An observing program dedicated to a search for extrasolar planets around 50 nearby/bright binary stars will be carried out. Key here is the use of the Palomar Testbed Interferometer, which is the only dual beam optical interferometer in existence. Using the nearby companion in each binary as a reference, astrometric precision of 10-20 micro-arcseconds will be possible (almost 100 times better than is possible with a single dish optical system). Saturn-Jupiter mass planets with periods of a few years will therefore be detectable (possibly even Uranus-Neptune mass if 10 micro-arcseconds can be reached over long periods). Such a search of close binaries would be extremely difficult using traditional spectroscopic techniques and any planets found here will be of great value in constraining planet formation theories. A secondary outcome of this work is improved (by factors of 10-100) orbits of dozens of close binaries from the target list, which when combined with radial velocities will lead to higher precision masses. A graduate student will be supported and be trained in interferometric techniques. This is a rapidly growing field and a significant demand for expertise is expected in the future.
