Astrophysics

• Blue Shift


  If an object is moving towards you, the wave becomes high frequency
• Red Shift


  If an object is moving away, the wave becomes low frequency
• If everything is flying away from you, the gravity is stretched
• The universe started at one point
• The universe is expanding
• The universe started 13.5 billion years ago (singularity point)
• The Big Bang Theory

  The Galaxies stay the same size, but are moving further apart
• Evidence for the Big Bang Theory

  • Cosmic Microwave Background (CMB)
• Hubble's Law


  The recession speed of galaxies moving away from Earth is proportional to their distance
• The further away a galaxy, the faster its recession velocity
• The gradient of a graph of recession speed against distance is equal to the Hubble constant
• Exoplanets


  Planets outside our solar system
• Doppler Effect


  In the EM spectrum, there's a high frequency light (violet) and low frequency light (red)
• If the object emitting light is moving away or towards you


  The light can be shifted into other colours
• If a star is emitting light but not moving, the light looks the same in all directions
• If a star is moving while emitting light

  The light goes bluer (move towards), redder (move away)
• Giant star


  larger and brighter than a normal star
• Red Supergiant


  Big giant stars with lower surface temperature
• Supernova


  A dying star that explodes violently, producing an extremely bright object that can last for months
• Blackhole


  Created when a giant star undergoes a supernova, with a density/gravity so dense that not even light can escape
• Neutron Star


  An object with mass not large enough to form a blackhole, instead forming a star made entirely of neutrons
• Orbital Period


  The time it takes for an object to complete a single orbit
• Galaxy


  A cluster of stars held together by the force of gravity
• Types of Galaxies


  • Elliptical
  • Spiral
  • Barred Spiral
  • Lenticular
  • Irregular
• Life Cycle of a Star

  1. Protostar

  2. Main Sequence

  3. Red Giant

  4. White Dwarf

  5. Black Dwarf

  6. Supernova

  7. Neutron Star

  8. Black Hole
• The Sun is the only star that can be observed directly from Earth.
• Spectral types range from O to M, with hotter stars having earlier letters (O-B) and cooler stars having later letters (A-M).
• Stars are classified based on their spectral type, which indicates their temperature and luminosity.
• Stars are classified based on their spectral type (color) and luminosity class (intrinsic brightness).
• Red giants have exhausted their core's supply of hydrogen fuel and begin fusing heavier elements like helium or carbon.
• Red giants have exhausted all fuel sources except hydrogen at their core.
• The main sequence is where most stars spend most of their lives, fusing hydrogen into helium.
• The main sequence is where most stars spend most of their lives.
• Spectral types range from O to M, with hotter stars having earlier letters and cooler stars having later letters.
• Stars are classified based on their spectral type, luminosity class, and chemical composition.
• White dwarfs are small, dense remnants of low-mass stars that no longer generate energy through nuclear fusion.
• Luminosity classes range from V (supergiants) to VII (dwarfs), with brighter stars having lower numbers.
• Black holes form when a massive star collapses under its own gravity.

  
• Supernovae occur when a massive star runs out of fuel and can no longer support itself against gravitational collapse.
• Black holes form when a star collapses under its own gravity.