According to astronomers led by Mr Paul Brook, a PhD student from the University of Oxford and CSIRO, a small pulsar dubbed PSR J0738-4042 is being pounded by giant asteroids.
This is an artist’s impression of an asteroid breaking up. Credit: NASA / JPL-Caltech.
PSR J0738-4042 is located in the constellation of Puppis, about 37,000 light-years away.
The environment around this pulsar 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,” said Dr Ryan Shannon of CSIRO Astronomy and Space Science, who is the senior author of a paper published in the Astrophysical Journal Letters (arXiv.org).
PSR J0738-4042 emits a beam of radio waves. As it spins, its radio beam flashes over Earth again and again with the regularity of a clock.
In 2008, the astronomers predicted how an infalling asteroid would affect a pulsar.
“It would 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.
“One of these rocks seems to have had a mass of about a billion tones.”
“We think the pulsar’s radio beam zaps the asteroid, vaporizing it. But the vaporized 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 material blasted out from the explosion could fall back towards the forming pulsar, forming a disk of debris.
The 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,” Mr Brook said.
“In 1992 two planet-sized objects were found around a pulsar called PSR 1257+12. But these were probably formed by a different mechanism.”
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P. R. Brook et al. 2014. Evidence of an Asteroid Encountering a Pulsar. ApJ 780, L31; doi: 10.1088/2041-8205/780/2/L31
