Neutron stars are formed by stars with masses greater
than eight times the mass of our sun. In these stars
there is enough fuel to produce larger quantities of
carbon and oxygen. If the carbon and oxygen core has
a mass greater than 1.4 times the mass of our Sun, the
gravitational forces are strong enough to collapse the
core beyond the white dwarf stage. The carbon and oxygen
will fuse to produce neon, sodium and magnesium.
of these fusion processes have emitted energy to keep
the star burning. But the silicon and sulphur in the
core produce iron when they fuse together. Iron is the
most stable form of nuclear matter, and the fusion of
iron does not emit energy. In fact, iron requires energy
for fusion to take place. The result is that fusion
stops at the very centre of the star.
no radiation from the core, the outer layers of the
star begin to collapse in towards the centre, drawn
by a gravitational attraction. The iron core is pushed
together so tightly that nuclei of iron begin to touch,
before emitting an immense shockwave.
shockwave of very high energy particles spreads outwards
through the star and holds enough energy to fuse elements
together into isotopes of every imaginable element,
including very heavy substances like uranium. The shockwave
also spreads inwards through the core with enough energy
to convert the protons and electrons of the iron into
neutrons. The explosion is so powerful that the supernova
will outshine the rest of the galaxy for a month.