A 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!"
Additional information and images about the JCMT Legacy Survey can be found at http://outreach.jach.hawaii.edu/pressroom/2008_legacysurvey1/.
FOR MORE INFORMATION:
Dr Jennifer Hatchell (GBS Team)
University of Exeter, UK
Desk: +44 1392-725516
Prof. Christine Wilson (NGLS Team)
McMaster University, Canada
Desk: +1 905-525-9140 (x27483)
Dr Floris van der Tak (SLS Team)
Desk: +31 50-363-8753
Dr Antonio Chrysostomou
Joint Astronomy Centre
Desk: +1 808-969-6512
Prof. Gary Davis
Joint Astronomy Centre
Desk: +1 808-969-6504