Imperial physicists take first peek into dusty galaxies with Herschel space telescope

First images from SPIRE 'camera' released<em> - News</em>

By Danielle Reeves
Friday 10 July 2009

The UK-led SPIRE 'camera' on the Herschel space telescope has taken its first test images of two galaxies in the constellations of Pisces and Leo, with spectacular results.

The images were processed at the Rutherford Appleton Laboratory by a small team including two Imperial physics researchers. Imperial's physicists played a key role in conceiving, designing and developing the SPIRE instrument over the last 20 years, and more recently have been instrumental in developing the software to convert masses of raw data from space into the pictures released by the European Space Agency today. These provide a never-before-seen insight into the cold dusty regions of galaxies, where stars are formed. Over the next 3 years Imperial physicists will study images like these from Herschel to further their understanding of some of the most fundamental processes in the Universe.

Dr Dave Clements from the Department of Physics, who leads Imperial's Herschel team, explains the significance of these initial images: "These first test observations are fantastic – they provide by far the clearest images ever at these long wavelengths, showing the cold dusty parts of these two nearby galaxies in great detail. This is an extremely exciting start to the Herschel mission. It demonstrates just how good SPIRE is compared to everything that's come before. We're about to enter a new world of far-infrared astronomy – the fire-hose of data and new insights into how the universe works is about to start."

The M66 galaxy as seen by Herschel

Featuring in the newly released images are Messier 66 (M66) and Messier 74 (M74), two spiral galaxies approximately 36 million and 31 million light years from Earth, respectively. The images show the emission of light with a wavelength of 250 microns – much longer than that of visible light - from dust clouds in these galaxies where star formation is active.

Unlike previous images captured of this long wavelength light, the shape of both galaxies is shown in new high resolution, with the outer spiral arms and the central nucleus of both galaxies clearly visible. This is an exciting development because it means researchers can see clearly the locations of reservoirs of dust and gas that are ready to be turned into stars in the galaxies.

In addition the frame of each picture is also filled with an array of many other galaxies in the far distance, behind M66 and M74 in the foreground. This is of great interest to the Herschel team because it demonstrates that SPIRE can probe cosmological distances and study the role of dust dominated galaxies – objects where dust absorbs most of the starlight and reprocesses it into the far-infrared, producing the Cosmic Infrared Background radiation.

The test images were taken on 24 June when SPIRE was able to observe the sky for the first time, just over a month after Herschel was launched into space strapped to an Ariane V rocket. The results are better than anyone expected from first observations, and they were taken before the image-making software had been fine-tuned or the instrument had been fully set up.

Over the next three months SPIRE and the other instruments onboard Herschel will undergo a period of further tests and calibration, before coming into full use around October 2009.

SPIRE will allow researchers at Imperial and other institutions around the world to look at star formation close-up in our own galaxy, the Milky Way, and the surrounding galactic neighbourhood. It will also allow them to search for star-forming galaxies in the very distant universe, which effectively provides the opportunity to look back into the past and see how galaxies like ours were formed.

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