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[deleted] t1_ivi10kb wrote

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[deleted] t1_ivi5bwi wrote

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[deleted] t1_ividka7 wrote

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[deleted] t1_ivie7jd wrote

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[deleted] t1_ivilbli wrote

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TaylorCountyGoatMan t1_ivi74wo wrote

It’s a giant ball of frozen nuclear explosions.

That’s awesome.

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thr33pwood t1_ivj9vgp wrote

As far as I know there is no nuclear fusion happening in neutron stars. The parent star collapsed in a supernova because it ran out of fuel for the fusion, which was counteracting the gravitational force.

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[deleted] t1_ivjhl48 wrote

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go_half_the_way t1_ivjj5to wrote

Wow. So if it’s giving off enough light to be a star how is that energy being generated and how does it ‘get out’ of the solid surface?

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[deleted] t1_ivjjq26 wrote

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Rodot t1_ivjua01 wrote

It's black body radiation, usually taught in stat mech classes when deriving the Planck distribution (distribution of energies in a gas of photons). It's low level mechanism comes from what are called "continuum" interactions. They are called that because they produce a continuous spectrum unlike atomic interaction which are discrete.

Some examples of continuum interactions include Thomson/Compton scattering (photons bouncing off electrons, Thomson scattering is the low energy approximation and Compton is the relativistic case), Bremsstrahlung radiation (electrons scattering off ions), photoionization (electrons being kicked out of their atoms), collisional interactions (atoms and ions bumping into eachother), and autoionization (atoms with multiple excited electrons reconfiguring to shoot off an outer most electron through quantum tunneling). For those for who it's not clear where exactly the light comes from in all of these, accelerating charged particles emit light.

All of these interactions together create the Black-body (or Planck) distribution.

Source: I'm one of the developers of an astrophysical radiative transfer code

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flyingpanda1018 t1_ivkifab wrote

Does the black body spectrum change for a neutron star, given there are significantly less electrons and protons than in normal matter?

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Rodot t1_ivl46ap wrote

It's spectrum is much more complicated because it's very high energy and you need to consider how the light interests with the protons and the structure of the magnetic fields.

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OfLittleToNoValue t1_ivmrwnd wrote

I'm not an astrophysicist, but are you saying electrons are moving so fast they generate light? Isn't light a photon? Where are they coming from?

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Rodot t1_ivmvufb wrote

According to Maxwell's equations, a changing electric field creates a magnetic field, and a changing magnetic field creates an electric field. If you set this up as a set of differential equations you get perpendicular propagating waves in the electric and magnetic fields.

A charged particle moving at a constant speed makes a constant magnetic field. An accelerating charge makes a changing magnetic field which makes a changing electric field etc. which makes an electromagnet wave. The quantization of this field results in the waves propagating as photons.

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OfLittleToNoValue t1_ivoeg6p wrote

But where do the photons come from?

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Rodot t1_ivojlpk wrote

From the electromagnetic field

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OfLittleToNoValue t1_ivoop6h wrote

They just poof into existence? I'm assuming I just don't understand what a photon actually is.

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Rodot t1_ivopmiw wrote

Think of a photon as similar to a musical note when you play an instrument. For a string instrument, you pluck the string and it causes it to vibrate at a specific frequency depending on the length (i.e. it's boundary conditions). This is kind of like a photon but instead of plucking a string you are "plucking" the electromagnetic field and it makes a vibration at a certain frequency depending on the boundary conditions (electrons, ions, etc) of the system.

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OfLittleToNoValue t1_ivorr0q wrote

I understand sound to be the consecutive vibration of atoms which is why sound cannot traverse a vacuum. For light to traverse space is my understanding that is that photos are some kind of discrete particle with mass and that's why things like solar sails work.

From what you're saying, the interaction of the fields creates photons. Is this energy converting into matter and the genesis of a discrete particle?

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Rodot t1_ivorv7u wrote

Photons do not have mass. They do carry momentum though.

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OfLittleToNoValue t1_ivosz7x wrote

Man I feel dumb. What is a photon made of then? It's just energy that flows and glows until it dissipates? Thanks for humoring my ignorance!

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Rodot t1_ivqj6cx wrote

Photons are made of photons. They are fundamental particles

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Bonesmash t1_ivm5n5j wrote

You got some good “how” replies. I just wanted to point out that when a neutron star is made, it’s an extremely energetic event, in addition to it having just been a nuclear fusion reactor. So that’s where the initial heat for the black body radiation came from.

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KenHutchenson t1_ivkc7vj wrote

Wait whaaat!? Neutron stars don’t radiate photons!? Today I learned…that’s so cool.

So to see neutron stars do I need a special telescope?

