Astronomy Without A Telescope – Making Sense Of The Neutron Zoo

Article written: 15 May , 2010
Updated: 24 Dec , 2015

The spectacular gravity of neutron stars offers great opportunities for thought experiments. For example, if you dropped an object from a height of 1 meter above a neutron star’s surface, it would hit the surface within a millionth of a second having been accelerated to over 7 million kilometers an hour.

But these days you should first be clear what kind of neutron star you are talking about. With ever more x-ray sensitive equipment scanning the skies, notably the ten year old Chandra space telescope, a surprising diversity of neutron star types are emerging.

The traditional radio pulsar now has a number of diverse cousins, notably magnetars which broadcast huge outbursts of high energy gamma and x-rays. The extraordinary magnetic fields of magnetars invoke a whole new set of thought experiments. If you were within 1000 kilometres of a magnetar, its intense magnetic field would tear you to pieces just from violent perturbation of your water molecules. Even at a safe distance of 200,000 kilometres, it will still wipe all the information off your credit card – which is pretty scary too.

Neutron stars are the compressed remnant of a star left behind after it went supernova. They retain much of that stars angular momentum, but within a highly compressed object only 10 to 20 kilometers in diameter. So, like ice skaters when they pull their arms in – neutron stars spin pretty fast.

Furthermore, compressing a star’s magnetic field into the smaller volume of the neutron star, increases the strength of that magnetic field substantially. However, these strong magnetic fields create drag against the stars’ own stellar wind of charged particles, meaning that all neutron stars are in the process of ‘spinning down’.

This spin down correlates with an increase in luminosity, albeit much of it is in x-ray wavelengths. This is presumably because a fast spin expands the star outwards, while a slower spin lets stellar material compress inwards – so like a bicycle pump it heats up. Hence the name rotation powered pulsar (RPP) for your ‘standard’ neutron stars, where that beam of energy flashing at you once every rotation is a result of the braking action of the magnetic field on the star’s spin.

It’s been suggested that magnetars may just be a higher order of this same RPP effect. Victoria Kaspi has suggested it may be time to consider a ‘grand unified theory’ of neutron stars where all the various species might be explained by their initial conditions, particularly their initial magnetic field strength, as well as their age.

It’s likely that the progenitor star of a magnetar was a particularly big star which left behind a particularly big stellar remnant. Thus, these rarer ‘big’ neutron stars might all begin their lives as a magnetar, radiating huge energies as its powerful magnetic field puts the brakes on its spin. But this dynamic activity means these big stars lose energy quickly, perhaps taking on the appearance of a very x ray luminous, though otherwise unremarkable, RPP later in their life.

Other neutron stars might begin life in less dramatic fashion, as the much more common and just averagely luminous RPPs, which spin down at a more leisurely rate – never achieving the extraordinary luminosities that magnetars are capable of, but managing to remain luminous for longer time periods.

The relatively quiet Central Compact Objects, which don’t seem to even pulse in radio anymore, could represent the end stage in the neutron star life cycle, beyond which the stars hit the dead line, where a highly degraded magnetic field is no longer able to apply the brakes to the stars’ spin. This removes the main cause of their characteristic luminosity and pulsar behaviour – so they just fade quietly away.

For now, this grand unification scheme remains a compelling idea – perhaps awaiting another ten years of Chandra observations to confirm or modify it further.


34 Responses

  1. Olaf says

    Oh oohhh dirty words in the article. . I bet many responses

  2. DrFlimmer says

    It doesn’t fit with the topic of this particular thread, but what I find astonishing are “neutron star-quakes”. The crust moves only a few millimeters, if at all, and releases an enormous amount of energy! I think, some of those outbreaks have been accidentally classified as Supernovae at first.


    [I]f you dropped an object from a height of 1 meter above a neutron star’s surface, it would hit the surface within a millionth of a second having been accelerated to over 7 million kilometers an hour.

