A sun and planetary system form from a gravitationally collapsing ball of gas and dust that flattens to form a spinning disk. The disk reaches an equilibrium size while the protosun continues to collapse in the center. [Source: Astro - U of Nebraska]
[Source Astro 001h PSU]
Temperature decreases with radial distance from the proto-sun [Source: Astrophysical & Planetary Sciences, University of Colorado]
Unformed planets circle the new born Sun, before its nuclear fires burst forth. (Courtesy of Helmut K. Wimmer, Hayden Planetarium, American Museum of Natural History.) (via NASA’s Cosmos)
A sun-like star as it might have looked at 1 million years of age, as minerals condense from the primordial gas cloud that will eventually form a sun and planets. Credit: NASA/JPL-Caltech/T. Pyle, SSC (via Phys.org)
A narrow asteroid belt filled with rocks and dusty debris orbits a star similar to our own Sun at 30 million years of age. [NASA/JPL-Caltech] (via Noble Gas Cosmochemistry Group)