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Most Massive Neutron Star Ever Detected
- QueensGambit 7y agoThis newly detected neutron star is 333,000 times the mass of the Earth and 2.17 times the mass of the sun. But the star is only about 15 miles across. This is close to the limit of how much mass a compact object can contain before it crushes itself into a black hole.
- Gibbon1 7y ago> This is close to the limit of how much mass a compact object can contain before it crushes itself into a black hole. Obviously it's time for bed because reading this makes me want to toss a quarter in it to see what happens.
- arethuza 7y agoAssuming you are starting from orbit wouldn't you have to give that coin quite a "toss" to get it to change its orbit so as to hit the surface? No atmosphere to help...
- saagarjha 7y agoNot if you’re far enough away.
- sidcool 7y agoIt would get shred to fundamental particles/waves. Then its electrons would fuse inside the nucleus to form a neutron gravy.
- GlobalFrog 7y agoI'm curious as well, for example to imagine how the event would unfold, as it would not be the direct remnant of a supernova. For an observer, would the neutron star seem to just disappear? Where would be the horizon and what would it look like as it suddenly appears?
- ekimekim 7y agoI'm not a physicist, but I _think_ to my understanding what you would see is a collapse that would slow down and get more and more red-shifted, as the photons from the collapse take longer and longer to get to you (and are robbed of more and more energy, hence the red-shift). So what you would see is more of a slow fadeout as the object shrinks and gets redder and dimmer, until you can't see anything at all. In the limit as the object gets smaller and the photons get dimmer, you end up with something that emits no light and is the size of the black hole silouette.
- mnw21cam 7y agoSaying that's what you would see is a bit like saying that if you push something it will keep moving forever. It's the physicist's answer, assuming ideal conditions. In reality, the initial collapse probably won't include all the mass of the object, including any dust or gas orbiting nearby it. So your lovely "fading from sight" black hole will be there, but obscured by the raging maelstrom (always wanted to use that word) of material now circling the plug-hole around it and heated to $DEITY knows what temperature.
- imvetri 7y agoill throw equal quantity of vacuum to see if it counters your quarter :D
- Aaargh20318 7y ago> the star is only about 15 miles across According to the article it's 30 kilometers across. No need to incorrectly convert it to some medieval unit of measurement.
- romaaeterna 7y ago1. Miles are Roman, not Medieval. 2. What would be medieval would be a superstitious reaction to units of measurement as if they were purity religion cult signifiers rather than simple rational concepts to be converted between at will, depending on the task at hand.
- mcbits 7y agoThe "correct" conversion to (modern) miles would be 20, both because 30 has only one significant digit and because it makes more sense to round 18.x to 20 than to 15.
- johnr2 7y ago> The "correct" conversion to (modern) miles would be 20 In nautical miles it would be closer to 15 ;-)
- Aaargh20318 7y ago> Miles are Roman, not Medieval English miles aren't. Also, the conversion wasn't done correctly, there was no need to convert it al all, and SI units are the preferred unit of measurement in science.
- deleted 7y ago[deleted]
- romaaeterna 7y agoWho do you think ruled Britain until 410AD and give the English their mile, which is simply the word for "1000" in Latin? And I think that the press release is in error here. There was no radius measurement proposed in the Nature Astronomy paper. However, the radius in the press release is far to large. See: https://i.imgur.com/Y34OspJ.png https://i.imgur.com/Y34OspJ.png (From https://arxiv.org/pdf/1603.02698.pdf https://arxiv.org/pdf/1603.02698.pdf) Something on the order of 6-10 miles for a 2.14 M neutron star is much more appropriate. Notice that this measurement may rule out some of our models (mostly the gray lines on the left of the chart) that don't predict neutron stars this massive.
- PopeDotNinja 7y agoImagine a far future game where bored teenagers grab the family spaceship, find a neutron star just below the blackhole limit, and throw things into it until it makes the switch. How fun would that be?!
- imvetri 7y agook. black hole and neutron star are between a silver line. I understand the idea of switch you spoke about. throw void into black hole (becomes neutron star) throw little piece of black hole into neutron star (becomes black hole) aah. little theory. blackhole mass can be used to convert neutron star to a blackhole. A balance between blackhole and neutron star.
- hvidgaard 7y agoYou can turn a neutron star into a black hole, but you cannot turn a black hole into anything else, only make them bigger.
- ars 7y agoYou couldn't actually do that. Time dialation means the thrown object would never actually hit the neutron star from your POV and the black hole would never form.
