Prime dust clouds ejected by a point source at three different times. The direction of the asteroid motion (apex) is shown relative to the direction toward the Sun. Each prime cloud contains 10⁵ dust particles. The cross section of particle number density (m⁻³) in the orbital plane of the source is shown 30 minutes (left) after ejection, 60 minutes (middle), and 90 minutes (right). The black dot indicates the position of the asteroid 90 minutes after the first prime cloud was ejected. All particles in the three prime clouds are of the same size corresponding to μ_R = 0.5GM_{S un}. The centers of these prime clouds lie on a syndyne.