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The UK-led SPIRE instrument on board the Herschel Space Observatory has made its first astronomical observations, with spectacular results. The first SPIRE images, together with first light observations from the other two Herschel instruments, are released today (Friday 10th July) by the European Space Agency (ESA)

M66 and M74
Credit:ESA

The SPIRE camera responds to light at wavelengths between 250 and 500 microns (500-1000 times longer than the wavelength of visible light). It is designed to look for emission from clouds of dust in regions where stars are forming in our own and other galaxies.

On June 24, SPIRE was able to observe the sky for the first time. The telescope was trained on two galaxies to get a first impression of what the instrument could see. The results were better than anyone expected from first observations, made before any attempt to set up the instrument or to tune the image-making software. The target galaxies showed up prominently, providing by far the best images yet seen at these wavelengths. Many other, more distant, galaxies were also seen in the field of view.

M66 SPIRE 250 microns and M66 Spitzer 160 microns
Credit:SPIRE: ESA, Spitzer: NASA

The images show two galaxies, M66 and M74, at a wavelength of 250 microns. The images trace emission by dust in clouds where star formation is active, and the nucleus and spiral arms show up clearly. Dust is part of the interstellar material that fuels star formation, and these images effectively show the reservoirs of gas and dust that are ready to be turned into stars in the galaxies. Very significantly, the frames are also filled with many other galaxies which are much more distant and only show up as point sources, and there are also some extended structures, possibly due to clouds of dust in our own galaxy.

These images have given astronomers an exciting foretaste of the important scientific studies planned with SPIRE: the instrument will look at star formation close up in our own galaxy and in nearby galaxies, and it will search for star-forming galaxies in the very distant Universe. Because these galaxies are so far away, their light has taken a very long time to reach us, so by detecting them we are looking into the past and learning how and when galaxies like the Milky Way were formed.

M74 SPIRE 250 microns and M74 Spitzer 160 microns
Credit:SPIRE: ESA, Spitzer: NASA

Professor Matt Griffin of Cardiff University, who is the SPIRE Principal Investigator, said: “These quick first light observations have produced dramatic results when we consider that they were made on day one. Astronomers planning to use SPIRE are delighted because they can see straight away that the main scientific studies planned with the instrument are going to work extremely well. In fact all three instruments on Herschel have now shown what they can do, and the results are spectacular all round.”

Professor Robert Kennicutt of Cambridge University, who will use Herschel to study nearby galaxies, including the two selected for SPIRE first light, said: “I am thrilled by the quality of these first images from SPIRE. They reveal the cold dust and star formation in these galaxies in stunning detail, and are a sneak preview of future observations that promise to revolutionise our understanding of star formation in the Universe.”

SPIRE images of M74 at three different wavelengths
Credit:ESA

Dr. Laurent Vigroux of CEA/IRFU Saclay and Institut d'Astrophysique de Paris, who is the Co-Principal Investigator for the SPIRE Team, said: “We have dreamed of seeing such images for a very long time, more than ten years. And they are an achievement: the first real images in the far infrared, opening a new window in astronomy. These images are the start of another ten years or more of work to exploit all the scientific results that SPIRE will produce."

Professor Keith Mason, Chief Executive of the Science and Technology Facilities Council (STFC), which provides the UK funding for Herschel, said, “We are delighted to see that the SPIRE instrument is working so effectively and returning such detailed, high quality images. UK researchers have put a great deal of hard work into this complicated camera and these amazing new images are proof of the skill and expertise we have here in the UK and why we continue to be at the forefront of new technology development for Europe’s growing space exploration activities.”

Notes for editors

Images

SPIRE images of two galaxies, M66 and M74, at a wavelength of 250 microns.
The images trace emission by dust in clouds where star formation is active, and the nucleus and spiral arms show up clearly.

M66 SPIRE 250 microns (ESA) and M66 Spitzer 160 microns (Credit: NASA)

M74 SPIRE 250 microns (ESA) and M74 Spitzer 160 microns (Credit: NASA)
To illustrate the advance made by Herschel, the pictures compare the SPIRE images with the best previous images of these galaxies in this part of the spectrum, made by NASA’s Spitzer space observatory at a wavelength of 160 microns. The huge difference in image quality is attributable to the much larger Herschel telescope (3.5 m compared to Spitzer’s 85 cm) and to SPIRE’s highly sensitive detectors.

SPIRE images of M74 at three different wavelengths (equivalent to three different colours).
These images are scaled to show up the extended nature of the galaxies and the rich detail in the background sky. The image quality is best at 250 microns because telescopes produce sharper images at their shortest wavelengths. By combining the three images, astronomers can measure the properties of the emitting dust and identify the nature of the many distant galaxies that also appear in the pictures

Herschel and SPIRE

The European Space Agency’s Herschel satellite carries the largest telescope to be flown in space and will study the Universe at far infrared wavelengths. It will reveal the early stages of star birth and galaxy formation; it will examine the composition and chemistry of comets and planetary atmospheres in the Solar System; and it will examine the star-dust ejected by dying stars into interstellar space which form the raw material for planets like the Earth.

