millisecond pulsars

millisecond pulsars

A class of pulsars that produce pulses with a period of only a few milliseconds, and are thus neutron stars rotating hundreds of times per second. Unlike the fast ‘normal’ pulsars (e.g. the Crab and Vela pulsars), the millisecond pulsars' fast rotation is not a result of youth; they have almost certainly been ‘spun up’ by mass transfer in a close binary star at an earlier evolutionary stage. Rapid rotation of a neutron star is normally slowed precipitously because the star's strong magnetic field radiates away the rotational energy, as with the Crab pulsar (see Crab nebula); the millisecond pulsars detected so far, however, have only a very gradual rate of slowing down, probably because their magnetic fields are comparatively weak (104–105 tesla).

PSR 1937+21 was the first millisecond pulsar to be found, 1982, and is currently the fastest known (period 1.56 ms, i.e. 642 rotations per second). The second to be found, PSR 1953+29 (6.1 ms), is a member of a binary pulsar system; it orbits its unseen companion in 120 days. The old but rapidly spinning binary pulsar PSR 1913+16 also belongs in this class, although its period is rather longer (59 ms).

Recent surveys have discovered large numbers of millisecond pulsars in globular clusters; more than half are close binary pulsars. It is generally believed that most of the single millisecond pulsars were initially members of binary systems, but lost their companion stars either because of a stellar collision (which is possible in globular clusters) or because the radiation emitted by the pulsars completely destroyed, or ‘evaporated’, the companion stars (see black-widow pulsars). One millisecond pulsar (PSR 1257+12) appears to be orbited by two planet-mass objects (see planet pulsar).

References in periodicals archive ?
The new study is the work of researchers from the Australian National University (ANU), who had a working hypothesis 6 the signal came from millisecond pulsars, which are thousands of rapidly spinning neutron stars.
The idea is to use the millisecond pulsars that exist throughout our galaxy like GPS satellite clocks, pinpointing the pulsations' arrival times to determine one's position anywhere in the solar system.
But some, called millisecond pulsars, rotate hundreds of times faster.
Golshan, "Minimum uncertainties in position and velocity determination using x-ray photons from millisecond pulsars," in Proceedings of the ION NTM Conference, pp.
A population of gamma-ray millisecond pulsars seen with the Fermi Large Area Telescope.
While young pulsars usually appear in isolation, more than half of millisecond pulsars occur in binary systems, which suggested an explanation for their rapid spin.
Their study can also help explain an increasing number of observed binary millisecond pulsars which seem to require a triple system origin.
Prof Lyne then considered the creation of binary pulsar systems and millisecond pulsars, objects rotating so rapidly that the pulse of radiation from the star occurs hundreds of times a second.
To detect a general background of such waves, astronomers would need to monitor 20 of the millisecond pulsars for five to 10 years, with the arrival time of the radio waves determined to an accuracy of 100 nanoseconds, Jenet estimates.
Other such millisecond pulsars (those that turn in the range of a thousandth of a second) have been discovered since.
Extensive monitoring of dozens of millisecond pulsars, for instance, relies heavily on the Arecibo dish's large size.
Such objects, called transitional millisecond pulsars, have been observed but some of their properties don't match up with X9.