Questions tagged [neutron-stars]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
0
votes
0answers
30 views

What's the shortest “safe” distance from a neutron star merger?

Take GW170817 for example, the first neutron star collision picked up by LIGO. Given how much data we got from that event, can anyone figure out what the "blast radius" is, and how far away from the ...
1
vote
0answers
37 views

Can Thorne–Żytkow object (heavenly body) exist in universe?

Can Thorne–Żytkow object (heavenly body) exist in universe? It's a new concept I came across. Are there such heavenly bodies in universe? It's a heavenly body in which a neutron star is present inside ...
0
votes
0answers
24 views

Neutron star modelling with polytrope

I want to model the density profile of a neutron star with 1.4 $M_\odot$ with a polytrope $p=\kappa\rho^{\gamma}$ with $\gamma=1+\frac{1}{n}$. I started with $n=\frac{1}{2}$ and solved the Lane-Emden ...
4
votes
2answers
115 views

Percentage of Neutron Stars that leave the Galaxy

When a neutron star(NS) is born the supernova kick gives the newborn NS a certain boost in a supposed isotropic direction and, depending on how strong the boost is and on the position of the NS at ...
7
votes
4answers
157 views

Why were pulsars not discovered in the visual spectrum?

In 1967, the first pulsar was discovered at a radio observatory in Cambridge. Radio astronomy started around the 1930s, but astronomy in the visible part of the spectrum had been done for a long time ...
1
vote
0answers
38 views

Gravitational $N$-body mergers?

Beyond binary systems and its mergers, have numerical relativity groups computed an approximation to $N$-body GW signals/waveforms or is that a hard unsolved task?
38
votes
5answers
5k views

How do LIGO and Virgo know that a gravitational wave has its origin in a neutron star or a black hole?

It is being said that gravitational-wave detectors are now able to distinguish neutron star waves from those originating from black holes. Two Questions: How do LIGO and Virgo know that a ...
0
votes
0answers
44 views

How does a Thorne Zytkow star die?

A Thorne-Zytkow star is one where a red giant or supergiant contains a neutron star at its core, formed from the collision of the giant with the neutron star. It is believed that one has been found in ...
0
votes
0answers
41 views

Doubt about the Einstein Field Equations (EFE) of a Magnetar

The Schwarzschild solution could be an good model for a planet and a star, without rotation and electric and magnetic charge. Besides the fact that this solution is spherically symmetric. The metric ...
1
vote
0answers
23 views

Strange quarks in neutron stars

Recently I have read that the pressure within neutron stars can be so extreme that it can cause the deconfinement of quarks to form a kind of quark 'soup' and that these extreme conditions allow for ...
0
votes
0answers
37 views

What is inside a black hole? [duplicate]

I'm trying to understand what causes a black hole in terms of it's composition. We know a start can die and collapse into a neutron star, but if the neutro star is not dense enough to create a black ...
1
vote
0answers
37 views

Do different neutron stars have different density?

When stars go supernova, a neutron star may be left over if there isn't enough mass to create a black hole. Based on the mass present, will a neutron star have a varying density or is the radius ...
0
votes
0answers
46 views

Is there a relatively painless way to calculate the radius of a neutron star, given its mass?

I know there are different models based on, as I understand it, different equations of state describing the neutron star mass-raduis relation. I'm not sure what to do with that, though. My math isn't ...
3
votes
2answers
105 views

Where do gravitational waves draw the energy from?

Imagine binary neutron stars inspiral, they generate gravitational wave which carries energy away and causing the pair to become ever closer. Since all wave must carry energy I wonder where do ...
0
votes
0answers
28 views

Is getting nudged from a neutron star to a black hole catastrophic?

A recently released SF book has single neutron star on the veritable edge of collapsing into a black hole... "What's going on with the star?" "It's massive. I mean, like, spit-on-it-and-it'll-...
9
votes
2answers
571 views

Gravitational waves and chirp waveform

When two neutron stars collide emitting gravitational waves, what exactly does the chirp waveform represent and how is it used to infer the distance to the source?
4
votes
3answers
200 views

Why do neutron stars with more mass have smaller volume?

