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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Are black holes neutron stars with more mass?
So as we know a star that is too massive to become a white dwarf becomes either a neutron star or if it is massive enough a black hole. Neutron stars form with great gravity that comes with great mass....
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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 = (...
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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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Nuclear level densities and neutron stars
My current PhD. project involves working with nuclear level densities (NLDs). However, I am more interested in the applications of NLDs to astrophysics. I know they are important to in calculations of ...
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Schrodinger's equation solutions for hydrogen in a strong magnetic field
I've read that in the vicinity of a neutron star, the magnetic fields are so strong that (other environmental factors aside) conventional chemistry breaks down because orbitals/electron configurations ...
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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 ...
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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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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 ...
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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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Ruling out stable ud quark matter with neutron star atmospheres
up-down quark matter is a hypothetical form of matter that is more stable than regular matter and is among the more "mainstream" exotic matter proposals. Small pieces of it would act like ...
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Neutron star near black hole mass in a moving frame [duplicate]
Consider a neutron star with a mass close to that necessary to form a black hole. In a moving frame, it has additional kinetic energy, and its energy density should increase.
Why is it not possible ...
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Are there primordial populations of neutron stars and white dwarfs?
There is a well-known prediction that density fluctuations in the first moments of the Big Bang produced primordial black holes. Black holes from stellar collapse have their masses constrained by ...
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What is ohmic decay and why does it happen in magnetized celestial bodies like stars and pulsars?
I've seen term "ohmic decay" mentioned in several papers (example) regarding the decay of magnetic fields in celestial bodies like planets, stars, and pulsars, but I can't seem find a clear ...
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On a magnetar, which force would exert a bigger pull on a 10 kg iron chunk?
On the surface of a magnetar, what would pull harder on a 10 kg piece of iron, the gravity or the magnetic field?
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How big is the core of a supergiant star before it collapses into a neutron star?
What is the typical mass and density of the core of a supergiant star before it collapses into a neutron star?
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Could bound and stable clusters of 6 or 8 neutrons be a good candidate for dark matter?
The recent observation of a tetra-neutron resonance suggests that clusters of 6 or 8 neutrons stand a strong chance of being bound and stable. The shell configuration of a tetra-neutron should be ...
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What would be the consequences of asymptotic freedom and color confinement of QCD for neutron stars?
Neutron stars are conjectured to have densities between $10^{14}$ and $10^{17}\ \text{g/cm}^3$. In the latter limit, the neutrons could be so close that the interaction between them would not be the ...
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Problem solving (numerically) the Tolman-Oppenheimer-Volkov (TOV) equations for any equation of state [closed]
I've been working on a code to solve the TOV equations for a while and recently I've got it right but only for one specific equation of state, the bag model, wich is not what I need since it should ...
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What happens when a neutron star becomes a black hole?
Suppose you have a neutron star that's as close as can be imagined to the required mass to become a black hole, perhaps just one proton mass away from this limit, when it collides with a dust grain ...
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Where can I learn more about degeneracy pressure?
I would like to know where I can learn more about degeneracy pressure.Is it a fundamental constant that is unique for all elementary particles.
Is there a formula for it?.
How is it derived?
If I was ...
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Why is the cosmological constant is taken to be a free parameter if its experimental value is $\sim 10^{-52}$?
I have been studying a paper on neutron stars in Einstein-$\Lambda$ gravity. In this paper, the cosmological constant is considered a free parameter.
Now, isn't the cosmological constant already known ...
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What is the value of the polytropic constant $K$ for a neutron Star?
I need to solve the TOV-Equations for a polytropic EOS, but I don't know what value I'm supposed to use for the polytropic constant $K$ in the EOS and also what the unit for $K$ is.
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What's the minimum possible mass of a stable neutron star? [duplicate]
What's the minimum possible mass of a stable neutron star?
Let's say you have a neutron star and slowly take away it's mass, e.g., either by firing a stream of anti-neutrons or by proton decay, since ...
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Coriolis force on surface of neutron star?
Since neutron stars are extremely rapidly rotating, would there be an interesting effect of the coriolis force on the surface?
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What would happen if someone takes a sample away from a neutron star? [duplicate]
What would happen if someone takes a sample slowly away from a neutron star? Will it gradually change to some "normal" matter with regular atoms? If so, what atomic number will they have?
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The various ways to get the Internal energy of a Fermi gas applied to a simplified neutron star
I'm working on the ultra-simplified model of a neutron star where it is represented as a non-relativistic ideal Fermi gas. All textbooks I had a look at give the well-know formula for the internal ...
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Would the collision of a neutron star and an anti-neutron star destroy the galaxy it happens in?
My question is a follow up to this one: Does the collision of a neutron and anti-neutron produce energy?.
Quoting from an answer:
"The collision of a neutron and antineutron star would initiate ...
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