When about 99 percent of the gas and dust materials in a region of space come together under the influence of gravity, they can lead to the formation of celestial bodies. In the context of star formation, this process typically results in the creation of a protostar. Here's an overview of how this process works:
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Gravitational Collapse: Dense regions within molecular clouds (also known as stellar nurseries) begin to collapse under their own gravity. As the material collapses, it increases in temperature and density.
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Formation of Protostar: As the gas and dust accumulate, they form a protostar at the center of the collapsing material. The surrounding material continues to spiral in, and as it does, it forms an accretion disk.
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Heat and Pressure Build-Up: The gravitational energy released during the collapse heats the core of the protostar, leading to increased pressure and temperature.
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Nuclear Fusion: Eventually, when the core temperature becomes high enough (around 10 million Kelvin), nuclear fusion begins. In stars like our Sun, hydrogen nuclei fuse to form helium, releasing a tremendous amount of energy in the process.
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Formation of a Star: Once nuclear fusion starts, the object becomes a true star. It reaches a state of hydrostatic equilibrium, where the outward pressure from fusion reactions balances the inward pull of gravity.
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Additional Formation: The leftover gas and dust around the star can eventually lead to the formation of planets, moons, asteroids, and other bodies in a protoplanetary disk surrounding the new star.
In summary, gravity plays a crucial role in the formation of stars and planetary systems when it acts on the gas and dust present in space.