I have read that a single free neutron is unstable but then how a neutron star can exist ?

The gravity of the star prevents the decay of the neutron. Think of it this way, an neutron takes up less space than the the electron and proton it decays into. So if the neutrons of a neutron star decay, the neutron star would expand. It would have to expand against the gravity pulling it together. If the energy needed to expand against its own gravity is more than the energy released by the decay, the neutrons can't decay. This is why there is a lower mass limit for neutron stars; they have to be massive enough for their gravity to hold them together against the tendancy of the neutrons to decay.

I believe neutrons within neutron stars do decay, cause quakes, and release energy from the neutron star. Even black holes release energy. Few things are stable forever.

I believe neutrons within neutron stars do decay, cause quakes, and release energy from the neutron star. Even black holes release energy. Few things are stable forever.

 

What do they decay into?

 

What do they decay into?

I don't know, but if there are quakes, there is energy being dissipated, and the source must be neutrons from a star made of neutrons.

Edited January 5, 201411 yr by EdEarl

I don't know, but if there are quakes, there is energy being dissipated, and the source must be neutrons from a star made of neutrons.

Quakes on earth aren't caused by neutron decay. They are caused by mechanical instabilities, driven by gravity. Why wouldn't a neutron star act similarly?

Quakes on earth aren't caused by neutron decay. They are caused by mechanical instabilities, driven by gravity. Why wouldn't a neutron star act similarly?

I cannot find the article which I though I had read; perhaps it was a dream.

The surface of a neutron star comprises protons, electrons and compounds. I imagine it just like a chemical equilibrium: deep enough, the pressure favours the denser form, that is neutrons. And the equilibrium means transformations in both directions, with pressure accelerating the transformation into neutrons.

The gravity of the star prevents the decay of the neutron. Think of it this way, an neutron takes up less space than the the electron and proton it decays into. So if the neutrons of a neutron star decay, the neutron star would expand. It would have to expand against the gravity pulling it together. If the energy needed to expand against its own gravity is more than the energy released by the decay, the neutrons can't decay. This is why there is a lower mass limit for neutron stars; they have to be massive enough for their gravity to hold them together against the tendancy of the neutrons to decay.

i think this may be the right reason