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Session 32 - Stars in Various Throes of Stellar Evolution.
Oral session, Monday, January 13
Piers 2/3,
We report on 2 and a half years of high precision timing observations of the bright millisecond pulsar PSR J0437-4715 made at Parkes radio observatory. The pulsar position is determined to extremely high precision, a few tens of micro-arcseconds, allowing a very precise determination of the pulsar proper motion and a significant measurement of the annual parallax. The parallax places the pulsar at a distance of about 180 parsecs. This independent distance measure enables us to calculate the kinematic contribution to the measured period derivative from which we estimate the pulsar timing age to be 11.6 Gyr. We also obtain a highly significant detection of a secular change in the projected semi-major axis of the binary due to the proper motion of the system. This places an upper limit on the orbital inclination of 40 degrees. Assuming the pulsar to be 1.4 solar mass, we obtain a lower limit of 0.2 solar masses on the companion. These results illustrate the wealth of information that can be extracted from precision timing and the usefulness of millisecond pulsars as stable clocks.