    Well, if that object has a mass of 1 kg, and E(k) = ½mv², then the kinetic energy of that object will be over 1.89E+12 joules — equivalent to approximately 452,000 tonnes of T.N.T.


    (I’m relieved that the XML/HTML codes have worked above!)

  5. jimhenson says

    I believe in a grand unification with neutron stars and black holes. Goodsell says a link between cold atoms and carbon nanotubes form atomic black holes with ions orbiting like stars. Davies says W3AA massive protostar is self-similar to small mass star formations. Relativisitic supernovas like SN2009bb have the luminoisity of a quasar with a central engine core, rather then the luminosity of a galaxy for a supernova. Dark matter is not consumed by black holes, cause I believe magnetic fields mistaken for dark matter “gravity” aligns galactic positron anti-matter, accretion disks, and dark matter with the BEC emission jet. Tidal streams clumping into galaxy halos have unaltered dispersion in the leading tail compared to the trailing tail, because I believe black hole magnetism is between merging dwarf with parent galaxies, like in Seyfert galaxies with optical jets. Supermassive blackholes produce a constant gravity visible matter ratio with dark matter within a universal one halo radius and density. Large scale objects like superclusters and galaxy clusters have more accelerated particles then their respective lesser mass objects though size does not matter. Black holes are neutron related, with space from the electron spin becoming fused to the proton. hydrogen atoms like huge alpha lyman blob Himshiko doesn’t have a black hole, and neither did the first born quasars that do not have time dilation, and had little or no dust and gas to grow and feed their black hole. My website has been an ongoing effort to supply data for science from current links on a grand unification objective for self-similarity fractal size scaling of objects.


    @ Jon Hanford,

    You’re welcome! That’s what I’m here for.

    Torbjörn Larsson OM:

    Somewhere a little rabbit is crying now, I’m sure.

    I found that poor bunny here.

  7. Lawrence B. Crowell says

    The idea of a “grand unification” of neutron stars probably requires some understanding of the interior state of these objects. A basic neutron star is a gas of neutrons with Fermi-Dirac statistics. Given enough mass though the interior will become dominated by higher mass baryons, such as the Sigma^0 in the spin 1/2 octet. So the core of the neutron star may be in a different phase in general. For larger neutron stars the core may be dominated by quark-gluon plasma. From the perspective of magnetism this state has analogies to the superconducting state. This may be an aspect of how magnetars function to permit these incredible magnetic field above the 10^{13] Gauss range.


  8. frogstar says

    The recent paper from Kaspi giving a compact overview of neutron star types can be found here:

    (for those of you who like me didn’t notice at first that the name of the author was a link to the paper)

  9. jimhenson says

    none of you people know anything of special value yourself, yet alone anything about the grand unification theory by Einstein. nor do bunnies have anything to contribute for the advancement of science. that’s why you’re so anxious to second request removal post deletions, without discussing serioius science about the relevant topic. Neutron stars have black hole centers that warp space and collide because of dark matter streaming magnetism pulling other stars together. Get your acts together and apply observational phenomena with neutron stars like Kaspi says!

  10. jimhenson says

    The suns solar wind H+ southern hemisphere emission is invisible to us along the magnetic plane of the solar system including earths orbit. extending out to 100 AU is this edge boundary of the solar system that deflects back the solar wind U-turn style. The suns magnetic field is polar with north pole always opposite to earth’s pole. From earth we can only always see and observe just along the East-West equator of the sun. Dark matter invisible magnetic field lines from the suns southern hemisphere tidal streams and pulls together distant gases stars into galaxies etc. white dwarf stars continually merge from brown dwarf and red dwarf stars without a single nemesis for the sun.

  11. IVAN3MAN_AT_LARGE says

    @ Lawrence B. Crowell,

    Here’s a nice illustration of “The Guts of a Neutron Star“.

