Stars born in cosmic frenzy

The violent labour pains that accompany star birth have been revealed by a supercomputer study, writes Steve Farrar.

In a cosmic feeding frenzy, nascent stars appear to battle with each other to scoop up interstellar gas. They tear matter from one another and expel the runts of the litter from a crowded nursery to fizzle out as brown dwarfs.

The chaotic processes have emerged from one of the most complex supercomputer simulations of star formation attempted.

The collapse of a small interstellar cloud of gas was recreated at the UK Astrophysical Fluid Facility, a national facility based at Leicester University. The work was done by Matthew Bate, lecturer in astrophysics at Exeter University, with colleagues Ian Bonnell of St Andrews University and Volker Bromm of the Harvard-Smithsonian Center for Astrophysics, in the United States.

The project involved tracking the interaction of 3.5 million elements of gas that formed 50 stars and brown dwarfs over 0,000 years.

The calculations were so complex that they required 100,000 hours to run - about 10 per cent of the available time in the supercomputer's first full year.

The findings, revealed at the UK National Astronomy Meeting today and to be published in the Monthly Notices of the Royal Astronomical Society , have shown a highly dynamic scene previously only speculated about.

About half of the objects were ejected from the group before they had had enough time to gather sufficient gas to start fusing hydrogen and become fully fledged stars. This preponderance of brown dwarfs corresponds with recent astronomical surveys.

The simulation also found that many newborn stars strip material from the planet-forming discs of dust that collect around their neighbours.

Three-quarters of the stars were left with truncated discs, suggesting that only a few would preserve enough matter to later form a planetary system like our own.

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Contact steve.farrar@thes.co.uk