Credit: NASA/JPL-Caltech
As the star spins, its radio beam flashes over Earth again and again with the regularity of a clock.
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.
"That is exactly what we see in this case," Dr Shannon said.
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.
"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.
PSR J0738-4042 lies 37,000 light-years from Earth in the constellation of Puppis.
The environment around this star is especially harsh, full of radiation and violent winds of particles.
"If a large rocky object can form here, planets could form around any star. That's exciting," Dr Shannon said.
The star is a special one, a 'pulsar' that emits a beam of radio waves.
As the star spins, its radio beam flashes over Earth again and again with the regularity of a clock.
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.
"That is exactly what we see in this case," Dr Shannon said.
"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."
Asteroids around a pulsar could be created by the exploding star that formed the pulsar itself, the scientists say.
The material blasted out from the explosion could fall back towards the forming pulsar, forming a disk of debris.
Astronomers have found a dust disk around another pulsar called J0146+61.
"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.
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.
The new study has been published as a paper in The Astrophysical Journal Letters, a leading journal of astronomical research: Evidence of an asteroid encountering a pulsar [external link].
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Contact Information
Ms Helen Sim
Media and Public Relations
Astronomy and Space Science
Phone: +61 2 9372 4251
Alt Phone: +61 419 635 905
Email: Helen.Sim@csiro.au
Dr Ryan Shannon
Postdoctoral Fellow
Astronomy and Space Science
Phone: +61 2 9372 4326
Alt Phone: +61 403 692 028
Email: Ryan.Shannon@csiro.au
Source: CSIRO
