Infrared telescope opens new vistas to space scientists

IRAS, the Infrared (heat radiation) Astronomy Satellite, has given astronomers what may be their first direct look at another solar system. It's a ring around the star Vega containing objects that may range in size from pebbles to planets.

This is only the latest surprise that the international orbiting telescope has given astronomers. Since it was launched Jan. 25, it has found a number of cases of star birth. It has discovered new comets, including the comet IRAS-Araki-Alcock, which suddenly appeared close to Earth in late April. And earlier this summer, it observed a 20 million-mile tail on the comet Temple 2 - a well-known comet previously thought to be tailless.

In short, the IRAS project - a joint effort of Britain, the Netherlands, and the United States - is proving the astronomical truism that when a new ''window'' is opened on the universe, discoveries are likely to pour in. In this case, the window is the band of infrared wavelengths - wavelengths longer than those of visible light but shorter than those of radio waves - which are largely absorbed by Earth's atmosphere and are hard to observe from the ground. IRAS, working at wavelengths between 8 and 120 micrometers (millionths of a meter), has a clear view.

The new-found planetary system illustrates this. It is part of the cold, nonluminous matter of the universe. Such material, with temperatures somewhere between absolute zero and a few degrees Fahrenheit, gives off little or no light. Yet it is likely to be as important cosmically as is the hotter, luminous material of the stars. The Vega ring, with a temperature some 300 degrees below zero F., shines brightly in the IRAS infrared data.

These data are gathered for the project at Britain's Rutherford Appleton Laboratory. US astronomers Hartmut H. Aumann of the National Aeronautics and Space Administration's Jet Propulsion Laboratory and Fred Gillett of the Kitt Peak National Observatory were using data on the star Vega as a means of calibrating the IRAS telescope when they found the planetary ring.

Its IR (infrared) radiation comes from an extended region some 80 astronomical units (about 7.4 billion miles) out from the star. Drs. Aumann and Gillett say this suggests a cloud of debris similar to that from which our own planetary system is thought to have formed. The Vega system would be in a younger state than our planets since the age of the star itself is less than a billion years compared with 4.6 billion for the sun.

While this first direct observation of another planetary system is an important discovery, it is only a small part of the IRAS workload. The telescope is systematically mapping the sky at IR wavelengths. Before the nominal end of its mission next January, it is expected to have identified some 15,000 asteroids or more, several times the number known so far. It also is scanning deep space to survey both near and distant galaxies. Again, new discoveries are likely, such as the ring of dust IRAS has already found around the Andromeda galaxy.

With data coming in at a rate roughly equivalent to 10 million English words a day, the IRAS team can take only a cursory look at them now. Many more discoveries likely await the scientists as they make more extensive analyses in the years ahead.

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