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Stellar lighthouse devours asteroid?

The pulsar PSR J0738-4042 might have encountered an asteroid that's thrown off its ultra-precise ticking.

A pulsar's beat relies on powerful magnetic fields that send jets of particles streaming out from its magnetic poles at relativistic speeds. As the pulsar spins, this beam appears to flash at us, usually with astounding regularity.

Paul Brook (Oxford University, UK) and colleagues analyzed fluctuations in PSR J0738-4042's pulse pattern using observations taken with the Hartebeesthoek Radio Astronomy Observatory in South Africa and the Parkes radio telescope in Australia from 1988 to 2012. In September 2005, the pulsar abruptly hiccupped, leading to a reduced spindown rate.

The glitch corresponds to what's expected from a mass influx of about 1 trillion kg (1 billion tons), consistent with asteroid masses. We could be witnessing a close encounter with an asteroid or infalling debris, the team argues in the January 10th Astrophysical Journal Letters.

Debris disks should form around some pulsars from material that falls back toward the stellar corpse after the supernova. Should an asteroid-size piece from the disk embark on a collision course, the pulsar's intense radiation would vaporize the rock before it came too close. But the dismembered asteroid's charged particles would then flow into the pulsar's magnetic field and alter its currents. Since the magnetic field powers the beam of particles, incoming asteroid guts would throw off the pulsar's clock. Still, an asteroid is only one of many possible solutions.

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Title Annotation:PULSAR
Author:Poore, Emily
Publication:Sky & Telescope
Article Type:Brief article
Geographic Code:1USA
Date:Jun 1, 2014
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