What is Nova?

About Nova:

• Nova is any of a class of exploding stars whose luminosity temporarily increases from several thousand to as much as 100,000 times its normal level. 
• A nova reaches maximum luminosity within hours after its outburst and may shine intensely for several days or occasionally for a few weeks, after which it slowly returns to its former level of luminosity.
• Stars that become novas are nearly always too faint before the eruption to be seen with the unaided eye. 
• Their sudden increase in luminosity, however, is sometimes great enough to make them readily visible in the nighttime sky.
• To observers, such objects may appear to be new stars; hence the name nova, from the Latin word for “new.”
• Studying novae is crucial to advancing our knowledge about fundamental astrophysical processes, including stellar evolution.
• How do Novas occur?
  • Commonly, novas start as white dwarf stars that are part of a binary star system.
  • Binary stars are two stars that are close together in the distance and revolve around each other. 
  • The white dwarf is small and dense, and it is essentially the insides of a star that lost its outer layers. These are older stars that have lost their shine and fuel.
  • The white dwarf is most likely paired with a red giant. 
  • The white dwarf begins to pull on its companion, the red giant, with gravitational forces.
  • The white dwarf takes fuel and matter, especially hydrogen, from its companion and pulls it towards itself. The matter is quickly hurled towards the surface of the white dwarf.
  • Layers of material from the red giant gather on the surface of the white dwarf. As the layers are created, the material begins to grow hotter.
  • When the layers become compressed and hot enough, the material begins to combust and explodes through thermonuclear reactions. 
  • The hydrogen material begins to react specifically with helium. The explosion of the materials causes the white dwarf to suddenly become bright as it throws off some of the material.