DUST DEPLETION IN THE INNER DISK OF BETA-PICTORIS AS A POSSIBLE INDICATOR OF PLANETS

IT is not yet possible to see planets orbiting other stars, although this may soon change as observing methods improve(1). Indirect evidence for the presence of circumstellar dust disks out of which planets could form has been obtained for several stars, in the form of excess infrared emission, presumed to be from the hot dust(2,3). Planets orbiting in such dust disks would be expected to sweep out dust-free tracks(4). Indirect evidence for dust-free regions has been reported(5-9), based on an analysis of the spectral energy distribution, but the interpretation of the observation is not unique(7,9). Here we present an infrared image of the inner dust disk of the star beta Pictoris with a linear resolution of 5 astronomical units (AU), equivalent to the distance from the Sun to Jupiter. We find that the dust is asymmetrically distributed and is clearly depleted within 40 AU Of the star, which we interpret as indicating the possible presence of at least one planetary body orbiting beta Pictoris.