EDEXCEL IGCSE PHYSICS: DOUBLE SCIENCE 复习笔记： 8.2.1 Classification of Stars

• Stars come in a wide range of sizes and colours, from yellow stars to red dwarfs, from blue giants to red supergiants
  • These can be classified according to their colour

   

• Warm objects emit infrared and extremely hot objects emit visible light as well
  • Therefore, the colour they emit depends on how hot they are

   

• A star's colour is related to its surface temperature
  • A red star is the coolest (at around 3000 K)
  • A blue star is the hottest (at around 30 000 K)

   

The colour of a star correlates to its temperature

• This is why white dwarfs, for example, are very hot and red giants are red because they are cool
• Astronomical objects cool as they expand and heat up as they contract, such as when a star reaches the end of its life and becomes a red giant
  • This means that their colour will also change accordingly with their temperature