ABSTRACT
Here we must go back to the way in which a star produces its energy. When the star is born inside a nebula, it begins to contract and heat up. Hydrogen must be the major constituent and when the inner temperature has reached a value of around 18,000,000°F (1 0,000,000°C), nuclear reactions begin; the nuclei of hydrogen atoms begin to band together to form nuclei of heUum, with release of energy and loss of mass. (Our Sun is losing mass at the rate of 4 million tons (tonnes) per second, but please do not be alarmed-there is left.) When supply of available hydrogen is used up, the star must readjust itself and everythjng depends upon its total mass. ln the case of a star like the Sun, the outer layers will expand and cool, while the core shrinks and heats up; the star passes through the red giant stage and then throws its outer away complcrcl leaving the core as a small, dense white whjcb will, in the fullness of time, lose its light and heat ro become cold and dead. However, a star which is much more massive than the Sun will have a much more violent fate. When the hydrogen fuel is exhausted, different reactions take over, but evcmuaUy there is 3 violent implosion, followed by an explosion. The star burls most of its material away into space in what is termed a supernova outburst, while the core, now made up of neutrons, will be left on ItS own.
