What is Nova Explosion?

About Nova Explosion: 

• It is the dramatic instance of a star exploding as it interacts with another, nearby star.
• It’s a one of many, repeated moments during the long, slow, death of two neighboring stars in the same system.
• Astronomers are waiting for the fiery explosion of T Coronae Borealis, also dubbed the “Blaze Star” and known to astronomers as “T CrB”.
  • For T CrB, this nova event happens roughly every 80 years — it's like Halley’s Comet event every 76 years — so, astronomers call T CrB a “recurrent” nova.
  • They believe T CrB’s prior eruptions were observed as long ago was December 1787 and even in October 1217 AD.
  • When T CrB erupts, its luminosity will increase dramatically, making it visible to the naked eye for several days.
• Process
  • The system contains two stars — a white dwarf and a red giant.
  • The white dwarf is an incredibly dense remnant of a once larger star. It’s about the size of planet Earth but with the same mass as our sun.
  • Its neighbor, the red giant, is in its final years of existence and is slowly being stripped of hydrogen by the gravitational pull of the denser white dwarf.
  • This star “cannibalism” causes a tremendous buildup of pressure and heat, which eventually triggers a huge thermonuclear explosion.
  • The explosion doesn’t completely destroy the stars, however, and so this event repeats over time. It can carry on for hundreds of thousands of years.
  • Different nova events have different cycles, ranging from a few years to hundreds of thousands of years.

Q1: What is a white dwarf ?

It is the stellar core left behind after a dying star has exhausted its nuclear fuel and expelled its outer layers to form a planetary nebula. It is what stars like the Sun become after they have exhausted their nuclear fuel.

Source: How to see the September 2024 nova explosion without a telescope