  12. Jon Hanford says

    Thanks for that link, IVAN3MAN. I see it touches on a topic not mentioned in the above article. I’m referring to the spinup of accreting neutron stars with large magnetic fields ( ). This mechanism is thought to give rise to millisecond pulsars.

  13. Torbjorn Larsson OM says

    Could someone please delete the crackpot comment that spewed irrelevant promotion of “personal theories” on this beautiful page? Somewhere a little rabbit is crying now, I’m sure. (-_-‘)

  14. DrFlimmer says

    I second Torbjorn Larsson’s request!

  15. Olaf says

    Me too: I second Torbjorn Larsson’s request!

  16. Member
    Aqua says

    What I like is that at this distance we have seen motion(s) over time in the pulsar! Rare to see? at least astronomically speaking its so…

    Its alive! with pulsating electro dynamic plasma’s spinning outward around a magnetically constraining toroid. What other incredible properties of matter will we discover as we dig deeper into this mystery? What fantastic engine powers this dynamo? Gravity?

    Interdimensional wormholes anyone? Where FTL is possible in dimension ‘A’? because time itself runs at a different relative rate and/or direction?

  17. Lawrence B. Crowell says

    @IVAN3MAN_AT_LARGE: Thanks for the page on neutron star interiors. I have little knowledge of this area. The interior is of course the question mark. I am not sure we will ever get much data on that.

    @ Jon, What you are mentioning is the sort of inverse of the spin down mechanism. With a huge magnetic field the neutron star will be dragged into a sort of equilibrium with the motion of the plasma medium. A nonrotating medium will slow down the pulsar, and an accretion disk will spin it up.

    @ jimhenson : A black hole in the interior of a neutron star would quickly convert the whole thing into a black hole. Unfortunately what you wrote, now deleted was a potpourri of nonsense. However, just to be kind and throw a small bone here, there might be some AdS ~ black hole physics involved, though there can’t be an actual black hole there. If the core is a quark-gluon plasma there would then potentially be some QCD ~ AdS physics involved. The AdS physics within the BPS system might have amplitudes that are black hole-like.


  18. Dark Gnat says

    Strange, I thought black holes and neutron stars didn’t work with EU, and were just a bunch of hocus pocus.

    I guess now that there is an article that contains “neutron stars”, “plasma”, and “magnetic fields” together, everything is just fine.

  19. IVAN3MAN_AT_LARGE says

    @ Lawrence B. Crowell,

    You’re welcome! As for the question mark on the interior of a neutron star, without a few mysteries the scientific pursuit for knowledge would stop.

  20. Torbjorn Larsson OM says

    Steve, thanks for taking out the garbage!

    IVAN3MAN, thanks, that is exactly my bunny friend. I just looked again, and he is now happily munching his lettuce.

    @ LBC:

    The AdS physics within the BPS system might have amplitudes that are black hole-like.

    To bone up on this further, tangentially this reminded me, the likelihood that black hole-like coherent quantum objects exist should have gone up with the discovery of quantum many-body interactions besides simple entanglement in “everyday” Bose-Einstein condensates. It’s a long stretch, but… What do you think?

  21. Torbjorn Larsson OM says

    Aqua, you should maybe read Sean Carroll’s “From eternity to here”, I haven’t read it through by a long shot but I’m sure it answer most of your questions.

    For example it makes clear on the first pages this is an old but settled question: without some kind of global clock, forbidden by special relativity, you can’t sensibly observe a different relative rate of time itself. Since you use time to establish rate, any rate drops out of the attempted estimate.

    Btw, I think it is pretty settled that FTL is impossible, even if propositions to the contrary doesn’t make bunnies cry.

    First, there are a bunch of problems that afflict “FTL physics”, such as destabilization of gauge theories.

    Second, there is a bunch of paradoxes that immediately crop up to prevent “outs” like wormholes or Alcubierre drives to work.

    Third, in addition there is the general observation that it would implode the algorithmic complexity that physics is based on. (In essence, every “problem” would be equally easy by having any “time traveling” solution, inside or outside a computer. And that is not observed.)

