Planck space observatory unveils the coldest regions of our galaxy
17 Mar 2010
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Giant filaments of cold dust stretching through the coldest regions of our Galaxy are revealed in new images, released today (17th March), from ESAs Planck satellite.

 

Planck images a galactic web of cold dust (Credit: ESA / HFI Consortium / IRAS)

 

Press release: 17 March 2010

Giant filaments of cold dust stretching through the coldest regions of our Galaxy are revealed in new images, released today (17th March), from ESA’s (European Space Agency) Planck satellite. Analysing these structures could help to determine the forces that shape our Galaxy and trigger star formation. The images are a scientific by-product of a mission which will ultimately provide the best picture ever of the early Universe.

Dr David Parker, Director of Space Science and Exploration at the British National Space Centre (BNSC), said, “Less than a year since it was launched, Planck is producing some spectacular results. The Planck spacecraft is just one of a family of cutting edge scientific missions in which the UK is already playing a major role. I'm looking forward to fresh discoveries and continued involvement in such exciting missions with the forthcoming creation of a UK executive space agency.”

ESA’s Planck satellite – the first European mission designed to study the Cosmic Microwave Background (CMB) - has begun the second of four full-sky surveys, which will ultimately provide the most detailed information yet about the size, mass, age, geometry, composition and fate of the Universe. Although the primary goal of Planck is to map the CMB, by surveying the entire sky with an unprecedented combination of frequency coverage, angular resolution, and sensitivity, Planck will also provide valuable data for a broad range of studies in astrophysics. This is clearly demonstrated in the new images which trace the cold dust in our Galaxy and reveal the large-scale structure of the interstellar medium filling the Milky Way.

One of the key advantages of Planck is its ability to measure the temperature of the coldest dust particles and locate the coldest dusty clumps in the Galaxy, areas where star formation is about to occur. Image 1 demonstrates how Planck measures this cold dust: reddish tones correspond to temperatures as cold as 12 degrees above absolute zero, and whitish tones to much warmer ones (a few tens of degrees) in regions where massive stars are currently forming. As the clumps shrink, they become denser and better at shielding their interiors from light and other radiation. This allows them to cool more easily and collapse faster. Planck excels at detecting these dusty clumps across the whole sky and contributes the crucial information required to measure accurately the temperature of dust at these large scales.

“What makes these structures have these particular shapes is not well understood,” says Jan Tauber, ESA Project Scientist for Planck. The denser parts are called molecular clouds while the more diffuse parts are ‘cirrus’. They consist of both dust and gas, although the gas does not show up directly in this image. There are many forces at work in the Galaxy to help shape the molecular clouds and cirrus into these filamentary patterns. For example, on large scales the Galaxy rotates, creating spiral patterns of stars, dust, and gas. Gravity exerts an important influence, pulling on the dust and gas. Radiation and particle jets from stars push the dust and gas around on smaller scales, and magnetic fields also play a role, although to what extent is presently unclear.

The space between stars is not empty but rather is filled with clouds of dust and gas, intimately mixed together and known as the “interstellar medium”. Image 2, covers the same region as image 1: about 55 degrees across and looking in the direction of the centre of our Galaxy. The plane of the Galaxy is seen as the horizontal band across the bottom of the image. Above the plane, the filamentary structure of the interstellar medium in the solar neighbourhood (within a few hundred light years of the Sun) can be seen.

 
Filamentary structures are apparent at large and small-scales in the Milky Way.
(Credit: ESA / HFI Consortium. Credits for inset: ESA / SPIRE and PACS consortia / P. André (CEA Saclay) for the Gould’s Belt Key Programme Consortium)

The image on the left in image 2 shows a typical “stellar nursery” (about 3 degrees across) in the constellation of Aquila, recently imaged by the Herschel Space Observatory. The filamentary structures seen at the smallest scales by Herschel are strikingly similar in appearance to those seen at the largest scales by Planck.

The richness of the structure that is observed, and the way in which small and large scales are interconnected, provide important clues to the physical mechanisms underpinning the formation of stars and of galaxies. This example illustrates the synergy between Herschel and Planck; together these missions are imaging both the large-scale and the small-scale structure of our Galaxy.

Dr David Clements from Imperial College London, said, "These wonderful new images from Planck clearly show its power for revealing new things about the universe. We always knew there would be a lot of great new science found as we peeled away the layers of the cosmic onion to reach the microwave background, and these results demonstrate that happening in our own galaxy. What I hadn't really grasped was just how beautiful the Planck foreground images were going to be!"

Tom Bradshaw from the Science and Technology Facilities Council’s Rutherford Appleton Laboratory (RAL) added, “Planck is a satellite designed to measure the temperature of deep space to unprecedented accuracy. The technology to achieve this has been under development for over 15 years. A significant part of this was developed in the UK. After all the hard work that has been put into what is probably one of the most complex satellites ever flown, it is gratifying to see such stunning images that will help us understand our place in the universe.”


Notes to editors

Images and captions

  • Image 1: Planck’s ability to measure the temperature of the coldest dust particles will provide an important indicator of the physical processes at play in the interstellar medium, and in regions of star formation.

