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Issued by: Inge Heyer, Science Outreach Specialist Images, notes, and contact details appear below. 17 May 2007 Slicing the Universe with HARP/ACSIS - A New Look at OrionThe James Clerk Maxwell Telescope (JCMT) on Mauna Kea in Hawaii has a new way to look at the Universe, thanks to two revolutionary instruments called HARP and ACSIS. These instruments operate together, and they recently sliced through the Orion Nebula, recording for the first time the internal movements of its star-forming gases. Orion is one of the most famous and recognisable constellations in the sky. At its heart, it harbours a vast cloud of gas and dust, the Orion Nebula, which is undergoing a burst of star formation. Astronomers refer to this and other similar regions as "stellar nurseries". Within this cloud, gas and dust extend over vast regions and help to "feed" the star formation. Gravity takes the gas and dust in these clouds and compresses it into stars. HARP and ACSIS allow astronomers to see the motion of this gas with a clarity and precision not previously available at these wavelengths. Together they give the JCMT the powerful ability to record information in three dimensions. Unlike the previous generation of receiver systems, HARP/ACSIS can produce camera-like images of the sky across thousands of adjacent wavelengths simultaneously, forming a three-dimensional image set called a "spectral cube". The wavelength dimension permits the telescope to sense molecular tracers as well as to detect the motions of the gas. These slices of wavelength reveal to astronomers the chemical make-up of our Galaxy and others in the Universe. There are many gas molecules that exist in space which emit radiation at wavelengths that HARP/ACSIS can tune to. The JCMT observes in the sub-millimetre range of wavelengths, much smaller wavelengths than a typical radio station, but much longer wavelengths than light waves. The naturally occurring emission from gas and dust in the material between the stars is particularly effective at revealing the processes of material accumulation to form stars. This process is still mysterious in its details, and the HARP/ACSIS receiver system on the JCMT is exquisitely tuned to study the precise constituents and motions of the gas and dust as it collapses to form stars. And that makes this instrument the perfect tool to examine the Orion Nebula. The information that is recorded along the third "wavelength" dimension shows how much the gas molecules, in this case carbon monoxide, are radiating and how fast they are moving. We see gas with large motions both towards us and away from us at velocities approaching and exceeding 200 km/s (that's nearly half a million miles an hour). These velocity slices can be combined into a movie, allowing us to see that the hot nebula at the centre, where star formation is occurring most vigorously, is forcing gas out in what is called a "Champagne flow". Dr. John Richer of the Cavendish Laboratory at the University of Cambridge (UK) says: "It's taken a long time to get to this point - the first science data from HARP/ACSIS - but it's been worth the wait. For the first time, we can make large-scale maps of the warm gas in molecular clouds and so begin to understand in detail the complex and spectacular processes which occur when stars form." HARP (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. Dr. Jane Buckle of the Cavendish Laboratory says: "Commissioning HARP and ACSIS took a lot of hard work and dedication, particularly from the JAC, the Cavendish Laboratory and UK ATC staff, but the new spectral imaging capabilities at the JCMT make this a very exciting time for star formation research." Dr. Bill Dent of the Royal Observatory Edinburgh says:" We often find gas clouds many tens of light-years across containing hundreds of stars all forming simultaneously. With this new system, we can map the structure and measure the speed of the gas that's forming all these new stars and, furthermore, do a chemical analysis, perhaps looking for regions rich in rare and exotic molecules. Before HARP/ACSIS arrived, it was just not possible to study and understand whole clouds in this way." "It's really exciting to see science pouring out of this instrument at long last," says Professor Richard Hills of the Cavendish Laboratory, the Project Scientist for HARP. And Dr. Harry Smith, HARP Project Manager, says: "It was great to work on what turned out to be a world-beating facility instrument." Dr. John Richer has used the JCMT for 19 years to make spectroscopic observations of molecular clouds. "It used to be a painstaking and slow process. Now with HARP's 16 sensitive detectors, we can take data at a much more rapid rate and begin to answer much more ambitious questions about the formation of new star systems. HARP/ACSIS is revolutionising our view of star formation in the galaxy," said Richer. Professor Gary Davis, Director of the JCMT, said "ACSIS and HARP have been developed over the last several years by a network of instrumentation laboratories around the world. By making use of the very latest technologies, we have introduced a new capability at the observatory which cannot be matched anywhere in the world. Astronomers will now be able to study star-forming regions such as Orion with unprecedented scope and detail. We are really excited about the science that these instruments will make possible for the first time." The James Clerk Maxwell Telescope is at 15-metres diameter the largest dish operating at submillimetre wavelengths in the world. Located on Mauna Kea in Hawaii, it was opened in 1987. It is operated by the Joint Astronomy Centre in Hilo, Hawaii, and funded jointly by the United Kingdom (Science and Technology Facilities Council), Canada (National Research Council, NRC) and the Netherlands (Organization for Scientific Research, NWO). http://www.jach.hawaii.edu/JCMT/ 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). Images
This image shows the carbon-monoxide content at the heart of this Giant Molecular Cloud. The bright region in the image is the Orion Nebula itself which is visible to the naked eye and is where the majority of the star formation is taking place. One can see that the gas (which really does look like clouds!) extends over vast regions and helps to "feed" the star formation. The image is over 30 light-years from top to bottom. The region shown is approximately the size of two full moons on the sky.
The image on the right shows Orion obtained with HARP/ACSIS on the James Clerk Maxwell Telescope (JCMT) in the submillimetre wavelengths, while the image on the left shows a comparison image obtained with WFCAM on the United Kingdom Infrared Telescope (UKIRT) in the infrared wavelengths. The JCMT submillimetre image shows the dense cloud material from which new stars form. The UKIRT infrared image shows the young stars and the heated gas filaments surrounding them. Both telescopes are operated by the Joint Astronomy Centre in Hilo, Hawaii. The bar corresponds to four light years, which is equal to the distance from our Sun to the nearest star.
The data cube - two spatial dimensions and one wavelength dimension. For each image of the Orion Nebula we get multiple wavelength slices.
HARP at the James Clerk Maxwell Telescope in Hawaii.
HARP on the James Clerk Maxwell Telescope Nasmyth platform.
ACSIS is housed in four temperature-controlled racks of electronics (front view).
The James Clerk Maxwell Telescope on Mauna Kea, Hawaii.
This movie takes the observer through the data cube and gives a feel of how the gas is moving. The movie starts with clouds in the southern region, and then shows them progressively more towards the north as it steps through the wavelength slices. This reveals an expansion of gas. Gas to the south is moving towards the observer, while to the north it is moving away from the observer.
Notes for editorsThe Orion images
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/ The UK ATCThe UK Astronomy Technology Centre is located at the Royal Observatory, Edinburgh (ROE). It is a scientific site belonging to the Science and Technology Facilities Council. The mission of the UK ATC is to support the mission and strategic aims of the Science and Technology Facilities Council and to help keep the UK at the forefront of world astronomy by providing a UK focus for the design, production and promotion of state of the art astronomical technology. 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 Trade and Industry. 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. ContactsPlease note that it is best to contact these individuals by email.
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