As you may now I spend most of my time analysing data from the star tracker on the WIRE satellite. This is the latest discovery with WIRE:

In June 2004 I discovered that the bright southern star Psi Centauri was a new eclipsing binary star. The period of the two orbiting stars was 38.8 days. You may read the scientific paper for more details.

Just a few months ago WIRE observed Psi Cen again at the time when we predicted that the primary eclipse would occur again. In the picture below you can see the data from 2004 (blue points) and 2006 (yellow points). The eclipse occurs when the faintest of the two stars passes in front of the brightest star thus blocking out about 30% of the total light. The slight offset in time (or phase) between the two light curves is there because we have a small uncertainty on the period of the system of about 50 seconds (relative to the 38.8 day period that's not a lot). With the new data we can improve the period to within just 3 seconds.

More interestingly we have just received some new spectroscopic data. This will enable us to measure the movement of the two stars relative to each other. From this we can determine the absolute masses and radii of the stars with very high accuracy - perhaps as good as half a percent. This result will put constrains on the theoretical models of the two late B / early A-type stars (around B9 and A2) that make up the Psi Cen binary system.

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