    The image above covers a portion of the sky about 55 degrees across. It is a three-colour combination constructed from Planck’s two shortest wavelength channels (540 and 350 micrometres, corresponding to frequencies of 545 and 857 GHz respectively), and an image at 100 micrometres obtained with the Infrared Astronomical Satellite (IRAS). This combination effectively traces the dust temperature: reddish tones correspond to temperatures as cold as 12 degrees above absolute zero, and whitish tones to significantly warmer ones (a few tens of degrees above absolute zero) in regions where massive stars are currently forming. Overall, the image shows local dust structures within 500 light years of the Sun.

    This Planck image was obtained during the first Planck all-sky survey which began in mid-August 2009. By mid-March 2010 more than 98% of the sky had been observed by Planck. Because of the way Planck scans the sky 100% sky coverage for the first survey will take until late-May 2010.

    Credit: ESA and the HFI (High Frequency Instrument) Consortium / IRAS

  • Image 2: Filamentary structures are apparent at large-scales (as shown in this Planck image) and small-scales (as seen on the left, a Herschel image of a region in the constellation of Aquila) in the Milky Way.

    This Planck image, covering a portion of the sky about 55 degrees across, was obtained by the Planck High Frequency Instrument at a wavelength of 350 micrometres (corresponding to a frequency of 857 GHz). The bright horizontal band corresponds to the plane of our spiral Galaxy, which is seen in cross-section from our vantage point. The colours in the Planck images represent the intensity of heat radiation by dust.

    This Planck image was obtained during the first Planck all-sky survey which began in mid-August 2009. By mid-March 2010 more than 98% of the sky had been observed by Planck. Because of the way Planck scans the sky 100% sky coverage for the first survey will take until late-May 2010.

    Credit: ESA / HFI Consortium. Credits for inset: ESA / SPIRE and PACS consortia / P. André (CEA Saclay) for the Gould’s Belt Key Programme Consortium.

  • Image 3: This Infrared Astronomical Satellite (IRAS) map depicts the sky at 100 µm. The red box indicates the region covered by a Planck image (see "New Planck images trace cold dust and reveal large-scale structure in the Milky Way"). The projection for this map is orthographic.

    Credit: ESA / IRAS

More info about Planck and new images

Planck maps the sky in nine frequencies using two state-of-the-art instruments, designed to produce high-sensitivity, multi-frequency measurements of the diffuse sky radiation: the High Frequency Instrument (HFI) includes the frequency bands 100 – 857 GHz (corresponding to wavelengths of 3 – 0.3 mm), and the Low Frequency Instrument (LFI) includes the frequency bands 30-70 GHz (corresponding to wavelengths of 10 – 4 mm).

The first Planck all-sky survey began in August 2009 and is 98% complete (as of mid-March 2010). Because of the way Planck surveys the sky, the last bit of the first scan will be completed by late-May 2010. Planck will gather data until the end of 2012, during which time it will complete four sky scans. A first batch of astronomy data, called the Early Release Compact Source Catalogue, is scheduled for release in January 2011. To arrive at the main cosmology results will require about two years of data processing and analysis. The first set of processed data will be made available to the worldwide scientific community towards the end of 2012.

ESA’s Herschel space telescope can be used to study cold regions in detail, but only Planck can find them all over the sky. Launched together in May 2009, Planck and Herschel are both studying the coolest components of the Universe. Planck looks at large structures, while Herschel can make detailed observations of smaller structures, such as nearby star-forming regions.

The HFI data were recorded as part of Planck’s first all-sky survey at microwave wavelengths. As the spacecraft rotates, its instruments sweep across the sky. During every rotation, they cross the Milky Way twice. Thus, in the course of Planck’s mission to precisely map the afterglow of the big bang, it is also producing exquisite maps of the Galaxy.

UK role in Planck

The UK is playing a major role in the Planck mission, with funding from the Science and Technology Facilities Council (STFC). The UK is the second largest financial contributor to the ESA Science Programme which builds and launches space missions such as Planck using leading-edge technology from the UK space industry. In addition, STFC has invested £17.4M to build instrumentation for Planck.

A number of UK institutes and companies form part of the consortium building the two focal plane instruments, HFI and LFI. The Jodrell Bank Observatory at The University of Manchester has produced critical elements of the LFI receiver modules. Cardiff University, STFC RAL and SEA have been involved with hardware development for HFI, while various UK research groups including Imperial College London and University of Cambridge form the London Planck Analysis Centre and Cambridge Planck Analysis Centre. These groups are involved with data analysis and simulation for the HFI data analysis and simulation software.

More information can be found in the Planck briefing document (PDF-66kB) (link opens in a new window).

Links

Contacts

  • Julia Short
    BNSC Press Office
    Tel: +44 (0)1793 442012

  • Chris North
    School of Physics and Astronomy
    Cardiff University
    Tel: +44 (0)29 208 70537 or 76403

  • Jan Tauber
    Planck Project Scientist
    Research and Scientific Support Department
    Directorate of Science and Robotic Exploration
    European Space Agency

For more information please contact: RAL Space Enquiries

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