AST-1002 Lecture 7: Star Formation and Planet Formation
Document Summary
Density of air 1. 42 x 1019 atoms/cm3. Density between starts depends on their distances. Dust blocks blue light more than red light (reddening) Massive young stars are always near molecular clouds. Less massive old stars are usually not near molecular clouds. Observing dusty clouds and massive stars using the black body spectrum. Spatial coincidence is consistent with the idea that stars are born in molecular clouds. Pressure keeps gas from collapsing, but sometimes gravity wins. Parcels of gas within a molecular cloud feel the gravitational attraction of all other parts of the molecular cloud-- leading to a net gravitational force towards the cloud"s center. If there is a balance between pressure and gravity, then there is a hydrostatic equilibrium. Some regions inside the cloud are more dense than others. Slightly denser regions collapse faster than their surroundings and become more pronounced. The collapsing cloud fragments into dense, star-forming cores.
