Youngest known pulsar is behaving strangely

February 22nd, 2008 - 12:05 pm ICT by admin  

New York, Feb 22 (IANS) The youngest known pulsing neutron star - or pulsar - is behaving altogether like another type of star, a magnetar, forcing a rethink among astronomers. One kind of neutron star literally changes into another, and scientists studying this pulsing neutron called PSR J1846-0258 at NASA’s Goddard Space Flight Centre wonder whether they have stumbled on the long-sought missing link between different types of pulsars.

A neutron star forms when a big star explodes as a supernova, leaving behind an ultra-dense core. Most of these emit regular pulsations and are powered by rapid spins. So far, some 1,800 pulsars have been found in our galaxy.

Pulsars have very strong magnetic fields, but a few of them - slow rotators known as magnetars - derive their energy from even more powerful magnetic fields, the strongest known in the universe.

These fields can stress the neutron star’s solid crust past breaking point, triggering starquakes that snap magnetic-field lines, producing violent and sporadic X-ray bursts.

Astronomers have always wondered whether there is an evolutionary relationship between pulsars and magnetars - whether magnetars are a rare class of pulsars, or if some pulsars become magnetars during their life cycles.

Scientists studying archival records of the PSR J1846-0258 at NASA’s Rossi X-Ray Timing Explorer (RXTE) found four magnetar-like X-ray bursts in May and July 2006.

Lasting just a fraction of a second, each of them packed the power of at least 75,000 suns.

Previously, astronomers had classified PSR J1846 as a normal pulsar because of its fast spin (3.1 times per second) and pulsar-like spectrum, noted Fotis Gavriil of the Goddard Centre, lead author of a paper in the February issue of Sciencexpress.

Now there is a clear re-think on the subject.

“Never before has a regular pulsar been observed to produce magnetar bursts,” said Gavriil.

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