Stellar particle distribution of the face-on disk from model 371 within 40 kpc for snapshot 680 (left) and 1200 (right). The color of the image is based on assuming each newborn stellar particle evolves as a simple stellar population and has been observed with the filters of u, g, and z of the Sloan Digital Sky Survey. For example, the blue colors in the images indicate a stellar age of about 100 Myr.