https://en.wikipedia.org/wiki/Nebular_hypothesis
The nebular hypothesis is the idea that a spinning cloud of dust made of mostly light elements, called a nebula, flattened into a protoplanetary disk, and became a solar system consisting of a star with orbiting planets.
Originally applied to the Solar System, the process of planetary system formation is now thought to be at work throughout the universe.
Protoplanetary disk (原行星盤)
A protoplanetary disk is a rotating circumstellar disk of dense gas surrounding a young newly formed star, i.e. a TTS. If the disk is massive enough, the runaway accretions begin resulting in the rapid—100,000–300,000 years—formation of Moon- to Mars-sized planetary embryos.
T Tauri stars (TTS) (金牛T星)
T Tauri stars (TTS) are a class of variable stars that are less than about ten million years old.[1] This class is named after the prototype, T Tauri, a young star in the Taurus star-forming region.
