Question #f73f3
1 Answer
The cloud of hydrogen undergoes gravitational collapse and forms globules of dense dust and gas which collapse into protostars and then fuse hydrogen to move into the main sequence.
Explanation:
The cloud of low density hydrogen is generally in hydrostatic equilibrium as long as the kinetic energy of the gas pressure is in balance with the potential energy of the internal gravitational force.
But events like a passing star or colliding molecular clouds or shockwaves can trigger a cloud collapse by increasing the density over the Jean's mass.
As the cloud collapses, it forms a series of dense rotating masses that serve as the stellar embryos. the protostellar clouds continue to collapse by radiating the excess energy. The collapsing cloud eventually becomes opaque and the temperature starts increasing.
When the core temperature crosses 2000K, The H and He atoms are ionized and the material in the core becomes sufficiently transparent to allow radiation to escape. The combination of convection within the protostar and radiation from its exterior allow the star to contract further.
This continues until the gas is hot enough for the internal pressure to support the protostar against further gravitational collapse—a state called hydrostatic equilibrium. When this accretion phase is nearly complete, the resulting object is known as a protostar.
As the accrediting disc clears away, the protostar begins to move into the main sequence. Hydrogen fusion begins in its core and Helium is produced.
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