Astronomers working on BLAST (Balloon-borne Large-Aperture Sub-millimeter Telescope) study have determined that dust-enshrouded galaxies several billion light years away hide about half of the starlight in the Universe from Earth's view.
Peering up into the night sky gives Earth-bound observers only half of the cosmic history of how stars are born. Stars form when clouds of gas and dust coalesce and ignite, releasing energy into space and causing the star to shine. But the same dust that plays a crucial role in star formation also obscures our view of the young stars' light, thereby hiding their existence. However, the dust itself, warmed by starlight, emits light at far-infrared and submillimetre wavelengths, which are invisible to the human eye, but visible to the sensitive detectors aboard BLAST. Studying these wavelengths provides astronomers with the far infrared luminosity of each galaxy and, ultimately, an estimate the rate at which the stars formed.
Designed by a multi-national collaboration, including Canada, the U.S. and the U.K, the BLAST mission flew on an 11-day mission in 2006 aboard a huge helium balloon, which lofted the 2-metre telescope nearly 37 kilometres above Antarctica. BLAST circled the frozen continent above 99.7% of Earth's atmosphere, and produced a wealth of data virtually unattainable from the ground. In just days, BLAST found 10 times the number of submillimetre wavelength galaxies that ground-based telescopes have detected in the past decade. "BLAST has given us a new view of the Universe, enabling the BLAST team to make discoveries in topics ranging from the formation of stars to the evolution of distant galaxies," says University of Toronto Professor Barth Netterfield.
"Over the last decade, submillimetre telescopes on the ground have produced several 'black and white' images no larger than the size of a fingernail at the end of your outstretched arm," says Dr. Ed Chapin at the University of British Columbia. "In a single 11-day flight BLAST has taken a huge leap forward, producing colour images the size of your hand."
Star formation in the Milky Way
BLAST is uniquely capable of studying the earliest stages of star formation locally in the Milky Way, our own galaxy. The BLAST telescope produced this image of star formation in the southern constellation of VELA during its 11-day balloon flight over Antarctica in December 2006. The 50-square degree map (about 250 times as wide as the area of the full Moon as seen in the night sky) shows the submillimetre emission from thousands of stellar nurseries. Colour is an indicator of temperature. Blue areas are warmed above minus 253 Celsius (20 Kelvin) by recent or ongoing star formation. Orange regions, where the gas and dust are not being warmed by massive young stars, have cooled to around minus 261 Celsius (12 Kelvin). The structure of the clouds is the result of the complex interplay between energetic winds from the hot young stars, gravity and magnetic fields.
(Credit: The BLAST Collaboration)
The Canadian Connection
The Canadian team from the Universities of British Columbia and Toronto provided the BLAST gondola, pointing system, electronics and software, and has led the data analysis.
BLAST has also acted as a pathfinder for the SPIRE (Spectral and Photometric Imaging Receiver) instrument on the upcoming Herschel Space Observatory, in which Canadian scientists are also involved. Using the same detectors as SPIRE, BLAST has provided an invaluable first look at the sub-mm sky.
"The history of star formation in the universe is written out in our data. It is beautiful. And it is just a taste of things to come with SPIRE," said University of British Columbia Professor Mark Halpern. "The world-leading scientific success of Canadian graduate students and post-docs working on BLAST has been very impressive and, speaking as an educator, very gratifying."
Canadian partners in BLAST include the University of Toronto, the University of British Columbia, and AMEC Dynamic Structures Ltd. of Port Coquitlam, B.C. Canadian funding was provided by the Canadian Space Agency, the Natural Sciences and Engineering Research Council of Canada (NSERC), the Canada Foundation for Innovation, the Ontario Innovation Trust, and the University of Toronto.
International partners include the University of Pennsylvania, Brown University, the University of Miami, the Jet Propulsion Laboratory, Cardiff University, and the Instituto Nacional de Astrofisica of Mexico, with funding from NASA and the U.K.'s Particle Physics and Astronomy Research Council (PPARC).
For more information about this and other discoveries by BLAST, visit www.blastexperiment.info.
To read the scientific publications on BLAST's discovery, see: