What is the approximate final size of the collapsed iron core just before it rebounds to cause a supernova?
Answer
A sphere only about 20 kilometers across
During the rapid implosion, the core shrinks from a size comparable to Earth down to a sphere only about 20 kilometers in diameter in a fraction of a second.

#Videos
How Does A Red Supergiant Become A Supernova? - Physics Frontier
Related Questions
What initial mass generally qualifies a star to evolve into a red supergiant capable of supernova?What element's formation signals the cosmic dead end for nuclear fusion in the core of a massive star?What is the primary consequence when a star's core converts to iron regarding energy production?How fast can the iron core collapse inward during the catastrophic implosion?What is the approximate final size of the collapsed iron core just before it rebounds to cause a supernova?What process forms neutrons during the extreme compression of the collapsing core?What phenomenon supports a neutron star against further gravitational collapse?Which famous star is provided as an example of a red supergiant?Under what condition does the remnant of a supernova definitively become a black hole?What is the primary role of a red supergiant supernova regarding cosmic element distribution?If placed where the Sun resides, how far might the outer atmosphere of a red supergiant extend?