Stars have been studied and revered for thousands of years by ancient scientists. With our technology, we are finding out more about the amazing history of these firmamental wonders. In this section we will explore the time-consuming creation and violent death of stars.
An interstellar cloud,
An interstellar cloud is the nursery of newborn stars, or protostars. But these dark masses of gas and dust are involved way before a star is a star. Interstellar clouds are located on the spiral arms of a galaxy such as the Milky Way. Up to thousands of local regions, called globules, are hidden deep in the cloud. The globules contract under their own gravity, but the balance of pressure and gravity mostly keep them from contracting or expanding too much. Effective cooling and compression from outside eventually cause gravity to win. The globules collapse and many end up as stars millions of years later. Three important events happen in the collapse of a globule. It rotates faster an the temperature and pressure increase inside the globule. Centrifugal forces are brought in by the increase in rotation speed. They shape the collapsing globule into central core surrounded by and disk and this is called a protoplanetary disk. The central core is what becomes a star. In the duration of the globule collapse, the temperature inside gradually climbs to millions of degrees. As the temperature climbs, dust particles break up into atoms. The atoms in turn break into atomic nuclei and electrons. When the central temperature reaches ten million degrees, its components, mostly hydrogen ignite. The nuclei of hydrogen collide and meld into nuclei of helium. The globule collapses until it is a million times smaller than its original size. This intense compression is combined with a huge boost in pressure. The globule's rise in temperature augments this pressure. The pressures build up and create a force to oppose the gravity. The two become balanced again and the collapse stops. A star is born.
The Eagle Nebula,
a famous interstellar
How long a star lives depends greatly on how big it is. Larger stars die much quicker because they are hotter and they burn their nuclear fuel faster. It is a lot like a cars and how it uses its fuel. The nuclear fuel acts as the pressure that was involved in the making of the star. Once it is exhausted, the outward forces (pressure) stop and gravity takes hold, pushing the star inward. After all the fuel is used up, the core collapses, but there are different categories for the way a star dies. When a star is smaller than the sun, it is called a dwarf star. Theses simply grow dimmer and cooler until they disappear from space. If the star is approximately the size of the sun, it turns into a white dwarf. A white dwarf is a spherical diamond about the size of Earth, and it's made up of carbon and oxygen. The white dwarf then fades away slowly like the smaller stars until it is completely dead. If it is a couple times larger than our sun, the death is a little more violent. A shock goes through the entire star and it explodes as a supernova. The explosion is as bright as a whole galaxy! A neutron star, a celestial body made mostly of tightly packed neutrons, is left in the star's wake. When a star is more than twenty times larger than the sun, it doesn't stop collapsing. It simply collapses into itself until it implodes and bends the structure of space and time. This is called a black hole.
Larger stars- a few million years
Stars about as large as the sun- approx. 10 billion years
Smaller Stars- 100+ billion years (some have been known to live a trillion years!)