Birth of stars, an event that happens
continually in the universe, involve a large quantity of matter
in a nebula.
Gas converges in the center of nebula, for the effect of gravity
attraction.
When a big distant star
dies, it explodes as supernova and gives off a large amount of
energy. This energy runs into nebula and upsets the gas. ( You
know stars life's cycle!)
Nebula
Gravity attraction is the force (discovered
by Isaac Newton ) that pulls down an apple from a tree. This
force attracts of all the matter in direction of a common point,
the center of the nebula.
Compression
of the gas in the center reduces volume and increases temperature.
( By the perfect gases' law ).
The nebula consist of the
most simple gas in the universe: hydrogen ( H ),
and this is the most plentiful gas in the universe.
Hydrogen isn't the only gas in this nebula. Infact there are
helium ( gas inside balloon ) and other elements, like cosmic
particles dust.
This particles are molecols (or a group of atoms).
Nebulae consist of:
Nebula ( the
"factory" that makes stars ) has size can reach one
hunder light years. That is, if you would across it (at the light
year velocity) you spend about one hunder years.
When the atoms of H are merged in the center of nebula, it begins
a process called nuclear fusion. It is the process that gives the
higher energy from matter. Nuclear fusion needs an high
temperature in order of begins.
In the beginning the
nebulas have a temperature of about 100 °K (about -170°C) and
their density is about one hundred of atoms for cubic meter,
hundreds of times the density of the universe around.
In this time, when stars start nuclear fusion, they are called T
TAURI star by the name of a star in the taurus
constellation in the same condition. Usually, since this nebulas
are wide and matter full, there are a birth of many stars. By the
same nebula, so, borns many stars and they makes a "Open
Cluster".