HOW ARE 'STARS' FORMED?

Stars are born within giant clods of dust and gas known as molecular clouds. These clouds remain cold and dormant for thousands of years. However, when massive energy is released either from a distant supernova or some streaking come, turbulence is created within these clouds. Particles within the clouds collide, giving rise to small knots or clumps with sufficient mass and therefore a stronger gravitational pull. The gravitational pull attracts more particles from the surrounding clouds, resulting in the collapse of the gas and dust. As the clump attracts more mater from the cloud, its centre begins to heat up. Known as a protostar, it is this hot core at the middle of the collapsing cloud that will, one day, become a star. However, the process could take millions of years. When the temperature reaches around 7 million kelvin, the hydrogen atoms start fusing, producing helium and energy. This is called nuclear fusion. When the outward pressure o energy resulting from this fusion counteracts gravity's inward pull, the young star stabilises and become a main sequence star. 

HORSE-HEAD NEBULA

(Example of an active region of star formation)