Astronomers explore the Internet in search of 'stored-up' discoveries
25 October 2000ESA's ISO Archive celebrates its 1000th userCyberspace is increasingly breaking the frontiers of space and time... in the most universal sense. The Internet provides astronomers with quick short cuts to the most distant places in the Universe. Simply by allowing free access through the web to the images and data gathered by powerful telescopes, light that has travelled many thousand million years is now at your fingertips. A rapidly growing number of researchers are currently using this new resource, and in the process making valuable 'stored-up' discoveries. ESA's ISO (Infrared Space Observatory) Archive - one of the youngest of these astronomical databases - has recently celebrated the registration of 'user number 1000', who happens to be a young Spanish astronomer. He is convinced that "web-accessible databases are completely changing the way we do astronomy".
Last year, a team of French astronomers dug into the archive of ESA's Hipparcos satellite to look for a discovery that had been waiting there for years: a planet orbiting a distant star. The exoplanet dimmed the light from the star when passing in front of it, and Hipparcos, which operated until 1993, had registered these changes in the star's luminosity several times. But no one had noticed. Only when observations with other instruments drew attention to the old Hipparcos data was the 'shadow' found, much to the planet-hunters delight. Needless to say, astronomers are now searching the Hipparcos archive for more of the same.
Astronomers are starting to realise that many 'stored-up' discoveries are likely to be waiting in the astronomical archives. The archives are hence becoming a new powerful research tool, especially since they are freely, easily and quickly accessible through the Web. ESA has recently opened several archives and web-based services for astronomers, such as the IUE (International Ultraviolet Explorer) distributed archive, called INES; the ASTROVIRTEL project (in collaboration with ESO); and the ISO Archive, which stores the outcome of the most detailed exploration of the infrared Universe so far.
Last week the ISO Data Centre, in Villafranca, Spain, celebrated the registration of their 1000th user. ISO, the first true infrared observatory in space, operated until May 1998; its database, with nearly 30 000 scientific observations, opened in December 1998 and is now a reference point for astronomers from all areas, who want to check 'what the infrared has to say' about their favourite object or region. In less than two years the whole ISO Archive has been downloaded twice over by its subscribers.
'User number 1000' of the ISO archive is a surprised 27 year-old Nemesio Rodrmguez-Fernandez, from the Observatorio Astronomico Nacional, Spain, who will soon receive a gift from the ISO team. He is currently finishing his PhD thesis. He is trying to understand why some interstellar clouds in the centre of our Galaxy are much hotter, and over larger regions, than the clouds of the Galactic disk, and to do so he is studying emissions from the atoms and molecules which act as coolants. Since many of these chemical elements and compounds emit only at infrared wavelengths, which are absorbed by the Earth's atmosphere, an infrared space telescope is needed.
"They are doing a great job at the ISO Archive. It's not only easy to access; it's that the quality of the data is constantly improving thanks to new processing software they've developed", Rodrmguez-Fernandez says.
Archive Scientist Timo Prusti (ESA) is equally happy. "The community is taking good profit from our archive", he says. "The number of observations being retrieved has kept constant at around 3000 every month, which shows that astronomers from all over the world are finding good new reasons to use the ISO archive. I'm sure the trend will continue into the future. More unpredictable discoveries are probably hidden there".
Apart from the unexpected 'stored-up' discoveries, the archives make a new kind of research possible. For the first time in the history of astronomy huge samples of objects are easily available, which means, for instance, that it is now easier to differentiate between the exception and the rule. The quality of results is often based on the strength of statistics, which in turn depends on the size of the sample. And of course many interesting results can be achieved just by comparing many objects of the same kind.
Several groups are now working with the ISO Archive to find out how common black holes are in the centre of galaxies, or which stars are more likely to form planets. Another example is the study of large samples of similar stars in different stages of their lives, which will help to reconstruct in detail the processes by which an old star becomes a beautiful planetary nebula. "It's a completely new way to make astronomy", says 'user one thousand' of the ISO Archive.
NOTE FOR EDITORS:
The European Space Agency's infrared space observatory, ISO, operated from November 1995 to May 1998, almost a year longer than expected. An unprecedented observatory for infrared astronomy, able to examine cool and hidden places in the Universe, ISO made nearly 30 000 scientific observations.
Martin F. Kessler
(ISO Project Scientist):
Tel: +34 91 813 1254