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THE Hubble Space Telescope has spotted dust coalescing in discs around stars in Orion. Astronomers say they may be witnessing the birth of new planets.
Larry Esposito, an astronomer at the University of Colorado in Boulder, his graduate student Henry Throop and their colleagues looked at dust discs against the bright background of the Orion nebula. Using an infrared camera on the Hubble Space Telescope, they showed that the rings around three stars contain dust at least 10 micrometres across. This is nearly 100 times the size of interstellar dust in the region.
The observations reveal a critical early stage in planetary evolution. Stars form when interstellar dust clouds collapse. Some of the debris remains in orbit around the forming stars, and theory suggests that the dust grains, which start off about 0á2 micrometres wide, should aggregate into millimetre-wide particles within 10 000 years. Over tens of millions of years these can stick together to form planets.
Throop, who announced the results last week at a meeting of the American Astronomical Society's Division for Planetary Sciences in Madison, Wisconsin, says planets may well be forming in the Orion nebula. As many as 30 per cent of the young stars there appear to have discs. "It suggests planet formation may be relatively common," says Throop.
This week, Helen Walker of the Rutherford Appleton Laboratory in Oxfordshire reported that data from the Infrared Space Observatory have revealed even larger particles, 200 micrometres across, around the star Vega.
Author: Jeff Hecht
New Scientist magazine, issue 24th October.
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