Question

A star can be described as a large, hot ball of gas of enormous mass. What keeps this enormous mass from collapsing under its own weight? Identify the forces on the gas that combine to keep it in place and discuss why this delicate balance of forces is stable.

Answer 1

Hey there!

We all know the story of stars. They are enormous, humongous ball of gas, fire and dust. They are in their places without a collapse for millions of years. So how does this happen? What makes it stable?

Well, it all depends on the gravity , pressure , density and the temperature of the star. The star's deep most layer like the earth's core, has to take in all the force of gravity from the surface layer of the star. The surface layer pushes all the weight towards the center (the weight of the gas) and the inner core pushes them outward just because of the gas pressure. So this forms an equilibrium between the inward gravity and the outward gas pressure, thus maintaining the star at an equilibrium position. This equilibrium is said to be Hydrostatic equilibrium.

Just like the same it is important for the star to maintain, the density, temperature and pressure. In the outermost surface, you would know naturally that the pressure would be less towards the center and increases as we move to the core. Hence the temperature and the density also increases as we move to the core. This balance is been maintained by the core when it supports it's own weight through high density , temperature and pressure to maintain and support the outer layer's weight. The core takes all the pressure to make the star in equilibrium position.The balance between the layers through these properties makes the star in the equilibrium position.

This equilibrium through these properties of pressure, temperature and density can only be maintained until the star has it's own fuel, that is until the nuclear reactions take place. Nuclear reactions in the star starts to lessen it's power as the Hydrogen runs out, all other properties also fades away, thus the burning hydrogen in the core wouldn't be having enough temperature, pressure and density to make an equilibrium with the force of gravity from the outer surface.

I hope the explanation helps... Feel free to comment and discuss further... Cheers :)