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