An explosion from outside the nebula
Gravity.
A solar nebula begins to form when a cloud of gas and dust in space collapses under its own gravity. This collapse can be triggered by a nearby supernova explosion, a shockwave from a passing star, or other disturbances in the interstellar medium.
Gravity is the force that causes nebulae to collapse. As particles within the nebula are pulled together by gravity, they begin to clump and form denser regions. This leads to the eventual formation of stars and planetary systems within the collapsing nebula.
When the pressure and temperature of a nebula increase, it can lead to the formation of protostars. As gravity causes the nebula to contract and heat up, eventually nuclear fusion can begin at the core of the protostar, leading to the formation of a new star.
Each star in the solar system starts out in a nebula, a cloud of dust particles and gas.
Gravitational attraction pulls gas and dust together in a nebula, causing it to condense and heat up. When the pressure and temperature in the core of the nebula become high enough, nuclear fusion reactions begin, initiating the process of becoming a star.
In the nebula!
After a nebula, the next stage in the life cycle of a star is usually a protostar, where gravity causes the gas and dust within the nebula to begin collapsing and forming a dense core. Following this stage, the protostar may evolve into a main sequence star, where nuclear fusion begins in its core and it enters a stable period of energy production.
Prepositional phrases that begin with after are adverb phrases: e.g. "The nebula formed after a supernova" meaning the nebula formed afterward.
Prepositional phrases that begin with after are adverb phrases: e.g. "The nebula formed after a supernova" meaning the nebula formed afterward.
What causes spermatogenesis to begin
A stellar nebula.