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8Eternity8 t1_ivkf3rt wrote

X-Rays are photons. Just with higher energy and outside the visible spectrum.

But yes you would need a special telescope to see something that only radiates in the x-ray spectrum.

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SandyDelights t1_ivjmts5 wrote

Objects don’t need to continuously generate energy to produce light – white dwarves are the “dead” cores of stars, but it takes an extraordinary long time for them to radiate away the remnant heat.

The distinction here being they don’t need to generate energy because they already have generated that energy (in the form of heat), so the light (in the case of white dwarves) is just the heat radiating into space as the dead star slowly cools (or causes the star to cool, whichever you prefer).

Good example is a stove burner: turn it on, crank it up to high so it’s burning hot and glowing red, then turn it off, pull the plug if you want to. Does the red go away instantaneously, or does it slowly darken as it cools?

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go_half_the_way t1_ivjn27l wrote

Thanks. Makes sense. So this is an immensely hot solid ball slowly cooling.

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SandyDelights t1_ivjnutq wrote

Oh, not going to say that – I was explicitly answering the general question of “if it’s giving off enough light to be a star now is that energy being generated and how does it ‘get out of the solid surface’”, i.e. you don’t need to produce energy to produce light (you just need some form of energy present for it).

That said, yes, but there are a lot of caveats – this article covers it really well and in fairly simple terms.

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thr33pwood t1_ivjne32 wrote

Despite being very different in nature Both neutron stars and white dwarfs are the remnants of former stars and both emit electromagnetic radiation (light, heat, x-rays, gamma rays) which is left over from the time they were actively undergoing fusion processes.

White dwarfs are the remnants of smaller stars, they are essentially the solid hyper-hot iron core of stars. They radiate heat and light for many millions of years before they eventually cool off. (Note that this will last longer than the universe is old now).

Neutron stars are the remnants of more massive stars. The moment the fusion fuel burns out, there is no force pushing outwards to counteract the immense gravoitational force - and in the case of these stars the gravitational force is strong enough to overcome the repelling force of protons that keeps atoms apart. The force crushes the nucleons together into a neutron soup. This crush generates immense "heat" energy which is being radiated in the form of gamma rays, radio waves and in other electromagnetic spectra until eventually these neutron stars too cool off in the distant future.

Stars that have had even more mass before the fusion reaction stopped, turn into black holes.

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Deafcat22 t1_ivlnmk1 wrote

They also tend to spin real quick! Conservation of angular momentum, coupled with a drastic reduction in radius, greatly increases whatever spin the star previously had.

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Rice-Weird t1_ivmefgm wrote

No protons or electrons?

Was always under the impression neutron stars='normal' sub-atomic elements minus any space between them. You know, like if stong & weak nuclear forces just hugged forevermore.

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[deleted] t1_ivomjl3 wrote

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Rice-Weird t1_ivomrgh wrote

Ahhhh- thank you! This makes perfect sense.

Universal forces are bonkers to learn more about.

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mennydrives t1_ivp817k wrote

Even scarier. It's a giant ball that generates magnetic fields so powerful, they render chemical life impossible.

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[deleted] t1_ivhzvh3 wrote

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[deleted] t1_ivj2gw4 wrote

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K-Zoro t1_ivi4f21 wrote

Wow, that’s freaking cool. A whole new strange thing in the cosmos to ponder about.

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The_Critical_Cynic t1_ivi5e5h wrote

I just wonder how it relates to all the things we thought we knew about stars.

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tameriaen t1_iviefjk wrote

Question for folks who know better: I've heard it theorized that quark stars would have a strangelet-crystal crust (and I have no idea what that would mean for their magnetic field). Based on the data we've got, "is there any reasonable possibility this bizarre is a strange star?"

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MyShixteenthAccount t1_ivkg2j0 wrote

Aren't quark stars black holes?

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tameriaen t1_ivlg460 wrote

We don't know what's on the other side of the event horizon -- could be quark star, plank star, singularity, whitehole universe, or something else. Your guess is as good as mine.

That said, it's thought that neutron stars might have quark matter cores, and there's a handful of stars (without event horizons) as candidates for quark stars.

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MyShixteenthAccount t1_ivlvy6z wrote

I had only known quark stars as proposals for what's inside a black hole, didn't know they could be neutron star cores.

That's interesting.

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humaniteer t1_ivihx4x wrote

How exactly does a magnetic field make things freeze?

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imdfantom t1_iviyawf wrote

So, they're saying that the outer surface could be made of charged particles.

These charged particles are like little magnets (not really but for the purpose of this explanation it works).

The strong magnetic field (from inside the star) fixes these tiny "magnets" in place. Kind of like how iron filings are pushed into specific shapes when exposed to a magnet.

The effect is so strong that the ions act in ways similar to a solid (ie not much movement of particles).

