Summary P8 Space Physics

P8 Space Physics
Life Cycle of Stars
 Nebula
 Cloud of dust and gas
 Protostar
 Force of gravity pulls the dust and gas together
 Temperature rises as it gets denser and more particles collide
 When temp gets high enough hydrogen, nuclei undergo nuclear fusion (P4)
 The core of the star is kept hot by this and it goes into main sequence
 Main sequence star
 Inward force due to gravity is balanced to the outward force due to pressure
 Higher temperature makes it expand
 Lower temp makes it shrink


 Red giant (our sun)
 When the hydrogen fuel is used up, outward force due to fusion is less than the inward
force due to gravity
 The star collapses inward and the temperature increases
 Helium nuclei fuse together to make heavier elements
 Star expands to create red giant
 White Dwarf
 Star stops fusing helium and shrinks
 Most of its outer atmosphere will be lost and a small, hot white dwarf will remain
 Black Dwarf
 Star becomes black dwarf when white dwarf cools down
 This doesn’t release any energy


 Super red giant (even bigger)
 Helium nuclei fuse together to produce even heavier elements (less heavy than iron)
 Supernova
 When red giant stops carrying out nuclear fusion there is a massive explosion
 The temperature of this is high enough to produce elements heavier than iron
 These elements are distributed throughout the universe
 Neutron star
 Neutrons densely packed together, hot
 Small (diameter of 20km), rapid spinning
 Black hole
 The force of gravity is so strong even light can’t escape