a protostar has a high enough )_____( to become a star
volume
mass
temperature
brightness
A protostar has a high enough mass to become a star.
To explain why mass is the correct answer:
When a cloud of gas and dust in space, known as a nebula, collapses under its own gravity, it forms a protostar. As the protostar continues to attract and accumulate more mass from its surroundings, its gravitational pull becomes stronger.
The critical moment when a protostar transitions into a star occurs when the density and pressure at its core become high enough to initiate nuclear fusion. Nuclear fusion is the process in which hydrogen atoms combine to form helium, releasing a tremendous amount of energy in the form of heat and light.
The more mass a protostar has, the stronger its gravitational pull will be, causing a higher density and pressure at its core. This high density and pressure allow the protostar's core temperature to increase until it reaches the critical temperature required for nuclear fusion to occur. The initiation of nuclear fusion marks the birth of a star.
Therefore, the mass of a protostar determines whether it can achieve the necessary conditions for nuclear fusion and become a full-fledged star.