9 September, 1996. Copyright, 1996, Graphic News. All rights reserved

HIDDEN GALAXIES REVEALED
By Laura Spinney, Science Editor

EMBARGOED UNTIL 14.45 MONDAY 9 SEPTEMBER

LONDON, Graphic News, 10 September - Thousands of distant galaxies have been detected for the first time by the European Infrared Space Observatory, a British astrophysicist announced at the British AssociationÕs annual science meeting in Birmingham today.

The satellite observatory (ISO), which was launched last November by the European Space Agency, carries two cameras and two spectrometers that detect infrared radiation - energy wavelengths beyond the red end of the optical spectrum that are invisible to the human eye. Some galaxies radiate more than 99 per cent of their energy at these wavelengths, and one third of the energy emitted by our own Milky Way galaxy is in the infrared region. Although there are several ground-based infrared observatories around the world, they are unable to detect much of the infrared radiation from space because it is absorbed by the EarthÕs atmosphere. ISO is only the second satellite to have been sent into space that specifically detects infrared above the EarthÕs atmosphere.

Now Professor Michael Rowan-Robinson of Imperial College London and his colleagues are analysing the latest data from ISOÕs deep survey of a section of the sky. According to him, it reveals thousands of very faint infrared sources, the majority of which are galaxies about 300 million light years away. ÔThis is perhaps the first [ISO] data with potentially cosmological implications,Õ he says. The data also suggests that the first six galaxies found are Ôstarburst galaxiesÕ, which means up to half their gas may be forming into new stars.

The processing and interpretation of data from ISOÕs deep survey will not be complete for several months, says Rowan-Robinson. But he believes his team is on the brink of understanding how galaxies formed when the universe was at most a few billion years old.

Sources: British Association Annual Festival of Science, ÔThe New AstronomyÕ by Nigel Henbest and Michael Marten (2nd edition, published by Cambridge University Press, 1996)