Neutron Stars

[mikefear]

These little suckers are crazy..

Because neutrons have no electrical charge, neutron stars are much more compacted and dense..typically 1/30,000 to 1/70,000 the size of our sun; typically the radius of a neutron star is a mere 10-20km.. while being small, they still pack the mass of about 2 solar masses.. that's ridiculous: they are a 70,000th the size of our sun, and still manage to have twice the mass..

Neutron stars are the city-sized spheres that remain after stars are destroyed in supernova explosions. They are incredibly dense – a teaspoonful of neutron star material would weigh a billion tons.

The escape velocity (the speed something is requird to be traveling at in order to escape the gravitational pull) of a neutron star is about half the speed of light, or about 150,000km/sec.

Neutron stars are seemingly formed from the death/supernova explosion of a star about 20-30 times the size of the Sun.

Another interesting piece of info, because of the size and density, a neutron star rotates at about the rate of 38,000 times per minute or 660 times per second.. compared to the Sun which rotates ONCE every 28ish DAYS (13 times a year)!!


Just wanted to share some interesting facts with you guys.. I was reading a book last night at Barnes & Noble called Dark Cosmos: In Search of Our Universe's Missing Mass and Energy ( http://www.amazon.com/Dark-Cosmos-Search-Universes-Missing/dp/006113032X ) and I came across an interesting piece on neutron stars so I came home and did some research.. pretty cool little buggers out there.

 

[blut wump]

The poor things sit there thinking that if only they could have been a shade larger they might have made it to being a black hole.

I don't recall reading that their compactness comes from having no electrical charge. More that the gravity / mass wasn't only strong enough to take them to the point where their collapse could take them to a black hole.

Normally forces due to the Pauli exclusion principle prevent atoms intruding upon one another. This basically states that no two electrons can occupy the same quantum state or, effectively, be in the same place. As gravity pulls the star in on itself, the densities get higher and the electrons are boosted to higher energy levels. As the speed of the electrons gets to a point where they would acquire infinite mass, the atoms collapse and a neutron star results. If the star is massive enough to overcome neutron degeneracy from the strong nuclear force, which prevents neutrons occupying the same space or quantum state, then a black hole results.

 

[blut wump]

It's interesting though, to consider what is matter actually composed of. In and of itself, I guess it's a silly question since matter is just matter but how much of matter is just emptiness?

An atom we think of as mostly emptiness with an electron probability cloud around it. Much as the Earth with the Moon spinning around it has lots of empty space between the Earth and Moon. The idea that a nucleus could collapse, though, would suggest that it is as empty as the next level up. Is matter nothing more than some speck of somethingness at the extent of the Plank's length with peculiar forces somehow emanating from it to provide solidity?

I expect a quantum viewpoint makes this classical questioning into nonsense.

 

[mikefear]

Well, according to the book, the reason that a neutron star is able to become so dense is due to the fact that there is no charge to create any type of repulsion between atoms.. this further accelerates its ability to be as compact as it is.

The book was really well written and easy as hell to understand.. written in very lay terms.

 

[blut wump]

Atoms should, charge-wise, be neutral since electrons and protons balance one another. An atom's nucleus, on the other hand, is positively charged. Since the neutron star is, supposedly, composed entirely of nuclear matter, there should be a huge positive charge to account for.

I guess the author was avoiding mentioning the Pauli exclusion or, maybe, he discusses it in a later chapter.

 

[mikefear]

maybe.. i'll check it out later tonight, i am going back to the book store.. i was gonna buy it, but its only like 180 pages and its 25$

 

[NJL52]

Atoms should, charge-wise, be neutral since electrons and protons balance one another. An atom's nucleus, on the other hand, is positively charged. Since the neutron star is, supposedly, composed entirely of nuclear matter, there should be a huge positive charge to account for.

I guess the author was avoiding mentioning the Pauli exclusion or, maybe, he discusses it in a later chapter.

Neutron stars are composed of just neutrons not atomic nuclei. So they are just a giant blob of neutrons(neutral charge.)

I expect a quantum viewpoint makes this classical questioning into nonsense.

lol yup. Basically, quantum divides sub-atomic particles into sub-sub-atomic particles. Neutrons, Electrons and Protons are composed of quarks, leptons and gauge somethings(forget second word.)