7.1 Astronomy
Stars
Orbits
Similar mass to sun
Larger mass than sun
The lifecycle of a star depends on the star's mass
Outward forces (radiation pressure) balanced by inward gravitational forces
Red Supergiant
Red Giant
Forces unbalanced as hydrogen runs out
Outward forces greater causing swelling
White Dwarf
Fusion stops and star contracts under gravity
Black Dwarf
Star's energy runs out
Protostar
Dust and gas pulled together by gravity
Larger main sequence stars swell to supergiants
Supernova
Large explosion
Heavy elements from core sent into the universe
Black Hole
Largest red supergiants contract resulting in a black hole
Neutron star
Formed by large mass red supergiants collapsing
Circular orbits
Stable orbits
Constant speed but changing velocity
In circular motion the direction is always changing
If orbital speed changes, the radius must change