Revved-up antics of a pulsar jet

Whipping around like an out-of-control fire hose, a mammoth jet of charged particles gushing from a collapsed star is varying its shape and brightness more rapidly than any other known jet in the heavens.

GUSHER. X-ray images taken in November 2000 (top) and April 2002 show the rapid variation in a jet of particles (top right in each image) associated with the Vela pulsar (lower left in the images). NASA, CXC, and G. Pavlov et al./Penn. State

The jet, a half light-year in length, is spewing electrons and positrons from the Vela pulsar, a rapidly rotating neutron star a mere 20 kilometers in diameter. A time-lapse movie made using images from the Chandra X-ray Observatory shows that the outer half of the jet bends and flails. In mere weeks, the jet, which contains bright blobs flying out at half the sped of light, varies from being straight to hook-shaped.

Confined by strong magnetic fields, the X-ray–emitting particles in the Vela jet are accelerated by voltages 100 million times that of a lightning bolt, says Marcus A. Teter of Pennsylvania State University in State College. That potential is created by the rapid rotation of the pulsar, as well as the star’s intense magnetic field.

The jet’s variability may be caused by headwinds created as the pulsar plows through space at 300,000 kilometers per hour. The blobs may mark where increased magnetic fields and particle pressure have caused kinks in the jet’s flow.

Studying the antics of the Vela jet may shed light on jets spewed by supermassive black holes, which can take millions of years to vary significantly, says Teeter.

He and his Penn State colleagues describe their study in the July 10 Astrophysical Journal.


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