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 ?
Transitional millisecond pulsars provide us with a unique laboratory to study the interaction between the matter inflowing towards the NS, its rotating magnetosphere and the outgoing radiation, particle wind and jets.
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.
Researchers regard the system as a unique laboratory for understanding how millisecond pulsars form and for studying details of how accretion takes place on neutron stars.
These systems can completely consume their companion stars, and that's how we think solitary millisecond pulsars form", said Alice Harding, an astrophysicist at NASA's Goddard Space Flight Center said in a statement.
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.
Because of their predictable pulsations-especially millisecond pulsars, which are the mission's prime target and are found to spin as much as 700 times per second-"they are extremely reliable celestial clocks" and can provide high-precision timing just like the atomic clock signals supplied through the 26-satellite, military-operated Global Positioning System (GPS), an Earth-centric service that weakens the farther one travels out beyond Earth orbit and into the solar system, Arzoumanian said.
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.
There are some excess gamma rays observed in the Galactic Center but these are probably due to an unresolved population of millisecond pulsars.
17 ( ANI ): Two astronomers have proposed a new path for the formation of a newly discovered class of millisecond pulsars with similar orbital periods and eccentricities.
This star's capricious behavior appears to be fueled by a nearby companion star and may give new insights into the birth of millisecond pulsars.