These supernovae are believed to be the source of heavy metals. Iron, which was in
the core, gets enough energy during the blast to form heavier elements which are
building blocks for planets, moons, asteroids and even new stars.
After the star has gone supernova, the core still tries to stabilise itself. To attain this
stability, the core needs to shrink further as gravity needs to overcome electric forces
of repulsion between two electrons. It achieves this by converting electrons to
neutrons which have neutral charge and compresses the core further. However,
neutrons being much heavier than electrons, the core becomes more and more dense.
The star is still burning, albeit not very brightly, and in this state it is called a
“Neutron Star”. Neutron stars are characterised by their extremely high spin rate, up to
100 times per second and their spectacular magnetic field, which causes clouds of
electrons to align themselves along the magnetic axis. These electrons send collimated
beams of light. They act like lighthouses, when the beam is directed towards us, we
can see them.
The neutron star however, has a limit for its mass too. It is known as the Tolman–
Oppenheimer–Volkoff limit (TOV). It is estimated to be 3 solar masses. When a
neutron star reaches this limit, the core, unable to overcome the gravity, completely
collapses on itself. What is born out of this is beyond our wildest imagination.
As the core collapses, it becomes even smaller and denser than it was, as it does so,
the escape velocity starts skyrocketing. And there comes a time when the escape
velocity touches 300,000,000 m/s. The speed of Light! The old star has now built a
fortress around itself, a reverse shield from which not even light, the fastest known
entity in the Universe, can escape. A BLACK HOLE. The most intimidating entity in
the whole universe, a black hole is the pinnacle of a star’s death. It signifies gravity’s
ultimate victory over any other force. Every non rotating black hole has a ‘critical
radius’, called the Schwarzschild radius, the lowest radius at which a body can orbit
without being sucked into the giant sink. The boundary around the collapsed star
having this radius is called the Event Horizon. What actually happens after the Event
Horizon is traversed is still a matter of speculation, as all the laws of Physics cease to
exist inside the giant doors of doom. Their mystical nature gives rise to innumerable
questions.
If matter disappears inside a black hole, does it appear elsewhere in the Universe? Or
in another parallel Universe? Are wormholes really possible? Can we realise time
travel through black holes? The answers to these questions still elude us, as they lie
hidden in the interiors of these celestial bodies, watching civilisation after civilisation
desperately try to solve these mysteries, patiently waiting for mankind to uncover
them.