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Vela Pulsar Glitch Caught 2004/07/07

A starquake on one of the littlest stars, 1500 light years away, caused some excitement among radio astronomers from South Africa and Australia.

The star "the Vela Pulsar" is no ordinary star. Compressed to the size of Johannesburg by a massive supernova explosion, it now drifts through space spinning eleven times a second and flashing like a cosmic emergency light. Pulsars are the next best thing to black holes, and Vela is an unusual adolescent version, not yet settled down into middle age, it suffers from rotational stresses that build up to cause the starquakes.

Sarah Buchner of the Hartebeesthoek Radio Astronomy Observatory near Krugersdorp, and Claire Flanagan of the Johannesburg Planetarium at the University of the Witwatersrand, have been watching Vela closely, hoping to catch a starquake. Richard Dodson uses a telescope in Hobart, Tasmania, to do the same. Yesterday, after a four-and-a-half year wait, it happened - Vela "glitched"! Both telescopes are watching the pulsar recover, hoping to learn something new about what's going on inside it.

For nearly thirty years, Vela was the most highly-stressed pulsar known. Recently, another twenty or so more "adolescents" have been discovered. All are in the southern skies. South Africa recently joined the international team to design the Square Kilometre Array, radio astronomers' dream telescope of the future. One reason for building an SKA is to study pulsars - gravitational monsters that help us understand our universe.

This was the formal announcement of the discovery:

PSR 0833-45

R. Dodson, Institute of Space and Astronautical Science; S. Buchner, Hartebeesthoek Radio Astronomy Observatory (HartRAO); B. Reid and D. Lewis, University of Tasmania; and C. Flanagan, Johannesburg Planetarium, report observing a sudden spin-up ("glitch") in the Vela pulsar (cf. IAUC 7347) on July 7.09 UT. Preliminary model fitting gives a fractional decrease of 2.1 x 10**-6 in the rotation period. The jump was first detected by the HartRAO 26-m telescope and observed at three frequencies (635.034, 990.25, and 1390.64 MHz) with the Mount Pleasant 14-m dish.