PERTURBATIONS OF A PLANET ON THE BETA-PICTORIS CIRCUMSTELLAR DUST DISK .3. TIME-SCALE OF COLLISIONAL DESTRUCTION VERSUS RESONANCE TIME-SCALE

We have already shown that a planet orbiting beta Pictoris is able to confine the circumstellar dust. Here we present new numerical simulati ons which improve this model. The new model takes into account destruc tive collisions between particles, and looks at the steady state betwe en the collision and the dust replenishment. We show that there exists a critical value of the normal optical depth (tau(opc) similar to 4 x 10(-4)) and if the optical depth is smaller than this critical value in the resonant region (20-50 AU), asymmetric structures are created b y the planet and maintained in spite of collisions. Although these str uctures cannot explain the asymmetries now observed in the disk, they could be a way to reveal bodies otherwise invisible by direct imagery. (C) 1996 Academic Press, Inc.