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Questions tagged [neutron-stars]

A neutron star is the final stage of the graviational collapse of a massive supergiant star. Except for black holes, neutron stars are the smallest and densest currently known class of stellar objects

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Solving TOV equations that describes neutron stars in modified f(R, T) gravity

Sorry for the long post, tldr at bottom. I'm trying to use standard RK4 code in C/C++ to solve a coupled system of 2 modified TOV equations in f(R,T) gravity and reproduce some of the results of this ...
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How can we model the primordial Universe while the interior of a neutron star and comparable states of matter are still mostly unknown?

There is something I never quite understood about the physics of the primordial Universe. There are states of matter at high temperature/high pressure that are still, today, poorly understood. The ...
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Numerically solving frame-dragging equation in Hartle-Thorne formalism

I'm trying to write a Python code to implement Hartle-Thorne approximation formalism for rotating neutron stars. In this formalism, I am required to solve the following second order differential ...
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Are pure quark stars possible?

Has it been established that structures formed from quarks (like quark stars: https://en.wikipedia.org/wiki/Quark_star) are possible in principle ? I have read about the possibility that inside ...
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Strength of a phase-transition

I'm currently studying neutron stars for a summer research project, and it uses the terms 'weak' and 'strong' transition for nuclear matter in its literature. Can someone explain (in terms that a ...
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Mass formation of a neutron star Vs White dwarf

I have been researching the different outcomes of a star's death. I understand that the main factor is the star's mass at the end of its life, along with others such as its metallicity. Well, the ...
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Does the formation of a neutron star always require a supernova explosion?

Is a supernova explosion an essential condition for the formation of a neutron stars?
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Supressing proton and neutron decay?

I was wondering whether the decay of neutrons and protons (if they happen to be able to decay, as it is predicted by some GUTs) could be avoided in some cases. Let's begin with neutrons: In principle ...
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What is known about the isotope distribution of neutronium decay?

Sometimes it is known to happen. For example, neutron star mergers might result in unstable neutronium droplets which lose the enormous pressure that makes them stable. A "nucleon" of $10^{...
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Neutron Star formation Entropy

When a neutron star forms, is its entropy lower than when it was in the form of the star core. In the case of a black hole the entropy becomes the surface area, so what happens in a neutron star ...
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What would the collapse of a neutron star into a black hole look like from the center?

I have read this question (unfortunately this mentions supernova and not black hole): If it it the latter, then the instabilities that lead to the collapse of a neutron star would begin near the ...
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How do neutron stars overcome neutron degeneracy?

In a white dwarf, the star is prevented from collapsing due to the Pauli exclusion principle. If the star is heavy enough, the protons in the star will capture electrons, forming neutrons and ...
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Is there an equation that can predict black hole formation from neutron star formation from supernova occurrence?

If supernovas can be predicted depending on the mass of the a star, (If its more than about 8 times the mass of sun it will eventually go supernova - https://www.space.com/23756-white-dwarf-stars.html)...
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Protons and neutrons inside neutron stars? [duplicate]

Are there any amount of protons, electrons and other subatomic particles inside neutron stars? I wonder if there are protons or electrons inside neutron stars trapped by their gravity and degeneracy ...
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Gravitational waves and EOS in neutron stars

What is/are the gravitational wave observable/s that makes possible to measure the parameter/s of the equation of state of neutron stars?
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Thermal Radiation from Neutron Stars

I'm a little bit confused over the essence of thermal radiation. The thermal radiation is electromagnetic waves, and EM waves are generated from the acceleration of charged particles. So I feel that ...
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At the TOV limit (almost black hole), how much of a neutron star's primordial mass has been converted to energy?

The following rough approximation seems to show a neutron star at its Tolman–Oppenheimer–Volkoff limit of 2.17 solar masses and 12km radius, has gravitational binding energy on the same order as its ...
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Do neutron stars (or really dense stars) contain more volume inside of them than the expected $V=\frac{4}{3}\pi r^3$?

