The 1997 periastron passage of the binary pulsar PSR B1259−63 |
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| Authors: | S Johnston N Wex L Nicastro RN Manchester AG Lyne |
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| Institution: | 1Research Centre for Theoretical Astrophysics, University of Sydney, NSW 2006, Australia;2Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany;3Istituto di Fisica Cosmica con Applicazioni all'Informatica, CNR, Via U. La Malfa 153, I-90146 Palermo, Italy;4Australia Telescope National Facility, CSIRO, PO Box 76, Epping, NSW 2121, Australia;5University of Manchester, Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL |
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| Abstract: | We report here on multifrequency radio observations of the pulsed emission from PSR B1259?63 around the time of the closest approach (periastron) to its B2e companion star. There was a general increase in the dispersion measure (DM) and scatter-broadening of the pulsar, and a decrease in the flux density towards periastron although fluctuation in these parameters were seen on time-scales as short as minutes. The pulsed emission disappeared 16 d prior to periastron and remained undetectable until 16 d after periastron.
The observations are used to determine the parameters of the wind from the Be star. We show that a simple model, in which the wind density varies with radius as r ?2, provides a good fit to the data. The wind is highly turbulent with an outer scale of ≤1010 cm and an inner scale perhaps as small as 104 cm, a mean density of ～106 cm?3 and a velocity of ～2000 km s?1 at a distance of ～50 stellar radii. We find a correlation between DM variations and the pulse scattering times, suggesting that the same electrons are responsible for both effects. |
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| Keywords: | pulsars: individual: PSR B1259?63 |
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