T. V. Shabanova

Properties of the linearly polarized radiation from PSR B0950+08

Measurements of average pulse profiles made with a single linear polarization over the range 41-112 MHz are presented for PSR B0950+08. We show that the observed variable structure of the pulse profiles is a result of Faraday sinusoidal modulation of the pulse intensity with frequency. The rotation measure corresponding to this effect, RM ≈ 4r ad m −2 , is about 3 times greater than the published value of RM = 1.35 rad m −2 (Taylor et al. 1993).

Pulsar Time Scale - PT

It is proposed to establish a new astronomical time scale - the pulsar time scale (PT). This scale is based on the very stable periodicity of the pulse sequence of a pulsar radio emission. The most stable pulsars such as PSR 0834+06, 0950+08, 1919+21 and the millisecond pulsar PSR 1937+214 are proposed as reference clocks for the new time scale. The pulsar time scale will keep both an interval and an epoch of the time and is more precise than existing UT and ET astronomical time scales.

Irregularity in the period of the pulsar B1822-09

The results of long-term monitoring of irregularies in the rotation rate of the pulsar B1822-09 (J1825-0935) are presented. Observations of the pulsar carried out since 1991 on the Large Phased Array of the Pushchino Radio Astronomy Observatory have revealed a new type of irregularity in the rotation, which has the form of “slow glitches” and is manifest as a gradual exponential growth in the rotation frequency of the star over several hundred days. In 1995–2004, five slow glitches in the rotation frequency were observed, with relative amplitudes of Δν/ν ∼ (2.5-32) × 10−9. Together with these unusual “slow glitches” in the rotation frequency, two modest ordinary glitches, associated with sudden, jump-like increases in the rotation frequency, were also observed. The observed irregularities in the rotation frequency of the pulsar are analyzed in detail, and possible interpretations of the results are discussed.

Pulsars as independent clocks with high long-term stability

In 1967, pulsars were discovered, which were later identified with rotating neutron stars, whose exisence had been predicted by Landau, Baade, and Twicky in the1930s. They are currently considered to form by gravitational collapse at a stage where material for thermonuclear processes is exhausted and the internal pressure cannot support the gravitational forces. Gravitational collapse causes a star having 1-3 solar masses to contract to a density of I017 kg/m ~, while the radius is reduced by comparison with the solar value by almost a factor l0 s and is about i0 km. The conservation of momentum means that the rotational speed increases in the proportion to the reduction in radius. The rotation periods for over 400 pulsars are from a few milliseconds to a few seconds. On current views, a rotation speed of over 1200 sec -I in a neutron star would disrupt it on account of centrifugal forces.

Pulsar time scale

In this article a new time scale is proposed, that of pulsar time PT which is based on the regular sequence of time intervals between pulses of a pulsars radio emissions. In discussing variations in the arrival times of pulsar radio emissions, three kinds of variations in the radiation periods are described. PSR 0834 + 06 is used as the basic reference pulsar. Time scales are also determined for reference pulsars PSR 0905 + 08 and 1919 + 21. The initial parameters for the three reference pulsars needed for managing a PT scale are presented. The basic PT scale is defined as the continuous sequence of time intervals between radio-emission pulses of the basic reference pulsar.