Free core nutation and Chandler wobble of pulsar
Abstract
In 2000 year Stairs, Lyne and Shemar reported the discovery of the long-term, highly periodic and correlated variations pulse shape and of the rate of slow-down of the pulsar PSR B1828-11 with period variations approximately 1000, 500 and 250 days. According to Stairs et al. (2000), probably, the precession of the spin axis is caused by asymmetry in the shape of the pulsar. It is known that rotation of the terrestrial planets having rigid mantle and elliptical liquid core is characterized by Free Core Nutation (FCN). Therewith any celestial body whose rotation axis does not coincide with the main inertia axis is characterized by Chandler Wobble (CW). These phenomena of FCN and CW are manifested as periodical oscillations of rotation axis of the planet in inertial reference system. For rotating pulsar we deal with the case of modulation of pulses emitted around the direction of the magnetic axis of a pulsar whose symmetry axis does not coincide with the angular velocity vector. We have obtained the periods of PC W and PF C N for different pulsars, correctly extending for neutron star the theory of core-mantle differential rotation of the planets (Petrova &Gusev, 2001). It was made in the frame of Hamiltonian approach for description of rotation of two-layer pulsar having rigid crust and liquid mantle.
- Publication:
-
34th COSPAR Scientific Assembly
- Pub Date:
- 2002
- Bibcode:
- 2002cosp...34E1352K