If there were some way (sub question: IS there some way?) to get neutron star material out of the gravity well of a neutron star, -say maybe a high-speed collision of two such stars- how would that material behave away from the gravity well?

Would it continue to be as dense? What dangers would it pose if you were to approach or touch it?

  • $\begingroup$ How big a chunk did you have in mind? $\endgroup$
    – Frostfyre
    Apr 27, 2016 at 19:18
  • $\begingroup$ I'm curious how size would affect it the behavior. Anything from a few grams to megatons. $\endgroup$
    – St0necr0w
    Apr 27, 2016 at 19:20
  • $\begingroup$ The impact on other objects would be determined by the amount of material present to impact the other object. As a trivial example, consider breaking off exactly one atom/molecule/particle from the star and compare that item's influence on other objects to the influence of the remaining structure of items. $\endgroup$
    – Frostfyre
    Apr 27, 2016 at 19:30
  • $\begingroup$ The most likely result from ramming two of them together would be a black hole. $\endgroup$ Apr 29, 2016 at 2:18
  • $\begingroup$ do you mean neutronium or degenerate matter? because neutronium might be able to exist degenerate matter needs the intense pressure to stay stable. $\endgroup$
    – John
    Feb 22, 2017 at 15:42

2 Answers 2


Neutron stars are not very well understood, unfortunately. The matter on the surface is theoretically different from the matter in the core, due to the increased pressures at depth, but we can examine each layer in detail.


There is actually an atmosphere around a neutron star, or there could be at least. It would be veeery thin, perhaps only a few micrometers, and likely composed of hydrogen and helium. If returned to "normal space" these gasses would likely exist as normal.


Beneath the atmosphere will be solid matter (or possibly liquid if the temperature exceeds about 10^6 Kelvin). The matter will still be mostly charged atomic nuclei crushed into a dense lattice swarming with electrons. This structure would behave metallically, and is thus theorized to be made perhaps of Iron, due to Iron's high binding energy. Iron could be too dense, though, which means the crust could be metallic Hydrogen and Helium. If we lifted this material off the surface, it might expand back into a more recognizable form, either solid Iron or gaseous Hydrogen/Helium. Due to the possible temperatures this material might become plasma.

Inner Crust

Proceeding inward we'd encounter more and more pressure, and so nuclei would be composed of more and more neutrons due to the process of Electron Capture. This process turns a Proton + Electron into a Neutron, at the expense of an escaped Electron-Neutrino. Once these neutrons are formed, they are permanent, and will not turn back into a charged duo. The nuclei at this depth become increasingly unstable, since the Strong Force cannot cope with the number of neutrons. The only thing keeping them in place is the immense gravitational pressures. If we scooped out some of this gunk and set it free most of the nuclei would decay rapidly, releasing radiation and turning into more stable heavy elements. This could potentially become an interesting source of exotic elements if you wanted to risk the process of mining in such conditions.

Outer Core

At this depth the Neutrons are becoming ubiquitous, and electrons and charged nuclei become smaller and more rare. The gravitational pressures involved completely overwhelm the Strong Force binding the nuclei together. Any remaining nuclei would probably still be stable if we removed them, since they have become so small, but there could be some very radioactive isotopes in there somewhere. Mostly all you'd pull out of this goo would be pure neutrons, which are not terribly exciting.

Inner Core

At this point there are ONLY Neutrons present. The Electron-Capture process has eliminated all charged particles, and no nuclei exist. If you could somehow get to this depth to remove this material, it would expand as the pressure was released, and the Pure Neutrons would decay rather rapidly into more stable nuclei.

There is a possibility that the core is composed of some sort of quark/gluon plasma. The neutrons are basically dissolved when subjected to the conditions in the core, but such a material is exotic and not well understood. I would probably want to stay away from it in case it expanded violently upon release.

  • 1
    $\begingroup$ And potentially at the center of the heaviest of neutron stars there could be strange matter aka quark matter. The mass of the star breaks down the nucleons and there's just quarks floating around. $\endgroup$
    – Jim2B
    Apr 27, 2016 at 19:40
  • $\begingroup$ @MozerShmozer So just to make sure I understand, if those heavier elements were removed and smashed onto an asteroid or planetoid, they wouldn't be any denser than they would be if found here on Earth, correct? $\endgroup$
    – St0necr0w
    Apr 27, 2016 at 19:51
  • 1
    $\begingroup$ It is thought that none of these components are stable in empty space. The manner & speed in which they adjust to empty space is different for different components. A blob of pure neutrons decays by beta decay (14 min half-life) and then breaks apart into heavy nuclei. A blob of quarks forms muons & baryons - probably with a spray of other exotic particles. A blob of hyper compressed matter will expand (aka explode) until it reaches equilibrium pressure. $\endgroup$
    – Jim2B
    Apr 27, 2016 at 19:58
  • 3
    $\begingroup$ I imagine the best way to get neutron star material out of a neutron star is to whack it sufficiently energetically with another neutron star. You do NOT want to be a spectator at that event. $\endgroup$
    – Jim2B
    Apr 27, 2016 at 20:03
  • $\begingroup$ @Jim2B I did not know that about a blob of pure neutrons; Very interesting! I guess I was mistaken. It seems most of that stuff would decay if you removed them from the Neutron Star. Definitely would be interesting to see what materials you could acquire, but none of them are going to remain as dense as the star keeps them. $\endgroup$ Apr 27, 2016 at 20:04

If a neutron star material came out of a neutron star then it would immediately create a lot of energy. This is because neutrons would decay into a proton, electron, and an electron antineutrino. The only reason neutrons are stable in a neutron star is due to enormous gravity holding the neutrons and forcing them not to decay. Touching neutron star matter would be bad as neutrons can turn into protons and release energy. Also, strange star matter in the core of neutron star comes in contact with any matter to turn it into a strange matter also.


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