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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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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Thomas Precession on Neutron Stars
We know that Thomas Precession is a relativistic correction that is applied to a particle spin that adds an angular velocity to the spin of the particle that moves along a curvilinear orbit linked to ...
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What does "hard tail" mean in the context of astronomical spectra?
I am currently reading about neutron stars and came across this sentence:
"Often the radius is underestimated because only a hot spot emits or the spectrum contains a hard tail."
I can find ...
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Excluding the case of a neutron star-black hole merger with gravitational wave GW 150914
The paper from LIGO's original gravitational wave detection (PRL 116, 061102 (2016)) defines the chirp mass as
$$M=\frac{(m_1 m_2)^{3/5}}{(m_1+m_2)^{1/5}}=\frac{c^3}{G}\left[\frac{5}{96}\pi^{-8/3}f^{-...
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Non-Comulative nature of Mass-Radius curves of Neutron Stars
For finding the mass-radius curve of neutron stars, we can solve TOV Equations which are constraint equations got by solving Einsteins equations. The boundary conditions are $m(r=0)=0$ and $\rho(r=0)=\...
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Would a head-on collision between two stars create heavier elements?
I was thinking about Przybylski's Star, and I was wondering how it was possible that so many heavy elements ended up in the star, such as einsteinium, californium, berkelium, etc. But there is ...
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LIGO et al: Is it possible to estimate the frequency of GW+EM detections?
In the past few years LIGO and VIRGO have detected a multitude of gravitational events. As far as I know however only GW170817 had a verifiable EM counterpart. Shouldn't it be possible, based on ...
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When a neutron star explodes, its gravity weaken so neutronium may fission, is there a mass defect as lighter elements than neutronium form?
When a neutron star explodes, its gravity weaken so neutronium may fission, is there a mass defect as lighter elements than neutronium form? As we get towards iron energy is released? Or not?
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Could electrons tunnel into protons in a white dwarf and turn it into neutron star?
Just like the Sun, where hydrogen ions tunnel into each other to start fusion, which would be otherwise impossible with this level of kinetic energy, could electrons inside a white dwarf tunnel into ...
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Can black holes and neutron stars aquire relativistic mass due to their spin velocity?
Ok, there are people that believe that black holes are just points but in that case let focus just on neutron stars... If the answer is 'yes' how much percent or promile of the total mass is to be ...
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Is it possible to calculate the upper bound of neutron star mass under idealized conditions?
The precise upper bound of neutron star mass is unknown because the equation of state (EOS) of nuclear matter is still poorly understood. However, there are still theoretical constraints on the ...
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Can a rotating neutron star collapse to a black hole through a reduction in rotation?
It is well known that non-rotating neutron stars cannot grow without bound, since an increase in mass causes a proportional increase in density, and accretion beyond a critical limit would cause it to ...
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What would happen if a teaspoon of neutronium crashed through Earth's atmosphere? [duplicate]
Pretty self explanatory hypothetical. I realize this is probably an impossibility and maybe it'd be more likely to be hit by a small black hole or primordial black hole. I'm just curious, because we ...
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Physical significance of 3rd TOV equation
There are three TOV equations :
$$m(r)=\int_{0}^{r}4\pi \rho(r') r'^2 dr'$$
$$ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \frac{dP}{dr}=\frac{-G(\rho+P)(m+4\pi r^3\rho)}{r(r-2Gm)}$$
$$ \frac{d\Phi}{dr}=\frac{G(m+4\...
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How small would a neutron star be to see the entirety of it?
How small in Schwarzschild radii would a neutron star need to be for its gravity to be strong enough to deflect light emitted from one side toward an observer on the opposite side? I know the figure ...
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Does the collision of a neutron and anti-neutron produce energy?
Following up on this post: Anti-Particle of Neutron, one very important part of it is unanswered. If a neutron collides with an anti-neutron, will it violently explode in a flash of energy? The ...
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What is the time-dilation at the surface of an antineutron star? (Does antimatter generate gravitons, an extension of the SM, as matter does?)
The time-dilation at the surface of a [matter] neutron star is calculated to approximately be four times slower than flat space-time, conventional quantum mechanics treats antiparticles as traveling ...
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Could exotic baryons be stable inside exotic stars?
Neutrons are stable inside a neutron star because beta decay doesn't release enough energy to send the proton and electron up to the Fermi energy. Could this principle apply to baryons that have charm,...
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Possible relation between internal and external magnetic field in Neutron Stars
I am wondering about a topic that disturbs me and regarding which I haven't found enough literature about.
Neutron stars are thought to be highly magnetised objects. Generally one makes the ...
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What really supports neutron stars?
I have read this question (to Andrew's answer, in the comments):
What supports neutron stars is the repulsion provided by the strong nuclear force between closely-packed neutrons. The central ...
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Will a neutron star always collapse into a black hole in the future?
