Pulsar's companion: a question of age.
Binary pulsars, systems in which pulsars orbit around companion stars, permit astrophysicists to gain important information about the nature and evolution of pulsars, which are believed to be neutron stars. In the Nov. 13 NATURE, Gregory A. Wright and Edwin D. Loh of Princeton (N.J.) University report that they have found the companion of the binary pulsar PSR1855+09, one of the "millisecond pulsars" with a pulse period of 5.3621004525 milliseconds.
The companion is a white dwarf star with a temperature of 5,900[deg.]K. that temperature implies that the pulsar is more than 2 billion years old. However, according to the "naive" theory, the pulsar's magnetic field, which poers its pulsations, should have decayed away to nothing after about 10 million years, and this pulsar ought no longer to be active.
A possible way out is a suggestion of Shrinivas R. Kulkarni of Caltech in Pasadena that pulsar fields have two components, one that decays and one that remains constant. The field of this pulsar is 340 million gauss, and that, Wright and Loh remark, could be a measure of the strength of the constant component of pulsar fields.
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|Title Annotation:||binary pulsar and white dwarf star|
|Date:||Nov 29, 1986|
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