The SPIRE instrument has been built by a consortium of 18 institutes in eight countries (UK, France, Italy, Spain, Sweden, USA, and China), led by Prof. Matt Griffin of Cardiff University. The instrument was assembled at the STFC’s Rutherford Appleton Laboratory in the UK.

Galaxies in SPIRE first light observations

M74 (also known as NGC 628) is a face-on spiral galaxy located about 24 million light years from Earth in the constellation Pisces. In visible light, produced mainly by the stars within the galaxy, we see a bright nucleus and well-defined spiral arms that contain many small, bright regions young massive stars have formed recently. The submillimetre SPIRE images trace the cold dust between the stars, and the spiral arms appear much more enhanced. They also contain many faint dots that are actually distant galaxies in the background. These galaxies also contain dust that radiates at submillimetre wavelengths, but because they are much further away, we cannot actually see the structure in the galaxies.

M66 (also known as NGC 3627) is a barred spiral galaxy located about 36 million light years away in the constellation Leo. The bar is a structure made out of stars, gas, and dust. In visible light, we see the starlight tracing both the bar and the spiral arms attached to the bar, but we also see many dark lanes in the starlight caused by interstellar dust that absorbs the starlight. In the submillimetre SPIRE images, we see the thermal radiation from that dust. SPIRE shows show that most of the dust is located in the center and near the ends of the bar, with additional dust found in the spiral arms. The bar exerts forces on other objects within the disk of the galaxy and causes gas and dust to accumulate in the center and near the ends of the bar, which is why these locations look so bright in the SPIRE image. Again we see many other galaxies within the field of view.

Herschel Mission timeline:

• Herschel and Planck were launched on an Ariane 5 from Europe’s Spaceport in Kourou, French Guiana, on 14 May 2009.
• Commissioning Phase: In the first few days after launch basic spacecraft checks were done.
• One to two weeks after launch, the Herschel scientific instruments were switched on for the first time and detailed commissioning of the instruments began. This will continue until around the end of July. The satellite is already nearing its operational orbit, about 1.5 million km from the Earth.
• Performance Verification Phase: This will begin about 60 days after launch, and will involve tests to ensure that the instrument operational modes and scientific data processing software are thoroughly checked and optimised.
• Science Demonstration Phase: About 150 days into the mission, spacecraft and instrument testing will be complete and comprehensive trial scientific observations will begin, involving execution of a selection of different kinds of observations and processing the data to produce scientific results.
• Routine Operations Phase: About six months after launch, routine operations will begin, and will last for at least three years. The observational programmes for the first 18 months have already been selected.

UK Participation in Herschel

The UK contribution to Herschel includes leadership of the international consortium that designed and built the SPIRE instrument. The UK SPIRE team is also responsible for the development of software for instrument control and processing of the scientific data, and leads the in-flight testing and operation of SPIRE. The Herschel programme in the UK is funded by the Science and Technology Facilities Council.

SPIRE comprises a three band imaging photometer and an imaging Fourier transform spectrometer and has been designed and built by a consortium of institutes including a number from the UK (Cardiff University; Imperial College, London; the Mullard Space Science Laboratory; the University of Sussex; and STFC’s Rutherford Appleton Laboratory and UK Astronomy Technology Centre). The UK is also leading the development of software for controlling the instrument from the ground and processing the data to produce scientific results. The SPIRE Operations Centre, responsible for delivering all instrument software to ESA, and for day-to-day instrument monitoring, operation, and calibration, is located at the Rutherford Appleton Laboratory with contributions from the Imperial College and Cardiff groups. The UK SPIRE institutes, together with astronomers in many other UK universities, are also strongly involved in the Herschel scientific programmes which have already been selected for the first 18 months of Herschel observations, and cover a wide range of science topics from our own solar system to the most distant galaxies.

Contact

• Julia Short
  Press Officer
  STFC
  Tel: + 44 (0)1793 442012
  
  
• Prof. Matt Griffin
  Herschel-SPIRE Principal Investigator
  School of Physics and Astronomy
  Cardiff University
  Tel: +44 (0)29 2087 4203
  
  
• Prof. Robert Kennicutt
  Cambridge University
  Institute of Astronomy
  University of Cambridge
  Tel: +44 (0)1223-765844
  
  
• Dr Laurent Vigroux
  Institut d'Astrophysique de Paris
  Tel: +33 1 44 32 80 00