SOLAR SYSTEM

Detailed explanation-1: -These knots contain sufficient mass that the gas and dust can begin to collapse from gravitational attraction. As it collapses, pressure from gravity causes the material at the center to heat up, creating a protostar. One day, this core becomes hot enough to ignite fusion and a star is born.

Detailed explanation-2: -A protostar becomes a main sequence star when its core temperature exceeds 10 million K. This is the temperature needed for hydrogen fusion to operate efficiently. The length of time all of this takes depends on the mass of the star. The more massive the star, the faster everything happens.

Detailed explanation-3: -The center of the nebula begins to get hot and dense. Gravity causes light gases to move to the center while heavier materials and ice stay in outer areas. A protostar forms in the center of the nebula. Gravity causes light gases to move to the center while heavier materials and ice stay in outer areas.

Detailed explanation-4: -Within its deep interior, the protostar has lower temperature than an ordinary star. At its center, hydrogen-1 is not yet fusing with itself. Theory predicts, however, that the hydrogen isotope deuterium (hydrogen-2) fuses with hydrogen-1, creating helium-3.

Detailed explanation-5: -When the force of gravity pulling in on the cloud is greater than the strength of internal pressure pushing out, the cloud collapses into a protostar.