According to this Neutron Stars start out composed of the same material as White Dwarves, combinations of Helium, Oxygen, Carbon, Neon, Magnesium, and possibly Iron before undergoing gravitational collapse. What I'm curious about and can't seem to find information about is what happens to Neutron Stars when they get old. Are Neutron Stars:

  1. Completely stable once created, barring catastrophic external influences, like running into another star.
  2. Subject to some form of "evaporation" slowly decompressing into their pre-collapse elemental constituents.
  3. Subject to degradation into chunks of pure neutrons that undergo rapid beta-decay and form strange high-mass isotopes.
  4. None of the above apply or we have no idea.

This is related to this question but I'm interested in the natural evolution of Neutron Stars left to their own devices rather than what would happen to chunks artificially broken off them.

  • $\begingroup$ There is a stack exchange for physics and for astronomy. $\endgroup$ – Raditz_35 Sep 11 '17 at 14:09
  • $\begingroup$ Both of which are aimed at way, way too technical a level to be of any use to me. $\endgroup$ – Ash Sep 11 '17 at 14:12
  • $\begingroup$ @Raditz_35 While I can see why you might argue that it's inappropriate by the same token the question I've linked and a couple of others about Neutron Stars and White Dwarves are too. $\endgroup$ – Ash Sep 11 '17 at 14:25

Neutron star "aging" can be twofold:

  • if its mass is above 2-3 Solar masses it will continue collapsing becoming a black hole.
  • if it isn't massive enough it will cool down and end up as a black mass visible only as its gravity distorts light passing by.

This, of course, if there's nothing in the vicinity; neutron stars that are part of a double-star system exhibit a vast range of "interesting" behavior like accretion by stealing matter to its companion.

  • $\begingroup$ For the stars that collapse into black holes, do they stop at the "neutron star" level for any appreciable length of time, or do they just collapse straight through? I'd been under the impression it was the latter. $\endgroup$ – Ben Barden Sep 11 '17 at 14:35
  • 1
    $\begingroup$ It depends on actual mass. For those that are near to boundary, residual thermal energy is enough to prevent further collapse until it is depleted by radiation (mainly neutrinos, if memory assists). $\endgroup$ – ZioByte Sep 11 '17 at 14:46
  • $\begingroup$ @BenBarden Also large but very hot Neutron Stars may pause before their final collapse because the "heat pressure" keeps them expanded. Also, apparently, they can collide and tip over the threshold that way. $\endgroup$ – Ash Sep 12 '17 at 10:20

Neutron stars should be stable -- there's nothing else that they can turn into unless and until they add enough extra mass to become black holes. Their rotation dissipates energy, and so it will slow down, but they will remain neutron stars. In the very long-term, if the universe itself lasts long enough, it can be expected that all neutron stars will collide with each other or with black holes and end up as black holes.


Not the answer you're looking for? Browse other questions tagged or ask your own question.