If I understand correctly neutron stars are so dense that general relativistic effects are not negligible anymore. Does this mean that the volume inside of neutron stars is bigger than we would expect ...
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Can Kolmogorov spectrum be used to describe the plasma fluctuations in the atmosphere of neutron star?

I am wondering that whether Kolmogorov spectrum, which describes the energy distribution in turbulence be used to describe the plasma fluctuation in the atmosphere of neutron star. As I know, ...
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Could two rotating binary neutron stars create massive cosmic rays if their magnetic fields overlapped and acted on a volume of gas?

The so-called GZK cosmic rays sometimes have an energy equivalent to a baseball moving at 30 m/s. The source of these rays has yet to be determined. Could 2 rotating neutron stars orbiting one ...
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Are black holes neutron stars with more mass?

As we know, a star that is too massive to become a white dwarf becomes either a neutron star or if it is even more massive, a black hole: neutron stars form with great gravity that comes with great ...
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Just a theoretical question about the geometry and form of the Black Hole

This is just something theoretical so please do not answer with a whole bunch of data but with a logical presumption about the next theoretical scenario.. There is a collision between a not so big BH (...
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Why is the least massive neutron star less massive than the most massive white dwarf?

Martinez et al. (2015) gives an example of a neutron star with mass as low as $1.17M_\odot$ (solar masses). There is also the recent discovery of this candidate neutron star which is apparently only $...
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Why the Fermi's energies of the proton, neutron and electron are related in this way in a neutron star?

I'm referring to this answer made by ProfRob about why neutrons are stable against beta decay in neutron stars. I've partially understood the answer: when the Fermi's momentum of the electron $p_f = (...
nervousdog's user avatar
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Is being just slightly off about escaping a neutron star lead you back to the surface?

So lets say if there is a hypothetical space craft capable of surviving the gravity of the neutron star and the heat, and say they are on the surface of a neutron star that is about 2.2 times the mass ...
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Would a black hole instantly form when a neutron star slips below the phantom event horizon?

So lets say we have a neutron star that is just few inches away from the phantom horizon and only needs 500 kg before collapsing. So lets say hypothetically that a ship that is designed to survive the ...
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Finding the (idealised) minimum radius of a neutron star using SEMF

If one considers the Semi Empirical Formula (SEMF) in nuclear physics containing the Volume, Surface, Coulomb energy and Asymmetry Energy terms for the binding energy of a nuclide, then by replacing ...
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How do we know the chemical composition of the crust of neutron stars?

Although neutron stars are mostly made of neutronium, the pressure at the surface is not very high which allows regular atomic matters to exist. Emission spectrum can reveal the chemical composition ...
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Does the gravitational redshift obey the Stefan-Boltzmann law?

Here is a non rotating neutron star emitting perfect black body radiation from its surface. Supposing that the radiation is redshifted by a factor of 2 for distant observers (which is chosen purely ...
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Is the existence of hydrostatic relativistic objects a coincidence or inevitable?

Neutron stars are unique in the universe because their sizes are just slightly bigger than their Schwarzschild radii. Because their sizes are comparable with their Schwarzschild radii, the nonlinear ...
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Particle motion due to frame dragging near a pulsar?

PSR J1748−2446ad is the fastest known pulsar rotating at 716 times per second. This neutron star is estimated to have a mass of less than two solar masses and a radius of less than 16km. The linear ...
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Meaning of Left-Right Arrow in a Fitting Formula [duplicate]

I initially posted this question on Astronomy Stack Exchange but the site seemed rather inactive so I will try to ask it again on Physics, hopefully it doesn't go against any rules. I was reading this ...
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If the reduction in Grav. PE in falling into a large Neutron Star approaches $mc^2$, shouldn't we conclude that a black hole is a large Neutron Star?

If we integrate the potential energy due to surface gravity from the surface to infinite radial distance (deep space), with a bit of basic calculus we should get $\Delta E = mgr [J]$. This depends ...
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Why is the common envelope ejected in some accretor-donor systems?

