The Physics of Protoplanetesimal Dust Agglomerates. II. Low-Velocity Collision Properties

摘要: For the investigation of collisions among protoplanetesimal dust aggregates, we performed microgravity experiments in which impacts high-porosity millimeter-sized aggregates into 2.5 cm can be studied. The consisted either monodisperse spherical, quasi-monodisperse irregular, or polydisperse irregular micrometer-sized grains and were produced by random ballistic deposition with porosities between 85% 93%. Impact velocities ranged from ~0.1 to ~3 m s−1, impact angles almost randomly distributed. In addition smooth surfaces target formed our experiments, "molded" such that radii local surface curvatures corresponded projectile radii, decreasing targets' 80%-85%. showed highest porosity targets always led sticking, whereas for less porous consisting spherical grains, intermediate high resulted bouncing a mass transfer aggregate. Sticking probabilities considerably decreased. targets, measured depth intrusion crater volume, able derive some interesting dynamical properties help collision model aggregates. Future models aggregate growth protoplanetary disks should take account noncentral impacts, compression, influence radius curvature on collisional outcome, possible agglomerates nonsticking collisions.