    Any of those should by itself tell us that FTL physics is not to be. The third is a rather elegant “no go” theorem by itself in my mind, first proposed by Scott Aaronson I believe.

    At this time any FTL theory would have to predict all these effects and their outs and similarly for the no go, besides predicting FTL itself. That is a tall order.

  22. Torbjorn Larsson OM says

    Oh, and add ubiquitous special relativity to the physics that hints that FTL is impossible, by specifically be based on the opposite and thus predicting it as a local physics. Ever since, “FTL” has really been something of a stretch anyway.

  23. Olaf says

    Your text is a complete set of intelligent sounding words strung together with some fuzzy logic. It sounds nice but in reality it is shot down when tested scientifically word for word.

    In Star Trek they call this “technobabel”

    FTL is probably not possible, but could some cheap trick not work?

    I am thinking about quantum entanglement creating some kind of transporter beam.

    Or some machine that builds a human atom by atom. at the other side but the information how to build the person is being transmitted through the other dimensions. (Assuming that string theory is true)

    Once in a while science discovers new things like dark matter, dark energy,… So maybe in some future we might find something that could be used for FTL.

    But I do believe that with current knowledge it is scientifically impossible.

  24. Member

    FTL is over-rated. If you can fly at close to the speed of light, time dilation works to allow you to cross vast distances without ageing much – providing a) you can survive the acceleration up those speeds and b) you don’t plan to return to Earth, where hundreds, thousands or millions of years may have passed – depending on how far and how fast you have been traveling at relativistic speeds.

  25. jimhenson says

    Engels and Neely say neutron stars apply to recent experiment producing dancing vortices & antivortices dipole pairs that form stable lined smoke rings. controlled generation was achieved with lasers and at faster speeds. could the lab laser effect in gluon plasma create the spinning magnetic field emission jet from a neutron star or black hole? Neutron stars behave like superfluids having superconductive properties. Zhang Cava say topological insulators are new matter physics for a baby universe, which could be like having a neutron star model on your desktop to affordably build at home. whether they’re black holes, electron holes, vortices, magnetic fields, denser gravity regions, or the adS, Kaspi’s paper like Einstein’s grand unification must unify neutron stars with other cosmological objects perhaps by size, luminoisity, density, mass, distance, magnetic field, etc

  26. Olaf says

    I prefer to brag to my friends that did this cool FTL trip. And not to some overdeveloped humanoid figure that had time to develop a million years and now tries to put me in his science lab dissecting to see what internal clock makes me tick.

  27. IVAN3MAN_AT_LARGE says

    @ Olaf,

    Alternative scenario…

    Oh my God. I’m back. I’m home. All the time, it was… We finally really did it.

    You Maniacs! You blew it up! Ah, damn you! God damn you all to hell!

    — George Taylor, Planet of the Apes (1968).

  28. Torbjorn Larsson OM says

    Olaf, actually I forgot to mention Bell test experiments.

    Some of them are probably the most certain tests we have, I’ve heard ~ 30 sigma mentioned. And some of them test relativity really well. (Since entanglement gives correlations, one can separate them from causality.) So no, that wouldn’t work either.

    And in as much as string theory works, it is relativistic.

    What I’m arguing is that this is pretty much settled. And there won’t be any outs, cheap tricks or sorcery getting around physics any more here than elsewhere.

    I might be wrong though, even though “physics is not FTL” seems to be a thoroughly falsification tested theory as regards outs et cetera.

    I’m with Steve in this. You don’t need FTL for exploration or colonization, you want it because it would make economical and social spheres larger. More “fi” than “sci” in sci fi.

    But having no FTL is actually to the benefit of biospheres, since migration would enable local adaptation and environmental preservation in a way that a biologically coherent mono-culture would not.