I know about Heisenberg uncertainty which makes more localized neutrons have a wider range of undefined momentum, and Pauli exclusion principle which prohibit neutrons from getting too close or "...
1
vote
1answer
134 views

What is the closest distance for an undiscovered old neutron star and how long would it take to get here? To help people scared of neutron stars

This is to help people who are scared of neutron stars. My questions are What is the faintest a neutron star could be How close could it be and not yet be detected How long would it take to get here ...
0
votes
0answers
91 views

How to calculate the corotation radius?

I am studying this paper: P.Ghosh & F.K.Lamb, APJ, 232, pag.259 (1979) I do not understand how the authors calculate the corotation radius, $r_{co}$, where the matter of the disk has the same ...
0
votes
2answers
66 views

Can an invisible neutron star exist? [duplicate]

Basically a neutron/quark star that approaches it's Schwarzschild radius but doesn't surpass it. Its gravitational force is great enough to not let light escape from it, but not great enough to become ...
1
vote
1answer
90 views

Forming a Neutron Star: inverse $\beta^-$ decay or electron capture?

There are three different kinds of beta decays: $\beta^-$: n $\rightarrow$ p + e$^-$ + $\overline{\nu}_{e^-}$ $\beta^+$: p $\rightarrow$ n + e$^+$ + $\nu_{e}$ electron capture: p + e$^-$ $\rightarrow$...
2
votes
1answer
32 views

Running coupling constants within a highly compressed object

I wonder is it possible. in highly compressed objects, such as neutron stars and black holes, (I'm not sure that this applies to singularities), that the physical conditions within these objects ...
3
votes
1answer
69 views

BCS theory for neutral fermions

As I understand it, Cooper pairs form between two fermions and are the cause of superconductivity. I was told by a teacher that the formation of Cooper pairs and BCS theory requires both fermions to ...
1
vote
0answers
47 views

Magnetar's magnetic field near a black hole (novice question)

Even light cannot escape the event horizon of a black hole. Now, imagine a magnetar orbits a black hole. The magnetar orbits too far to be ripped and consumed by the black-hole. However, its magnetic ...
1
vote
1answer
105 views

How common are neutron stars?

I thought this would be a rather easy question to answer, but it doesn't seem to be addressed anywhere. I haven't even been able to find a paper, article, or page that says it's unknown how common ...
1
vote
1answer
38 views

Neutron Star LMXB Accretion Spin-Up Estimation

I've been asked to estimate how much mass a neutron star in a low mass X-ray binary would have to accrete in order to be spun up to ~300 Hz. I found the conservation formula $\frac{d(I\omega)}{dt} = \...
1
vote
0answers
36 views

Examples of perturbative force-free electrodynamics on top of vacuum solutions?

Imagine I have a solution $A_{(0)\mu }$ for the four-vector potential of vacuum electrodynamics. That is, the solution fulfills source-free Maxwell equations $F^{\mu\nu}_{(0)\;\;;\nu} = 0$ with $F_{(0)...
1
vote
1answer
82 views

Is it possible to test the physical reality of extra dimensions predicted by string theory?

I have no business asking this question since I am not a string scientist but I like to follow science news in phys.org and I read an article dated today Gravitational waves provide dose of reality ...
0
votes
1answer
56 views

Neutron degeneracy pressure and the Schwarzschild radius

Does the Schwarzschild radius exist at the exact tipping point where neutron degeneracy pressure fails? For example, consider a hypothetical neutron star that is being held up just below the limit of ...
2
votes
2answers
88 views

What is the energy required to create a gravitational field equivalent to that a mass $m$ shows?

If the mass of a neutron star in its collapse becomes a singularity, then the resting energy of this gravitational field must be $E = mc^2$ ($m$ = star mass). Is this possibility wrong?
1
vote
1answer
586 views

What will happen if a magnetar gets close to Earth?

I have studied that magnetars are a type of neutron stars which are the most powerful magnets in the Universe. Their field strength can be of $10^{13}$ Tesla or even more. What effect would one have ...
1
vote
3answers
113 views

Does the neutron star collapse from the surface to the center or from the center to the surface?

I think the collapse begins at the surface because in this place the gravity is always more intense than in the center. That's right?
0
votes
1answer
30 views

Phase transition and energy conservation inside neutron star

I'm stuck at the moment with this simple question: If a phase transition from hadronic to quark matter of 1st order with a big jump in the energy density occurs inside a neutron star one can get ...
2
votes
2answers
133 views

Can gravitational waves be emitted from single neutron stars?

