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eightsquare
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Assuming a planet suddenly got enough mass to be a few orders of magnitude more massive than the sun, the planet would collapse to form a black hole, right(irrespective of the core material?)?
DH is basically right, but you are asking a curious question. A "few" is at least two. Two orders of magnitude is a factor of 100 or so.eightsquare said:Assuming a planet suddenly got enough mass to be a few orders of magnitude more massive than the sun, the planet would collapse to form a black hole, right(irrespective of the core material?)?
eightsquare said:1. When the temperatures in the core of the star get sufficiently high, the electrons of hydrogen are ripped out of orbit and we get a plasma of protons and electrons. If the temperatures further rise the protons can come close enough for nuclear force to take over and fusion can take place to give helium. I wanted to know all the main forces at play in such a plasma. Of course there is the electrostatic repulsion between the protons, and the nuclear attraction if they come close enough. Also there is electrostatic attraction between the protons and the electrons but due to high kinetic energy the electrons ever get into orbit. Are these all?
2. During the formation of a Red Giant, the helium core collapses under its own gravity, but the outer layer of the star swells up. Why? What force pushes them outward against gravitational collapse?
eightsquare said:1. When the temperatures in the core of the star get sufficiently high, the electrons of hydrogen are ripped out of orbit and we get a plasma of protons and electrons. If the temperatures further rise the protons can come close enough for nuclear force to take over and fusion can take place to give helium. I wanted to know all the main forces at play in such a plasma. Of course there is the electrostatic repulsion between the protons, and the nuclear attraction if they come close enough. Also there is electrostatic attraction between the protons and the electrons but due to high kinetic energy the electrons ever get into orbit. Are these all?
3. And lastly, in some stable neutron stars, as shown by Landau, the repulsion between the nucleons keeps the nucleons from coming too close together and this is the neutron degeneracy pressure. The neutrons have their own identity here. If the mass of the star is too large and the neutron star ultimately becomes a black hole, I'm assuming the neutrons all collapse to a singularity and have no individual identity anymore?
eightsquare said:"FYI, the protons actually don't get so close as for the strong force to overcome the electrostatic force, the fusion process (at least for a main sequence) is mediated by protons tunneling through the electrostatic barriers into the strong interaction potential well (then fuse)."
Could you elaborate on this please? I didn't get what you mean.
Ok I got the Red Giant part. But regarding the fusion process, if a neutron has greater mass than a proton how does the fusion release energy?
eightsquare said:Assuming a planet suddenly got enough mass to be a few orders of magnitude more massive than the sun, the planet would collapse to form a black hole, right(irrespective of the core material?)?
Gravitational collapse is the process by which a massive object, such as a star, collapses under the force of its own gravity. This can occur when the star runs out of fuel and is no longer able to produce enough energy to counteract the force of gravity.
As the star collapses, its mass becomes more and more concentrated, causing the gravitational pull to become extremely strong. This can cause the star to collapse into a singularity, a point of infinite density and zero volume, which is the defining characteristic of a black hole.
No, black hole formation is not inevitable in all cases of gravitational collapse. The outcome of a collapsing star depends on its mass and other factors, such as its rotation and magnetic fields. In some cases, the star may form a neutron star or a white dwarf instead of a black hole.
While we cannot directly observe the collapse of a star into a black hole, we can observe the effects of black holes on their surroundings, such as the distortion of light and the emission of X-rays from matter falling into the black hole's event horizon.
Currently, there is no known way to prevent a star from collapsing into a black hole. However, some theories suggest that if a collapsing star has enough angular momentum, it may be able to form a disk around the black hole instead of collapsing directly into it.