How do Neutron Stars emit light?

First I will say it is apparent they do emit light.

My confusion is in how the light is created.

My understanding is a photon is created when an electron is agitated enough that it jumps into a higher shell (valence? orbit?) and then, not wanting to stay there, jumps back to a lower “shell” releasing a photon in the process.

All well and good so far (assuming I am correct above…if that is wrong let me know).

But in a Neutron Star all the electrons are smushed into the nucleus. How then can the electrons jump around to produce photons? Where are the photons coming from?

A real scientist will be along shortly to give a correct answer, no doubt, but here’s my understanding. Black holes draw matter into themselves due to their gravitational influence; as this matter is accelerated, it gives off energy. Before it crosses the event horizon, some of the emitted energy radiates away from the black hole, making it appear as if the black hole itself is emitting it.

Actually, according to Wikipedia, the electrons aren’t as gridlocked as you might think. Linky.

This would assume the Neutron Star is “feeding” on nearby material. I also think we could distinguish that from a star shining. Black holes that are feeding do not emit light the same way a spherical star does (i.e. the whole black hole is not glowing).

Hmm…that may answer it.

Isn’t that the same as a metal?

I think Cerowyn is actually correct. Pulsars accrete matter from either a companion star or some other matter source, they don’t shine all over either, but emit a narrow pulse.

Pulsars still glow as a sphere.

We do not see a black dot at the center of a Pulsar. We see a shiny dot.


I’m not with you, why do you think they glow as a sphere? Tbh I don’t know how much a neutron star glows, but however much it does it’s certainly not enoguh for us to see it, instead for the ones we can observe we seee narrow beams of em raditiation which ‘pulse’ precisely because they’re not being emittted by the whole surface of the neutron star.

What do you mean by “glow as a sphere”? They emit radiation in a narrow beam.

The Wiki article does mention that the matter is most likely iron.

So, would most of the “shine” come from accretion? If so, would the accretion source typically come from the aftermath of the supernova?

I linked in the OP pictures of Neutron Stars.

Pulsars are a sub-variant of Neutron Star. Neutron stars spin rapidly and IF (note big “if”) the Pulsar is oriented correctly we see the pulse or flash. Other stars mey be pulsars too but unless they are aimed our way we would not see the pulse (imagine looking down on a lighthouse…you will not see its beam of light).

That said we do see Neutron Stars even when they are not pulsing at us.

As such, Neutron Stars shine.

They blip as the pulse hits us but there is still a glowing dot to be discerned between the pulses. It is not a star that seems to flicker completely on then completely off.

This is an artist rendition but they’d look like this (semi) up close.

Hi cmyk, I’m no expert on this topic and from what I understand the exact mechanism of how pulsars emit their radiation is not perfectly understood, but accretion is certainly an essenital part of the process.

Most star systems have two or more stars and I think generally neutron satrs become pulsars due to accretion from their companion stars, thoguh I understand a neutron star in a nebula can become a pulsar due to accretion of the gas in the nebula.

Neutron stars do emit light from their entire surfaces, due to their temperature (which can be in the millions of degrees). They’re still pretty dim, due to their small size, so it’s difficult to see the surface directly, but it can be and has been done. They cool down over time, and eventually do go dark, but that takes a while.

Oh, and if a neutron star is accreting, we’ll see that, too, but it’s not a necessary condition for either the surface blackbody emission nor the polar pulses.

AFAIK, all neutron stars spin crazy-fast, because it’s conserving the angular momentum of its original radius (down to a few kilometers). This generates a strong EM field, which shoots electrons and protons off along the magnetic axis (which isn’t necessarily the same as the rotational axis). This is the “pulse” of a pulsar, if aligned with earth right…

…but do neutron stars also shine with their own light; besides the radiation beams? (I think is what W-a-M is getting at)

ETA: Ahh, thanks Chronos.

Right but how?

My understanding is heat excites atoms and an electron, having absorbed that energy, jumps to a higher energy shell around the nucleus.

The electron wants to be in a lower energy state so, in short order, it jumps back down and gives up that energy as a photon.

If that is in error let me know.

So, if the electron is smushed in the nucleus how does it do this? The atoms may be very hot but how do they emit light in that state?

If I understand correctly, black body (“thermal”) radiation isn’t dependent on electron orbital changes- if it were, objects would only emit light at narrow spectral lines. So what exactly is the mechanism for coupling to electromagnetic energy in the black body example?

All matter emits electromagnetic radiation (blackbody/thermal/heat) if it’s above absolute zero. We emit it mostly as infrared, but nothing starts to emit visible light until the object reaches around 800ºK.

Since the neutron star is hot as hell, and its gravity not strong enough to hold photons in, it shines.