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ProjectFantastic1045 t1_ivinx05 wrote

Radiation folds back on itself as it’s pulled back in by the magnetic force, causing interference that cancels out some/most of the radiation. This essentially freezes the electromagnetic wave radiation by literally stilling it/zeroing it out.

Not a physicist and I’m totally pulling that out of my spurious knowledge of EM wave interference.

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obct537 t1_ivj701x wrote

... Am I missing something here? I've watched enough nerdy YouTube shows to be aware that neutron stars/magnetars have a solid surface for years now. The article talks a fair bit about not finding an atmosphere, I'm guessing maybe that's the surprising detail here? Is this describing a different "solid surface" than I've heard about before?

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thr33pwood t1_ivj8zbn wrote

Now I'm not an astrophysicist or astronomer but aren't they describing a magnetar, which is a type of neutron star? As far as I know all neutron stars are believed to have a "solid" surface.

Solid in this case is misleading, because this is exotic matter. Neutron stars form when large stars go supernova. The collapse and the gravity are so immense, that the neutrons of the atoms that have made up the parent star actually touch.

This is why a neutron star with a 10km diameter has several masses of the sun.

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lazy_elfs t1_iviahfg wrote

Whats the surface temp? If it higher then the melting point of whatever

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antimeme t1_ivioc0q wrote

but it's solid whatever, and not melting

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obct537 t1_ivj868q wrote

(my uber amateur understanding):

Well, it's neutronium I believe, so the melting point is basically "lolwut?"

However, I think in the case of a magnetar, the gravitational/electromagnetic forces make the pressure so impossibly high that it just can't be anything other than a solid, at least on the surface.

Neutron stars are weird as hell though, I could be misunderstanding all of it

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Ixneigh t1_ivj8hct wrote

In trillions of years when the stars go dark, I assume they will be solid spheres of…what? Iron?

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thr33pwood t1_ivjpu39 wrote

No. That would be White Dwarfs.

A magnetar is a type of neutron star. It is made up of densely packed neutrons. It is a form of matter that is unlike anything we know here on earth. All the matter we know, all elements are made up of Atoms. An atom is neutrons and protons(+) surrounded by electrons(-). Atoms attract and repell each other.

Even in the most dense material known on earth there is 99.99999% empty space between any of the actual particles.

In a neutron star, the gravitational force has become so strong that these repelling forces of the atoms are overcome and the cores of the atoms got crushed together.

This is exotic matter unlike anything we have experience with.

Neutron stars are incredibly compact. They are around 10 kilometers across in size while having around 1.4 times the mass of our sun - which is more mass than our whole solar system has.

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Ixneigh t1_ivjtw3e wrote

Ok, what would happen you some how got a small sample? Would it “unspring” into lighter elements?

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thr33pwood t1_ivjvxuw wrote

I am not an astrophysicist, but I believe nobody knows.

This is an interesting question that basically boils down to "is this form of matter stable?".

But if it is not stable in the presence of continued gravitational force, I believe "unspring" would not describe very well what would "or could" happen then. Because hypothetically the amount of potential energy stored in this is magnitudes higher than nuclear fission or nuclear fusion would provide.

If I had to guess a sample of this kind of matter would be either stable (if there is an interaction holding these neutrons together) or it would make all nukes on earth look like a firecracker.

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Sad-Platypus t1_ivng5n9 wrote

I too am not an astrophysicist so we are two both talking out of our depths. But, some other things to think about.

Would it have a lot of potential energy? Maybe in the sense of a phase change (water - steam 100X volume increase) so 1 ml might expand to 1GL in that sense of explosion.

It is my understanding that while the gravity is keeping it all together, most of the "energy" is consumed in the crush when electrons and protons are merged from all the atoms to form the neutron soup. So once that has happened would they spontaneously go back to being atoms if the gravity was removed?

Neutrons are neutral charge, so no electromagnetic forces would try to push the particles apart. Instead, strong nuclear force might keep it all together even without all the gravity.

Free Neutrons are unstable and decay to hydrogen with a half life of 10 min

If I were a betting man, I would think it would be "stable" in the sense that it wouldn't explode itself, but would be highly radioactive in weird radioactive ways we've never seen.

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CodeMonkeyPhoto t1_ivja7w4 wrote

So I’m assuming the intense radiation though is still going to cook you, the gravity it still going to crush you, and the magnetic field will rip you apart. But otherwise one could walk on the surface.

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Johnisfaster t1_ivkqxjh wrote

Imagine if instead of being frozen its actually stopped time.

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Scako t1_ivjfjyw wrote

This is really cool, I’m imagining what it would be like to be on a planet observing this star up close

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postart777 t1_ivljfzm wrote

The universe is so, so wild.

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