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===== Neutron Stars =====
{{:neutron_star.jpg|:neutron_star.jpg}}

Neutron stars are the most dense objects currently known in the universe, 
having densities up to several times those of nuclei. Also, neutron stars
are also made of mostly nucleons bound together by gravity. Due to this 
similarity in density and composition it is plausible to extend the equation 
of state which governs nuclei to these exotic stellar objects. This 
cannot be applied without caution however, because there are certainly
differences between nuclei and neutron stars. 










===== How are they formed?  =====
The way stars end their lives is highly dependent upon the amount of mass
that they contain. Average mass stars such as our sun lack the gravitational
energy to produce dense matter objects such as neutron stars or black holes
and will simply shed their envelopes becoming white dwarfs. They may however
gain sufficient mass through a binary partner to push them over the
chandrasekhar limit at which point electron degeneracy pressure will not be
sufficient to stave off gravitational collapse to a neutron star.

**White Dwarf**

{{:white_dwarf.jpg|:white_dwarf.jpg}}

Stars more massive than our sun will explode and compress their cores into
extremely dense objects that will either become neutron stars or black holes.
There is a limit to the mass that neutron stars can contain. This boundary
is near 3 solar masses, at which point the neutron degeracy pressure is not
sufficient to stave off the pull of gravity and the star will collapse under
its own gravity into a black hole. The limit for a star to form a neutron star
and not a black hole is entirely dependent on the amount of matter that is
expelled from the core into the interstellar medium. This means that a relativly
small 4-8 //M// star may create a neutron star if little of the outer gases are lost
in the explosion, while a large mass star 25-40 //M// star may also form a
neutron star of most of the material is lost from the star.




===== Properties of neutron stars =====

Neutron stars are very dense bodies created from the collapse of stars. Due to
this great density they are much smaller then their diffuse progenitors. While
a star may have a diameter of a million kilometers the diameter of a neutron
star is much smaller, on average only 10 or so kilometers across. This great 
density increase creates very unique properties such as extremely high 
gravitational and magnetic forces. Also, because momentum must be conserved 
neutron stars spin at a phenomenal rate measured as a few seconds in the 
slowest cases, and down to milliseconds in rare cases.

The rapid rotation of these neutron stars can produce emissions which seem to
pulse when viewed from earth. These emissions can occur at virtually any 
wavelength in the spectrum, and are characterized by being at equally spaced 
intervals. Neutron stars which produce these events are called pulsars. Also
there are neutron stars with exceptionally high magnetic fields that are the 
strongest known magnets in the universe. While their formation remains a
mystery they are never the less thought to be the strongest magnets in the 
known universe. 







===== Differences between nuclei and neutron stars =====

While there are similar properties between nuclei and neutron stars there are
also key differences. The first major difference is that nuclei are held
together by the strong force and neutron stars are held together by gravity.

Secondly, most stable nuclei have roughly the same number of protons and
neutrons. This is not the case in neutron stars because of the incredible
densities present. This density allows for relatively stable nuclei to occupy
the surface of the neutron star, but as you travel inwards neutrons tend to
dominate.




===== Equation of state =====

Even though there are differences between the neutron stars
and nuclei there are enough similarities to try and extend
the equation of state to include them. If successful this
would allow a greater understanding of these presently
mysterious objects. Also, the very neutron rich stellar
material could aid in understanding how very heavy neutron
rich nuclei behave.