[acapella34]

"Massive stars need higher central temperatures and pressures to support themselves against gravitational collapse"
what does having high central temperatures have to do with gravitational collapse?
is it because if theres higher central temperatures theres more fusion in a given time so more energy being produced and so more molecules at the core gain kinetic energy and escape to the outer regions of the star - which increases the outward pressure of the star: which then prevents gravitational collapse of the star?
at equilibrium of the star is the force of gravity pulling matter to the centre of the star balanced by the force exerted by the molecules in the outer regions of the star?

[Stonebridge]

(Original post by acapella34)
"Massive stars need higher central temperatures and pressures to support themselves against gravitational collapse"
what does having high central temperatures have to do with gravitational collapse?
is it because if theres higher central temperatures theres more fusion in a given time so more energy being produced and so more molecules at the core gain kinetic energy and escape to the outer regions of the star - which increases the outward pressure of the star: which then prevents gravitational collapse of the star?

That's just about it!
The inward gravitational forces need to be balanced by the outward pressure from the fusion reactions. A stable star is in overall equilibrium between these two opposing forces. The more massive the star, the larger the inward gravitational forces.

[acapella34]

(Original post by Stonebridge)
That's just about it!
The inward gravitational forces need to be balanced by the outward pressure from the fusion reactions. A stable star is in overall equilibrium between these two opposing forces. The more massive the star, the larger the inward gravitational forces.

thank you so much stone bridge! could you have a look at my other recent questions im having a lot of trouble understanding astrophysics? its greatly appreciated

[acapella34]

(Original post by Stonebridge)
That's just about it!
The inward gravitational forces need to be balanced by the outward pressure from the fusion reactions. A stable star is in overall equilibrium between these two opposing forces. The more massive the star, the larger the inward gravitational forces.

also could you explain what would happen if the outer pressure of the star exceeds that of its force of gravity - is their an explosion or is that just when the force of gravity exceeds that of the outer pressure of the molecules in the star - there is an explosion? are both of these explosions called supernovae? and does it occur after the star becomes a redgiant or super red giant only?
im sorry for all the questions its just that i have an exam on all this

[internet655]

Hi im new here but have been studying similar stuff, if the nuclear fusion reactions occur more frequently due to higher temperatures and pressure then the radiation pressure exceeds that of the gravitational pressure, depending on the stars mass when this happens a red giant (3 solar masses or below) or super red giant (greater than 3 solar masses) occurs. Its red due to the surface being cooler, a helium flash occurs. This is because the nuclear fusion reactions are still occuring at the central core and the as rate increase the pressure causes the outer core to be ejected in the helium flash as a planatary nebula. The central core then becomes a white dwarf and can go no further i.e a neutron star or black hole due to fermi pressure.
However only in larger stars do supernovae occur, the white dwarfs formed over come the fermi pressure as the gravitational forces are large enough, electrons combine with protons and the core is left with only neutrons. The outer shells surrounding the core then collapse violently. This causes the "explosion" left behind is a neutron star or if further collapse occurs a black hole,

hope i helped a bit ! cheers
Josh.

[acapella34]

(Original post by internet655)
Hi im new here but have been studying similar stuff, if the nuclear fusion reactions occur more frequently due to higher temperatures and pressure then the radiation pressure exceeds that of the gravitational pressure, depending on the stars mass when this happens a red giant (3 solar masses or below) or super red giant (greater than 3 solar masses) occurs. Its red due to the surface being cooler, a helium flash occurs. This is because the nuclear fusion reactions are still occuring at the central core and the as rate increase the pressure causes the outer core to be ejected in the helium flash as a planatary nebula. The central core then becomes a white dwarf and can go no further i.e a neutron star or black hole due to fermi pressure.
However only in larger stars do supernovae occur, the white dwarfs formed over come the fermi pressure as the gravitational forces are large enough, electrons combine with protons and the core is left with only neutrons. The outer shells surrounding the core then collapse violently. This causes the "explosion" left behind is a neutron star or if further collapse occurs a black hole,

hope i helped a bit ! cheers
Josh.

hey thanks for all that! but could you explain what fermi pressure is?

[internet655]

Sure, fermi pressure is also called electron degeneracy pressure pretty much means for the white dwarfs which aren't big enough they can't make electrons exist in the same quantum state so only 2 per energy level in an atom and further collapse requirse 2 or more electrons to be in the same quantum state so this is why smaller stars go no further than a white dwarf