Pre-Main-Sequence Evolution Astrophysics Stellar Formation Pre-Main-Sequence Evolution Questions How do moving charges change the evolution of a magnetic field? What is a magnetic field? How were they formed? What causes magnetic fields to occur? What is a magnetic field composed of? How does a magnetic field act on matter through space? How can magnetic fields be created? How do protoplanetary discs form? What are protoplanetary bodies and what do they do? Why do some newly formed stars form protoplanetary discs while others do not? What are protoplanetary objects? How much mass was there in the protoplanetary disk out of which the planets formed, compared to the mass of the Sun? What physical process generates a force inside a pre-main-sequence star to offset the force of gravity and stop the star from slowly condensing and shrinking, thus producing a stable, non shrinking main-sequence star? Stellar Formation View all chapters Hydrostatic Equilibrium Free-Fall Times Pre-Main-Sequence Evolution Star Formation Theories Prev Next