If a star has a mass greater than the Chandrasekhar limit, will it definitely become a black hole in the future or does it need to satisfy additional conditions? Let me explain. Suppose the collapse ...
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Is quark-quark interaction possible under extreme heat and pressure circumstances?
The neutron-rich core of neutron stars, underneath extreme pressure and heat, undergoes a phase transition to quark-gluon plasma. If both heat and pressure are increased to exceed beyond the TOV limit,...
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A hypothetical scenario for the formation of a black hole
According to the definition of the concept of barycenter, the question arose for me as a mental experiment that if there were an ultra-heavy binary system such as two neutron stars so that the center ...
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Is it possible that two neutrons can merge?
At the center of neutron stars are tightly packed neutrons with almost no space between them. Also, proton and electron have all merged (electron capture) forming as much neutrons as possible. When ...
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Does tidal deformation change the volume as well as the shape of a neutron star?
It’s said that according to general relativity, perfect vacuum is Ricci flat, which means variation of the gravitational field only deforms an object without compression or expansion. However, neutron ...
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Can a neutron star/quark star have a photon sphere?
Can a neutron star/quark star have a photon sphere?
A photon sphere has a radius equal to 1.5 times the Schwarzschild radius. Is it possible for a neutron star to have on?
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Why are there no known white dwarfs between 1.35 to 1.44 solar masses?
The Chandrasekhar limit for white dwarfs is 1.44 Solar masses, however the heaveist known white dwarf is only 1.35 solar masses. https://earthsky.org/space/smallest-most-massive-white-dwarf/
What's ...
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Strange matter and star quakes
If neutron stars are able to form into strange matter at its core, wouldn’t this be enough to disrupt it and cause noticeable star quakes?
Edit: Could it cause it to go supernova?
I also know that it ...
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Strange Matter and Neutron Stars
If strange matter is theoretically able to be created in the core of some neutron stars, why don’t we see whole strange stars? Strange matter converts all matter to itself, so it should turn the star ...
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Are there any subtle differences in the gravitational waves emitted from NSNS, NSBH and BHBH of identical masses?
LIGO has detected several NSNS and NSBH merger events. However, it’s difficult to tell their identities directly unless the neutron stars are very light in an NSNS merger (such as GW170817) or the ...
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What’s the maximum amount of angular momentum a neutron star can carry?
For Kerr black holes, the spinning rates can be described by a normalized spin parameter $a=cJ/GM^2$, which takes any values between 0 and 1 regardless of the masses of the black holes. If we use the ...
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What is the strength of Coulomb crystals?
Coulomb crystals are solid crystals made of ions embedded in an electron gas. They constitute much of white dwarfs and the crust of neutron stars. In the case of neutron stars it is known that they ...
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Can black holes evaporate into Neutron stars? [duplicate]
If adding mass to a neutron star eventually makes it a black hole, why do black holes after losing mass through hawking radiation not evaporate into Neutron stars?
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Neutron star forms after merging of white dwarfs?
In the news report 'A White Dwarf Living On The Edge'
(Keck Observatory), Ilaria Caiazzo writes about a $1.35 M_\odot$ white dwarf which was formed by the merging of two less massive white dwarfs:
“...
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What is the size of the magnetosphere of a neutron star?
More precisely, what are the factors that influence that size (mass of the star, spin velocity, accretion disk around it, ... do any of those things matter?)
I tried reading this. I cannot: [paper ...
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Aren't Black Holes Just Neutron/Quark Stars?
Disclaimer:
My understanding of general relativity is rudimentary at best, so bare with me and correct me where necessary. Also, any math in the explanation is appreciated, but try to also keep the ...
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Lifetime of pulsars
According to many textbooks, pulsars have lifetime (the time it would take the pulses to cease if $d(P)/dt$ were constant).
Lifetime is $P/[d(P)/dt]$, $P=$period
Why do P/[d(P)/dt] means the lifetime?
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Is there a max terminal velocity much less than speed of light?
If you had an object falling into, say, a neutron star which had a very great gravity, is there some reason other than an atmosphere that would prevent the object from reaching any arbitrary speed up ...
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Can the surface of a neutron star move faster than light? How length contraction manifests there?
It is known that any Kerr black hole is surrounded by ergosphere, inside which everything rotates around the black hole faster than light. Since ergosphere is greater than event horizon, one can ...
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What would we see if a small black hole hits a large, massive neutron star? [closed]
What would we see if a small black hole hits a large, massive neutron star? I am trying to visualise what would we see what the event horizon of a small black hole would do to the surface of a very ...
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Neutron star - Relativistic mass continuity equation
Neutron stars are relativistic objects. Let's suppose that it's static and spherically symmetric, therefore the metric is:
$$
\mathrm{d} s^{2}=c^{2} \mathrm{~d} t^{2} \mathrm{e}^{2 \Phi}-\mathrm{e}^{2 ...
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