Artist concept of IRAS

The first images of infrared sources produced from data radioed to Earth by the Infrared Astronomical Satellite (IRAS), launched Jan. 25 by NASA, revealed sources in the Large Magellanic Cloud (LMC) not visible to optical telescopes on Earth.

The highly sensitive telescope scanned part of the LMC recording infrared emissions from stars and clouds of dust and gas. The LMC is l55,000 light years from Earth and is the closest galaxy.

In nebula of gas and dust within the LMC called 30 Doradus, IRAS produced an image of cloud nicknamed the Tarantula by astronomers as the long, separated filaments of the cloud gave it spider-like appearance. The image is presented in false-color with white being the brightest detector reading and blue the faintest.

The Tarantula is in portion of an IRAS scan across the Large Magellanic Cloud in which dozens of infrared sources, stars and regions of dust and gas, are seen, most of which are not visible from Earth by optical telescopes. Some of the sources may be new stars forming behind clouds of dust and gas that radiate the star's energy in the infrared.

The 30 Doradus nebula is giant II region in the Large Magellanic Cloud. II regions are clouds of hydrogen that have been ionized by the ultraviolet radiation from very hot star. Giant II regions such as 30 Doradus are powerful emitters of far infrared radiation. This image represents the infrared signal at wavelength of l00 microns, and shows the complicated structure present in this nebula.

Some astronomers have suggested that this nebula contains monster star, thousands of times more massive than the Sun.

IRAS is joint international mission linking the United States, The Netherlands and the United Kingdom.

The United States produced the ultra-sensitive telescope, the Netherlands provided the basic spacecraft to carry the telescope and the United Kingdom operates the IRAS tracking station at the Rutherford Appleton Laboratory at Chilton.

The telescope's sensitivity is produced by the use of liquid helium in the satellite to cool the infrared detectors to 2 degrees above absolute zero. This allows them to register the faintest impulse of infrared from objects in space.

IRAS will scan the universe for period of 7 to 9 months to produce an all-sky IR survey for the first time and is expected to revolutionize astronomical knowledge.

Infrared observations from Earth are limited as the atmosphere blocks almost all frequencies of infrared.

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