Why don't stars explode? What holds them together?

[Spin_Network]

stars are in a state of hydrostatic equallibrium. outward radiative pressure from photons and nuetrinos emitted in he core are balanced by the inward force of gravity.

So are we stating that the inward force of gravity, squeeze's photons out from the inner core, similar, like a "wet sponge" expelling water when squeezed, so to speak?

 

[SpaceTiger]

stars are in a state of hydrostatic equallibrium. outward radiative pressure from photons and nuetrinos emitted in he core are balanced by the inward force of gravity.

Photons are only the dominant source of pressure in stars much more massive than the sun. In most stars, it is the particles themselves that are doing the pushing, not the photons (and certainly not the neutrinos).

 

[franznietzsche]

stars are in a state of hydrostatic equallibrium. outward radiative pressure from photons and nuetrinos emitted in he core are balanced by the inward force of gravity.

While this is technically true, as SpaceTiger pointed out, radiation pressure is insignificant in the case of the sun.

I whipped this up in Matlab real quick to demonstrate. The graph is on a log scale, so the 10^# you see on the y-axis is the same as that part in scientific notation. it had to be log scale for the gas pressure to even be noticeable on the graph. A difference of 10^4 is a factor of 10,000 difference between the two.