[2] Evaporating gas globules were first conclusively identified via photographs of the Pillars of Creation in the Eagle Nebula taken by the Hubble Space Telescope in 1995.
Gravity pulls the cloud even more tightly together as the EGG continues to draw in material from its surroundings.
As the cloud density builds up the globule becomes hotter under the weight of the outer layers, a protostar is formed inside the EGG.
If the protostar has sufficient mass, the density reaches a critical level where the temperature exceeds 10 million kelvin at its center.
At this point, a nuclear reaction starts converting hydrogen to helium and releasing large amounts of energy.