European Southern Observatory gets first glimpse of young 'heavy stars'

Brussels, 17 Jun 2003

The European Southern Observatory (ESO) has obtained unprecedented images of the very first stages in the formation of heavy stars.

The observations were successfully conducted using a powerful arsenal of state-of-the-art instruments working at different wavelengths, from the infrared to the millimetre spectral region. However, it was the cloud ripping effect of strong stellar winds from adjacent hot stars that finally permitted the ESO team of astronomers to glimpse several bona-fide massive heavy stars, only 100,000 years old and still growing.

Heavy stars are high mass stellar formations located many thousands of light-years further way than low mass stars like the Sun. Up until now, due to their distance, details of the heavy stars' formation have remained a mystery. Heavy stars have also been difficult to observe in the early stages of their formation, as they tend to evolve much faster than low mass stars and are very deeply embedded in their natal clouds of dust and gas.

Commenting on the sighting of the heavy stars, collectively known as IRS 9A-C, ESO astronomer Dieter Nürnberger said: 'We now have convincing arguments to consider IRS 9A-C as a kind of Rosetta Stone for our understanding of the earliest phases of the formation of massive stars. I know of no other high-mass protostellar candidates which have been revealed at such an early evolutionary stage - we must be grateful for the curtain-lifting stellar winds in that area! The new near- and mid-infrared observations are giving us a first look into this extremely interesting phase of stellar evolution.'

There has been much debate over the formation of heavy stars: Some astronomers believe that they were formed following the fusion or accretion of large amounts of circumstellar material, whereas others support the theory that heavy stars are the result of a collision by protostars of intermediate masses. According to Mr Nürnberger, the new observations suggest that a collision hypothesis is now more likely.

For further information, please consult the following web address:
http://www.eso.org/outreach/press-rel/pr -2003/pr-15-03.html

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