Using the Australian Long Baseline Array, Miller-Jones et al. have conducted
Very Long Baseline Interferometry (VLBI) observations of
the pulsar/massive star binary system PSR B1259−63/LS 2883
4.4 years, fully sampling the 3.4-year orbital period.
The image above shows the observed orbital motion of PSR B1259−63, after subtracting
off the best-fitting proper motion and parallax signatures. The best-fitting
orbit is plotted as the solid line, with the colours denoting the pulsar’s
distance along the line of sight, in Astronomical Units (i.e., Earth-Sun distances), relative to the centre of mass of the
system. Yellow denotes when the pulsar is furthest away from the observer,
and black when it is closest. Blue squares show the predicted position at
each epoch. Red circles show the measured positions with 1σ error bars.
The centre of mass of the system is shown by the black star. The pulsar
moves clockwise around its orbit, as shown by the arrows.
From the measured parallax of 0.38 mas, a
distance of 2.6 kilo-parsecs is inferred,
and it is found that the
pulsar is moving clockwise around its orbit as viewed on the sky.
More details are given in
the paper published in
Monthly Notices of the Royal Astronomical Society.