Formation of the Sun
- The interstellar medium, out of which the sun formed, is primarily gaseous
- If gas is concentrated, Gravity (inward) force will overwhelm the thermal pressure (outward) force, leading to collapse
- complex process, from
- molecular clouds, ~20,000 AU in size
- to sun, a tiny 0.01 AU across
Gas can’t collapse directly to a sphere
- molecular cloud is rotating vu-graph
- rotation means angular momentum, which must be conserved
- collapse parallel to axis is no problem
- collapse perpendicular to the axis is a problem
- must speed up to conserve angular momentum
- Kepler’s second law
- ice skater as she pulls in her arms