I wonder whether GWs can be produced and emitted by single neutron stars, since it is known that typically they must be emitted by a binary system of them. If so, can the source be an isolated cool ...
2
votes
0answers
30 views

How can a neutron star have a magnetic field when its particles are neutral? [duplicate]

I understand that it is a celestial object of very small radius (typically 18 miles/30 km) and very high density, composed predominantly of closely packed neutrons. Neutron stars are thought to form ...
1
vote
2answers
293 views

How can a neutron star radiate when it is neutral? [duplicate]

We know how to define the Temperature of a neutron star, as answered in this question. After watching the Sixty Symbols video about Forging Weapons from Neutron Stars, where the temperature and ...
2
votes
1answer
114 views

What happens when a neutron star loses enough mass to go under Chandrasekhar limit?

Say if a blackhole passes very close by a neutron star at high speed fly-by and eats half of the neutron star. What happens to the other half? Does it blow up in size as the electroweak force pushes ...
1
vote
2answers
340 views

In-between neutron stars and black holes

Current knowledge and theories,...Suggest a maximum mass for neutron stars about 2-3 solar masses, and is generally assumed that black holes are ANY compact object above that or more generally 5 solar ...
2
votes
0answers
52 views

On the conversion of neutron stars in deconfined quark stars

Imagine a neutron star, constituted of nucleons ($p$, $n$) and charged leptons (say $e$ and $\mu$), can decay into a deconfined quark star through some process. Given the Bodmer-Witten hypothesis, the ...
2
votes
1answer
196 views

Free fall time of collapsing non-rotating star in GR according to a distant observer

Suppose a star with a spherically symmetric mass distribution, mass $2\cdot M_{sun}$ and initial radius $R$, undergoes a gravitational collapse after all gas pressure has vanished. The final radius ...
8
votes
0answers
200 views

What is the Chandrasekhar-Friedman-Schutz (CFS) instability, exactly?

I am confused as to what the Chandrasekhar-Friedman-Schutz (CFS) instability is, exactly. It seems to partially refer to this paper (https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.24.611) ...
4
votes
1answer
84 views

Can gravity give neutrons a longer lifespan? [duplicate]

Isolated neutrons have a lifespan of about one minute yet neutrons in a neutron star can have the lifespan of the neutron star itself and not decay into proton and electron. Is the intense gravity ...
0
votes
2answers
177 views

Gravitational Time Dilation Inside a Massive, Non-Uniform, Non-Rotating Sphere

I know the time dilation (relative to an observer at infinity) outside a non-rotating sphere can be found from the Schwarzschild metric to be $$t_{0}=t_{f}\sqrt{1-\frac{r_{s}}{r}}$$ where $r_{s}$ is ...
0
votes
5answers
105 views

How does gravity acts on the electrons to collapse a neutrons star or white dwarfs against the degeneracy pressure?

if electrons is considered as quantum particle in case neutron star (alluding to quantum statistics) how does gravity makes the star collapse? considering the fact that electrons are quantum particles ...
0
votes
1answer
38 views

Question about nuclear reation

In Landau and Liftshitz Volume 5 page 318, it talks about nuclear reaction in high density, where proton reacts with electron and becomes neutron and neutrino: $$A_z+e^- = A_{Z-1}+\nu$$ where $A_z$ ...
1
vote
1answer
75 views

Is there a Neutron Star or Black Hole close to solar system?

I recently read an article where it mentioned that the solar system could be born out of a supernova explosion (death of a previous star). In case there was a supernova, wouldn't there be a ...
-1
votes
1answer
66 views

Why are neutron spectra continuous, with maxima? e.g 252Cf [closed]

I want to know why there is a maximum and then decrease.
3
votes
2answers
228 views

How does a neutron star collision turn mass into gravitational waves?

I heard on the TED Radio hour that in the neutron star collision that LIGO recently detected, some of the mass of the neutron stars was turned into energy in the form of gravitational waves. How does ...
2
votes
3answers
263 views

What is the roundest object in the universe?

I would imagine it to be something that has a few of the following characteristics: held tightly together by gravity. large, relative to the deviation of its topography. has minimal spin. I Googled ...
0
votes
1answer
36 views

Is the R-process the only mechanism for making heavy elements in a neutron star merger?

Is it possible that in the debris field left over from a neutron star merger (kilonova) there are heavy element sized chuncks of (mostly) neutron matter that undergo rapid beta-decay to become the ...