SOLAR SYSTEM

Detailed explanation-1: -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.

Detailed explanation-2: -With the mass of a star and its chemical composition is known, astronomers can calculate the temperatures within its core. Main sequence stars have a core temperature of 10 million Kelvins. Red giants have a core temperature of 100 million Kelvins. Stars come in a wide range of sizes.

Detailed explanation-3: -It requires high temperatures (> 5×108 K or 50 keV) and densities (> 3×109 kg/m3). These figures for temperature and density are only a guide. More massive stars burn their nuclear fuel more quickly, since they have to offset greater gravitational forces to stay in (approximate) hydrostatic equilibrium.

Detailed explanation-4: -For the fusion reactions to occur, though, the temperature in the star’s core must reach at least three million kelvins. And because core temperature rises with gravitational pressure, the star must have a minimum mass: about 75 times the mass of the planet Jupiter, or about 8 percent of the mass of our sun.

Detailed explanation-5: -Nuclear fusion is a process that combines nuclei in order to release energy. It begins when the temperature in a star reaches about 10, 000, 000 Kelvin.