Nova

Nova
A Nova is an Astronomical phenomenon that begets a spontaneous appearance of a bright apparently new star that will fade in brightness over the period of many weeks or months. The different causes of a nova are as divergent as they come. One Thing is in common however; All Novae or Novas, involve a white dwarf within a near proximity binary system. The Main Classes of Novas are The Classical Novae, Recurrent Novae (RNe) and The Dwarf Novae. All three classes are considered cataclysmic variable stars. 
The Classical Nova
The Classical Novas are the most common form of Nova. The Creation of Classical Novas are probably a close binary system encompassing a white dwarf and either A Main Sequence Star, A Giant Star or a Red Giant Star. The Orbital period of The White Dwarf and it's companion star is around one day to several days long. Over the days of these orbits, the accreted matter of the companion star will be pulled to the surface of The White Dwarf which in turn, creates a dense and shallow atmosphere made mostly of hydrogen. This hydrogen is then heated by the white dwarf and the high temperature rise high enough to ignite causing speedy runaway fusion. The Spontaneous increase in Power and Energy expels the atmosphere into Interstellar Space which then creates an envelope seen by the observer as visible light. This is why a nova can be mistaken for a new star being born. 
Recurrent Novae
Recurrent Novas are novae that continuously bursts in intervals. These type of Novae are rare with only 10 known in Today's World (May 2020) The Intervals typically occurs in the magnitude of decades. 
Dwarf Novae
Dwarf Novae, also known as a U Geminorum-Type Variable Star, is a novae that mocks the same quality of The Classical Novae, except is much dimmer, less Grand, and repeat more frequently than The Classical Novae. ​