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Double asteroid belt in Solar System clone

...Spitzer observations have discerned two rocky asteroid belts and an icy outer ring surrounding our Sun’s doppelgänger Epsilon Eridani that could have been shaped by evolving planets..

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Fireball captured by Canadian cameras

...for the second time this year The University of Western Ontario’s Meteor Group has captured rare footage of a meteor streaking across the sky and possibly falling to the ground...

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ESA gravity mission slips to 2009

...the launch of Europe’s Gravity field and steady-state Ocean Circulation Explorer (GOCE) has slipped to February 2009 due to ongoing technical faults with its launcher..

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Video archive

STS-120 day 2 highlights

Flight Day 2 of Discovery's mission focused on heat shield inspections. This movie shows the day's highlights.


STS-120 day 1 highlights

The highlights from shuttle Discovery's launch day are packaged into this movie.


STS-118: Highlights

The STS-118 crew, including Barbara Morgan, narrates its mission highlights film and answers questions in this post-flight presentation.

 Full presentation
 Mission film

STS-120: Rollout to pad

Space shuttle Discovery rolls out of the Vehicle Assembly Building and travels to launch pad 39A for its STS-120 mission.


Dawn leaves Earth

NASA's Dawn space probe launches aboard a Delta 2-Heavy rocket from Cape Canaveral to explore two worlds in the asteroid belt.

 Full coverage

Dawn: Launch preview

These briefings preview the launch and science objectives of NASA's Dawn asteroid orbiter.

 Launch | Science

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JCMT sees the dark hearts of bright galaxies

Posted: 05 November, 2008

European astronomers using the James Clark Maxwell Telescope (JCMT) have gained important information on what are known as Ultraluminous Infrared Galaxies (ULIRGs), galaxies with a huge energy output but which are obscured by their massive dust and gas clouds.

Astronomers believe that this class of galaxy was much more common in the younger Universe than it is now, with their impressive energy output attributed to extremely rapid conversion of gas into young, luminous stars and to energetic processes associated with supermassive black holes. Using the HARP receiver on the JCMT, a team of astronomers from Wales, The Netherlands and Germany directly probed the physical conditions in the active inner regions of a number of ULIRGs by penetrating the thick dusty veil surrounding the galaxies and observing the submillimetre radiation.

Spectrum of hydrogen cyanide in a ULIRG obtained with the JCMT and its HARP receiver. The background image shows UGC5101 as observed with the ACS on board the Hubble Space Telescope and shows dust clouds obscuring the most luminous parts of the galaxy which can be seen as a red-brown band. Image: NASA, ESA, the Hubble Heritage STScI/AURA-ESA/Hubble Collaboration, and A. Evans, University of Virginia, Charlottesville/NRAO/Stony Brook University.

"The submillimetre radiation observed by the JCMT can penetrate the dust shroud obscuring the nuclear regions of the ULIRGs, but the spectral lines emitted from these regions are still very faint," says Dr Papadopoulos from Bonn University. "Therefore, we had to use the JCMT and its sensitive HARP receiver for up to 12 hours under very good atmospheric conditions, to detect just a single line in a single galaxy."

Among the molecular fingerprints that the team has observed are spectral lines of warm and dense carbon monoxide (CO) and of the formyl ion (HCO+). However, the most important spectral line detected is hydrogen cyanide (HCN), which originates from warm, dense and highly toxic hydrogen cyanide gas in the most active regions of the ULIRGs. These are the first spectra of this type from a substantial set of ULIRGs, and are surprisingly difficult to detect in many of these extreme objects. When interpreted together with the rest of the data, it becomes obvious that this spectral line probes the most extremely dense gas, the very immediate fuel of the massive star formation in these objects.

"Unlike other spectral lines which probe more remote gaseous regions in these galaxies which may not be actively forming stars, the hydrogen cyanide intensity changes dramatically from galaxy to galaxy," says Paul van der Werf of Leiden University in The Netherlands. "This depends on, and reveals, the intense gravitational tides and their effects on the densest of the gas phases in the centres of the ULIRGs."

The team is continuing its study of ULIRGs with the JCMT by observing the hot dense gas associated with the formation of young stars in these galactic powerhouses. "Even future satellites will not be able to supply us with all the information we need to probe the conditions within these galaxies: the JCMT with its large collecting area provides essential pieces in the puzzle," adds Kate Isaak of Cardiff University.