Feb 19, 2014 |
Rocks around the clock: asteroids pound tiny star
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(Nanowerk News) Scientists using CSIRO's Parkes telescope and another telescope in South Africa have found evidence that a tiny star called PSR J0738-4042 is being pounded by asteroids — large lumps of rock from space.
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"One of these rocks seems to have had a mass of about a billion tonnes," CSIRO astronomer and member of the research team Dr Ryan Shannon said.
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An artist's impression of an asteroid breaking up. (Image: NASA/JPL-Caltech)
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PSR J0738-4042 lies 37,000 light-years from Earth in the constellation of Puppis.
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The environment around this star is especially harsh, full of radiation and violent winds of particles.
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The star is a special one, a 'pulsar' that emits a beam of radio waves.
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"If a large rocky object can form here, planets could form around any star. That's exciting," Dr Shannon said.
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As the star spins, its radio beam flashes over Earth again and again with the regularity of a clock.
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In 2008 Dr Shannon and a colleague predicted how an infalling asteroid would affect a pulsar. It would, they said, alter the slowing of the pulsar's spin rate and the shape of the radio pulse that we see on Earth.
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"That is exactly what we see in this case," Dr Shannon said.
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"We think the pulsar's radio beam zaps the asteroid, vaporising it. But the vaporised particles are electrically charged and they slightly alter the process that creates the pulsar's beam."
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Asteroids around a pulsar could be created by the exploding star that formed the pulsar itself, the scientists say.
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The material blasted out from the explosion could fall back towards the forming pulsar, forming a disk of debris.
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Astronomers have found a dust disk around another pulsar called J0146+61.
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"This sort of dust disk could provide the 'seeds' that grow into larger asteroids," said Mr Paul Brook, a PhD student co-supervised by the University of Oxford and CSIRO who led the study of PSR J0738-4042.
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In 1992 two planet-sized objects were found around a pulsar called PSR 1257+12. But these were probably formed by a different mechanism, the astronomers say.
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The new study has been published as a paper in The Astrophysical Journal Letters ("Evidence of an asteroid encountering a pulsar"), a leading journal of astronomical research.
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