Scientists prove stars are born more rapidly than was previously thought
Scientists, including astronomers at the University of Sussex, have presented the first conclusive evidence that stars formed most rapidly about 10 billion years ago, or about three to four billion years after the Big Bang, and that the rate of star formation is much faster than was thought.
Using the European Space Agency's Herschel Space Observatory to study distant objects with the Spectral and Photometric Imaging Receiver (SPIRE) camera, researchers have discovered that galaxies are forming stars at a tremendous rate and have large reservoirs of gas that will power the star formation for hundreds of millions of years.
The data from Herschel and SPIRE is helping to produce a map of the universe as it was around eight billion years ago. The map project, HerMES (Herschel Multi-tiered Extragalactic Survey), is led by Professor Sebastian Oliver at the University of Sussex. He said: 'We are really blown away by the tremendous capability of Herschel to probe the distant universe. This work gives us a real handle on how the cosmos looked early in its life."
His colleague, Dr Isaac Roseboom, said: "It was amazing and surprising to see the Herschel-SPIRE observations uncover such a dramatic population of previously unseen galaxies".
The key to the new results is the recent discovery of a new type of extremely luminous galaxy in the early Universe. These galaxies are very faint in visible light, as the newly-formed stars are still cocooned in the clouds of gas and dust within which they were born. This cosmic dust, which has a temperature of around -232 degrees C, is much brighter at the longer, far infrared wavelengths observed by the Herschel satellite.
Herschel is the first telescope with the capability to detect these galaxies at the peak of their output. With these Herschel observations, focused on around 70 galaxies in the constellation of Ursa Major, the scientists acquired the missing piece of evidence to confirm that these galaxies represent a crucial episode in the build up of large galaxies around us today, such as our own Milky Way.
This results was one of a number published in a special edition of the journal Monthly Notices of the Royal Astronomical Society focusing on results from Herschel. The special edition was the brain child of Prof. Oliver and included 17 Herschel papers including 12 from his team.
Notes for editors
SPIRE is one of three instruments on the Herschel Space Observatory, and has both a camera and a spectrometer. The camera operates across three wavelength bands centred on 250, 350 and 500 µm, while the spectrometer covers the wavelength range 194-672 µm. SPIRE is a UK-led instrument, and involves a number of UK institutions: University of Sussex, Cardiff University, Imperial College London, UK Astronomy Technology Centre, Rutherford Appleton Laboratory and University College London's Mullard Space Science Laboratory.
HerMES (Herschel Multi-tiered Extragalactic Survey) is the largest of Herschel's Key Programmes, with 900 hours of observation currently allocated, and is carried out by the SPIRE high-redshift Specialist Astronomy Group. HerMES will map large regions of the sky using cameras that are sensitive to infrared radiation, and is expected to discover over 100 thousand galaxies. The light from most of these galaxies will have taken more than 10 billion years to reach us, which means we will see them as they were 3 or 4 billion years after the big bang. Since the cameras are detecting infrared radiation they see star formation that is hidden from conventional telescopes. It is expected that the SPIRE cameras will catch many of the galaxies at the moment they are forming most of their stars.
Herschel was recently listed at number 7 in Time magazine as one of the most important inventions of the year.
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Visit http://www.hermes.sussex.ac.uk/ for the most recent information about HerMES
The UK Herschel Outreach site is http://herschel.cf.ac.uk/
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