Combined Herschel images reveal hidden Galaxy
DR EMILY BALDWIN
Posted: October 02, 2009
Combining the observing power of the SPIRE and PACs cameras, the Herschel Space Observatory has produced stunning new images of interstellar material and star-forming regions in our home Galaxy.
The spectacular new pictures were taken during the first trial run of using the two instruments at the same time while Herschel was directed towards the centre of the Milky Way in the Southern Cross. The targeted region was already known to host a variety of structures and temperatures, making it the ideal candidate for testing the instruments' capabilities.In this image the SPIRE and PACS images have been combined into a single composite; here the blue denotes 70 microns, the green 160 microns, and the red is the combination of the emission from all three SPIRE bands at 250/350/500 microns. Image: ESA and the SPIRE & PACS Consortia.
The SPIRE camera responds to light at wavelengths between 250 and 500 microns and PACS covers wavelengths between 70 and 170 microns, and together they provide detailed images in five different far infrared colours. The results reveal 'hidden' material and provide mass, temperature and compositional data about the material, some of which is collapsing to form new stars.
"We had high hopes for this kind of observation with Herschel, using the combined power of the two cameras to see the Galaxy as never before," says SPIRE Principal Investigator Matt Griffin of Cardiff University. "It’s great to see that the observations work so well from a technical point of view, and that the scientific results are so spectacular. It appears that star formation in the Galaxy is a very turbulent process."SPIRE (left) and PACS (right) parallel mode images obtained during the performance verification phase. Image: (left) ESA and the SPIRE consortium, (right) ESA and the PACS consortium.
The images cover an area measuring roughly two by two degrees, and reveal an extremely rich reservoir of cold material in a state of previously unsuspected turmoil that is condensing and collapsing into new stars. Young stars at all stages of development are revealed in chains strung out across the region. The impressive colour coding of the images differentiates material that is extremely cold – less than 10 degrees Kelvin – in red, from that which is warmer. The composite image therefore easily identifies star-forming filaments that would be very difficult to isolate from a map made at a single far-infrared or submillimetre wavelength. This type of observation is especially important in a very crowded field like this, which is likely to include many molecular clouds along the line of sight.
Herschel will systematically survey other areas of the Milky Way in this fashion, to provide new insight into the mechanisms of star formation in a way that has never before been achieved. Using the instruments simultaneously also maximises the coolant required to maintain Herschel's low operating temperatures and which ultimately defines the lifetime of the mission.
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