As an example, let us consider a binary system of a neutron star and an evolved star (e.g. red giant) that has expanded, filled its roche lobe, and started the mass transfer onto the neutron star. ...
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What is the core temperature of neutron star as a function of time?

I wish to know about the temperature of the bulk (not just the surface) of a neutron star. I am especially interested in the highest temperature part which I assume is the core, but would want to know ...
Andrew Steane's user avatar
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Do Neutron stars have free quarks?

Do Neutron stars have free quarks? Also Can Quark Stars be formed also due to this reason? Because of Asymptotic freedom high energy causes quarks to be free but according to the mass-energy ...
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How to understand the total proper mass?

In Wald's General Relativity, page 126, he difined a function $m(r)$ as $$ m(r)=4\pi\int^r_0\rho(r')r'^2dr', $$ where $\rho(r)$ is just the $\rho$ appeared in a perfect fluid stress-energy tensor. ...
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Is it possible for two neutron star to merge into a larger neutron star?

Is it possible for two low mass neutron star to merge into a larger neutron star, or will this always result in a black hole? What would this event likely look like?
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Do gravitational waves change the period of spinning neutron stars?

I imagine that gravitational waves can increase and decrease the diameter of a neutron star as they pass through it.Do they alter the speed at which it spins?
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Approximation concerning gravitational waves from binary neutron star

I'm interested in studying two neutron stars orbiting each other and producing gravitational waves. In textbooks the calculation for the power of the radiation is done by considering the neutron stars ...
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If a star ran out all hydrogen fuel and still could maintain equilibrium by some outer forces, what would it then look like without its gases?

We know when a star runs out of its main hydrogen fuel, thermonuclear fusion ceases. Gravity stars pulling it and there is no force anymore to counter the gravity so the star crashes or dies at a ...
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Pulsar rotation

Pulsars are said to be spinning objects from which two beams of radiation emanate in opposite directions. Observed pulse rates range from on the order of one pulse per second to hundreds of pulses per ...
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Neutron star vs. Islands of stability

"Neutron stars" are said to be almost entirely composed of neutrons. The islands of stability principle recognizes an upper limit to the number of neutrons that can be introduced to an atom. ...
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Why is magnetic flux conserved in neutron star formation?

So in studying the topic of neutron stars I've encountered one particular detail that I've found no good explanation for. Most resources I have found say that the strong magnetic fields of neutron ...
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2 answers
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How can there be superconducting protons and neutrons inside an incredibly hot neutron star?

It is hard enough for me to try to wrap my head around the idea of superconducting particles other than electrons (especially neutrons!), .... Given the insanely hot temperatures inside a neutron star ...
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Do the free neutrons in a neutron star sometimes decay and immediately re-form?

Is there any way of confirming this, one way or the other? Would it affect any of the star's 'observeables', so to speak? I know that two similar questions are up on Stack Exchange-physics, and I ...
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What portion of a neutron star's mass is in the form of gravitational energy? [closed]

The reason this question is being asked is that in the case of black holes around 100% of their mass is stored in their gravitational field and I am wondering if neutron stars come close. It is known ...
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What are phenomenological models and ab-initio models in terms of dense matter?

I've tried to grasp the concept of phenomenological and microscopical ab-initio models when it comes to EOS of neutron star matter . I can understand the meaning of them in general, but I find it ...
neutralstar's user avatar
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1 answer
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How does a neutron star "reheat" itself by ohmic dissipation of its magnetic field?

@ProfRob's answer to Neutron star accurate visualization ends with: ...How their temperatures evolve after this is highly uncertain and none have been observed. The problem is that neutron stars have ...
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Neutron star accurate visualization

Has any simulation been done to produce an accurate visualization of a neutron star, as seen from an observer at distances on the order of 1 AU? (Edit: I suppose instead of 1 AU I mean "distance ...
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