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The Balloon-Borne Large-Aperture Sub-millimetre Telescope (BLAST) was launched using a 33-storey tall balloon, and unlike other sub-millimetre telescopes, can generate colour images of starlight located billions of light years away.

Photo credit: UBC

Photo credit: UBC

Using a two-tonne telescope carried by a balloon the size of a 33-storey building, scientists from U of T and UBC have helped solve the mystery of the origins of starlight.

After two years spent analyzing data from the telescope BLAST (Balloon-borne Large-Aperture Sub-millimetre Telescope), physicists are releasing information about the birthplaces of ancient stars. The team of scientists from Canada, the U.S., and the U.K. recently revealed in Nature that half of the starlight in the universe comes from young, star-forming galaxies several billion light years away.

Dust usually conceals approximately half of a galaxy’s cosmic starlight and obscures its history of star formation. Flying the telescope above the atmosphere allowed the team to see deep into the universe, at wavelengths unattainable from ground level.

“Stars are born in clouds of gas and dust,” explains Barth Netterfield, a cosmologist in the Department of Astronomy and Astrophysics at U of T. “The dust absorbs the starlight, hiding the young stars from view. The brightest stars in the universe are also the shortest–lived, and many never leave their stellar nursery.”

BLAST’s thermo-detectors were able to identify the warmed dust, emitting light at far-infrared and submillimetre wavelengths invisible to the human eye, Netterfield explains.

“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,” says UBC professor Mark Halpern.

As UBC post-doctoral fellow Ed Chapin explains, the sub-millimetre telescopes used over the past decade could only create black-and-white pictures no bigger than the size of a fingernail. Today BLAST can easily produce hand-sized colour images, which marks a great advancement in the study of astronomy.

The data obtained from BLAST will help scientists better understand the history of the universe, and how it has changed over centuries. By providing them with a new outlook on the universe, BLAST will help scientists make new discoveries over a range of topics, like the formation of stars and the evolution of distant galaxies.

“In the distant universe, galaxies look very different,” explained Dr. Enzo Pascale, who led the U.K. team. “They’re much more massive, forming stars at a very high rate of thousands per year. If you look at our own Milky Way galaxy today, it forms perhaps just four stars a year.”

BLAST has also helped to answer pending decade-old questions. In the 1990s, NASA’s COBE satellite discovered the Far Infrared Background, a nearly uniform glow of submillimetre light. While scientists predicted that this radiation was coming from warmed dust-enshrouding young stars, the Far Infrared Background’s origins remained unsolved.

BLAST has finally unravelled this mystery, revealing that all of the Far Infrared Background comes from individual distant galaxies. BLAST can also examine star formation locally in the Milky Way, and the team is about to release the largest survey to date about the earliest stages of star formation, to be published in the Astrophysical Journal. The study proves the existence of a large population of cold clouds of gas and dust, which have cooled to less than minus 260 degrees Celsius. These cold cores are the birthplaces of stars.

In addition to leading the data analysis, the Canadian team that collaborated on BLAST also created most of the telescope’s hardware. The U of T team includes Barth Netterfield, department chair Peter G. Martin, and graduate students Marco P. Viero, Donald V. Wiebe (now a post-doctorate at UBC), and Enzo Pascale (now on faculty at Cardiff University).

This article was published on Jul 6, 2009 in The Varsity.

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