An upper limit on the reflected light from the planet orbiting the star tau Bootis

The planet orbiting tau Boo at a separation of 0.046 AU could produce a ref lected light flux as bright as 1 x 10(-4) relative to that of the star. A s pectrum of the system will contain a reflected light component which varies in amplitude and Doppler shift as the planet orbits the star. Assuming the secondary spectrum is primarily the reflected stellar spectrum, we can lim it the relative reflected light flux to be less than 5 x 10(-5). This impli es an upper limit of 0.3 for the planetary geometric albedo near 480 nm, as suming a planetary radius of 1.2 R-Jup. This albedo is significantly less t han that of any of the giant planets of the solar system and is not consist ent with certain published theoretical predictions.