory, Edinburgh and the MERLIN/VLBI National Facility. National Research Council CanadaThe National Research Council (NRC) is the Government of Canada's premier organization for research and development. It reports to Parliament through the Minister of Industry. It is governed by a council of 22 appointees drawn from its client community. NRC is responsible for, among other things, undertaking, assisting or promoting scientific and industrial research in different fields of importance to Canada, operating and administering any astronomical observatories established or maintained by the Government of Canada, administering NRC's research and development activities, including grants and contributions used to support a number of international activities, and providing vital scientific and technological services to the research and industrial communities. This mandate is discharged to a great extent through the operation of the NRC Industrial Research Assistance Program, the NRC Canada Institute for Scientific and Technical Information and the Canadian Technology Network. Netherlands Organisation for Scientific ResearchThe Netherlands Organisation for Scientific Research (NWO) funds thousands of top researchers at universities and institutes and steers the course of Dutch science by means of subsidies and research programmes. NWO is responsible for enhancing the quality and innovative nature of scientific research as equally initiating and stimulating new developments in scientific research, mainly fulfils its task by allocating resources, facilitates, for the benefit of society, the dissemination of knowledge from the results of research that it has initiated and stimulated, and mainly focuses on university research in performing its task. In fulfilling its responsibilities NWO pays due attention to the aspect of coordination and facilitates this where necessary. NWO wants to ensure that Dutch science continues to be amongst the best in the world and that the currently strong position is further strengthened. 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