Submillimeter studies of dusty debris around nearby stars

Imaging of remnant disks of dusty debris around main-sequence stars gives valuable clues to the planetary formation process. Submillimeter observations of such disks are relatively new, but with technological advances we now have the capability to directly image the dust distributions, with negligible signal from the star itself. This review discusses recent results for the nearby stars whose disks were first detected in the far-infrared by IRAS-in particular, the "Big Four" prototypes: Vega, Fomalhaut, beta Pic, and epsilon Eri. The disks appear very diverse, and some surprising features were uncovered, including dominance of grains of particular sizes, and clumping within disks that may trace perturbations by planets. Generally, the amounts of dust detected are very small (of the order of the mass of the Moon), and the grains need to be continually replenished, for example from collisions of larger bodies. The decline of dust mass with stellar age allows us to establish a rough timescale of less than or similar to 10 Myr for the formation of rocky planets and the solid cores of gas giants. Finally, we discuss future submillimeter observations that will reveal the diversity of disks around far more nearby stars, and probe scales as small as a few AU.