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First discovered by radio astronomers at Cambridge, pulsars make exceptional clocks, which enable a number of unique astronomical experiments. Some very old pulsars, which have been "spun up" to speeds of over 600 rotations per second by material flowing onto them from a companion star, appear to be rotating so smoothly that they may be even "keep time" more accurately than the best atomic clocks here on Earth.
``This star departs from being a perfect sphere by only 0.1 mm in 20 km. On Earth this would mean that no mountain could be higher than 3 cm!''
Astronomers know from other long-term observations, mostly done at Jodrell Bank, that a pulsar is made up largely of a neutron superfluid, with a solid crust. Current theories predict that the interaction between the superfluid and the crust should cause any precession to die out extremely quickly. ``But this pulsar is one hundred thousand years old, and it's still wobbling!'' exclaims Lyne. ``We really don't understand how this precession can be happening, and theorists are going to have to do some work to explain it,'' adds Stairs.
The trouble with that is that the debris associated with supernovae is nowhere to be seen in most of the discovered pulsars and astronomers don't even seem to notice this anomaly. It is entirely possible (and statistically more likely) that pulsars have nothing to do with the supernovae remnants in which they are seen. It's just that they were discovered there first, and assumed to be connected with supernovae, an assumption that continues despite evidence to the contrary.
Pulsars are rapidly rotating neutron stars emitting radio waves. They are the collapsed cores of supergiant stars that have been exploded as supernovae.
and there are other anomalous characteristics of pulsar signals. If millisecond pulsars are to fit in with the conventional model, they must be tiny to avoid the surface at the equator rotating at near lightspeed: PSR J1748-2446ad is the fastest known spinning pulsar, at 716 Hz, the period being 0.00139595482(6) seconds. According to Wikipedia it must be smaller than 32km in diameter. But we don't actually KNOW - it's just that it would fly apart if it were a rotating star that was any larger.
PSR B1931+24 "... appears as a normal pulsar for about a week and then 'switches off' for about one month before emitting pulses again. [..] this pulsar slows down more rapidly when the pulsar is on than when it is off. [.. the] breaking mechanism must be related to the radio emission and the processes creating it and the additional slow-down can be explained by a wind of particles leaving the pulsar's magnetosphere and carrying away rotational energy.