    Migration would be relatively expensive but, in principle, local exploitation relatively fast and cheap. Assuming migration isn’t prohibitively expensive, I would think that is another win-win for migration as you would spread faster. (Takes tens of thousands of years to exploit planets and move on, plenty of time for adaptation, but mere centuries to get to the next system. I’m assuming “seed ships” aren’t realistic in a “no FTL” world.)

  29. Lawrence B. Crowell says

    @Torbjorn Larsson OM: Entanglements are an aspect of this sort of physics. The matter is rather subtle, but it does involve entanglements of states associated with a black hole horizon. The stuff in the core of the neutron star is probably a quark-gluon plasma. This has some correspondence with AdS and black hole physics. The AdS spacetime in three dimensions is dual to a conformal version of quantum chromodynamics (QCD), which is at high energy the physics of quark-gluon plasmas. Further, the gluonic and electric charge determine the configuration of the event horizon for a black hole, where even if the black hole does not exist there are still quantum amplitudes which are black hole like. The amplitude for the black hole scales as (g^2/4-pi)log(E_p/E), where E_p is the Planck energy or the string limiting energy (Hagedorn temperature) and E is the energy of your “probe.” There are some RHIC data which suggest this with ion collisions. I could give references and go considerably further in this, if there is interest.

    As for FTL, the problem is that this does such enormous damage to physics. It destroys some crucial elements of quantum physics, in particular that eigenstates are bounded below. It automatically implies closed timelike loops, or more generically time travel. This puts causality into question. Further, with the above I mention there is a holographic result that very high energy physics corresponds to very low energy physics, called the UV/IR correspondence. If you tried to get some FTL trick by reaching energies above the Planck energy, this correspondence blocks you, by resulting in not getting quanta in a pure state at higher energy, but multiple states in an entanglement at lower energy. Another way of seeing this is that if you could travel faster than light you could enter a black hole and record the quantum state of its interior, and bring entangled state back out. This is not permitted by the quantum Xerox, or “no cloning” theorem. It also violates the laws of thermodynamics, for in capturing states inside a black hole you can lower the entropy in a way which violates the second law of thermodynamics. Of course one probably should never say never, but faster than light travel is about as impossible as things appear.

    As for trying to use quantum entanglements as a way of communicating faster than light, that is not possible. The violation of the Bell equalities by nonlocality prevent that from being possible.


  30. Olaf says

    So the only way to travel FTL is in your dreams. LOL

  31. Lawrence B. Crowell says

    The Mott insulator is a case of a topological insulating state. A solid which transitions to an antiferromagnetic state by a quantum phase transition will with certain properties exhibit an anomalous insulating property. This involves the quantum Hall effect, which has analogies with the physics of a black hole event horizon and fields.

    As someone said, it appears you string together terms in physics together with invented terms in a way which might be describes as …. well curious.


  32. jimhenson says

    Leahy says 1 in 10 neutron stars have a secondary phase transition mechanism switched on within days or thousands of years after their supernova event. Magnetar SGR 1900+14 formed in 1998 says Wachter. Neutron stars could collapse into the highest density phase of three-flavor matter having symmetries of hyperons that breaks chiral symmetry. Colour flavour locking ferromagnetism by quark matter with the CFL phase electromagnetic insulator could be why most neutron stars transition into common magnetars or quark stars worth spotting in action.

  33. wjwbudro says

    I wonder which Muppet character Jim is acting out here.

  34. jimhenson says

    Protons, Neutrons, Quarks, Electrons. short lived Quantum particles that form stars. electron time is 10^-18 attosec. Could stars also behave as particles in a larger 3D scale or string-theory dimension in outer space? in colder space, time and motion is far slower, when mass, lumin, and size increase. Vanzella Lima say only black holes have both quantum effects and gravity, but supernovas and black holes both form from cosmological quantum effects over great distances, like in galaxy clusters and superclusters over billions of years. supernovas include neutron stars, as having cosmological unknown quantum forces that cause their formation rapidly over vast distances.

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