- SiempreViernes 7y agoThey actually measured a mass of 2.14
- ijiiijji1 7y ago3.375e10 kg/cc
- SiempreViernes 7y agoSeems the PR people got the most important figure wrong, the measured mass is 2.14 +0.1 -0.09 M_sun, as per the preprint (and nature abstract[1]): https://arxiv.org/abs/1904.06759 https://arxiv.org/abs/1904.06759 The 2.17 M_sun figure is instead the hypothesised upper limit on the neutron star mass, derived from the equations of state that survive recent LIGO observations. [1]: https://www.nature.com/articles/s41550-019-0880-2 https://www.nature.com/articles/s41550-019-0880-2
- timwayne16 7y agoGood again
- sidcool 7y agoHow come we know what a neutron star is made up of but do not know what's inside black holes? A genuine question...
- drevil-v2 7y agoNo information leaks out a black hole. It is opaque to the normal Universe.
- perlgeek 7y agoNothing comes out of a black hole, so we can't get observations from the inside. (There are nit-picky theoretical ways in which a black hole can evaporate, keyword "Hawking Radiation", but as far as I know that hasn't been observed, because it's too weak and too far away. But even then we learn about its surface/event horizon, not its inside).
- cthalupa 7y agoWe haven't observed hawking radiation coming off of a black hole, but we have observed it in lab settings. https://iopscience.iop.org/article/10.1088/1367-2630/10/10/103001/pdf https://iopscience.iop.org/article/10.1088/1367-2630/10/10/1...
- perlgeek 7y agoI can't let this comment stand as it is. This is a "numerical observation", so a simulation. And not of a black hole, but of a model of a black hole in one dimension in a Bose-Einstein-Condensate. Nobody has created a black hole in a lab and measured its radiation.
- cthalupa 7y agoI specifically stated we have not seen it coming off of a black hole, but dismissing this as just a simulation is silly and reductionist. To do the same in a counter-argument, if I can accurately model fluid dynamics, I don't have to go drop a log in my bathtub to observe the effects. But sure, if you want, we can discount that specific study and focus on others that use different methods to detect it that aren't "just simulations" https://arxiv.org/abs/1009.4634 https://arxiv.org/abs/1009.4634 https://arxiv.org/abs/1401.6612 https://arxiv.org/abs/1401.6612
- Tepix 7y agoThis neutron star would probably collapse into a black hole, but its fast rotations prevents it from doing so. It's like the movie "Speed", just with higher stakes...
- QueensGambit 7y agoHow does this work? Is it the centrifugal force?
- johndunne 7y agoThe more correct term is angular momentum. There are 'mechanisms' that can slow the angular momentum. Angular momentum is conserved, and as the star collapses from the original total mass/radius to its new much lower radius, resulting in a high spin rate. At some point the angualar momentum (or centrifugal force) perhaps will fall to some critical value where the star collapse further. I think this would be a valuable event in terms of figuring out the equation of state and the related unanswered questios the PO mentioned? It's been years since I studied phyisics at uni.... astronomy was always me fav.
- ASalazarMX 7y agoIf neutron stars can spin that fast, it's good that they don't fling fragments of themselves. Although, if they did, those fragments would likely turn to dust outside the star's gravity.
- _Understated_ 7y agoAstronomical calculations never cease to amaze me. I am the biggest astronomy nerd and watch loads of TV shows about it (the only thing apart from dinosaur stuff that I watch on TV actually!) and when scientists talk about the numbers involved in stellar objects it still blows my mind every time. "Just a single sugar-cube worth of neutron-star material would weigh 100 million tons here on Earth, or about the same as the entire human population" I struggle to visualize that... On a side note, "'Neutron stars are as mysterious as they are fascinating', said Thankful Cromartie..." - Possibly the coolest name I've ever heard :)
- throwaway_law 7y ago>I struggle to visualize that... Scales are simultaneously intuitive and yet mind bending. Never ceases to amaze me either.
- deleted 7y ago[deleted]
- antognini 7y agoBack when I was an undergrad in astrophysics one of my professors claimed that neutron stars are the most difficult objects to model in the universe. I believe him. In order to have a good model of a neutron star you need to use pretty much every branch of physics: general relativity, quantum field theory (both QED and QCD), fluid dynamics, and statistical mechanics. And these fields have important open questions in exactly the domains that you need to apply them. So you end up needing to solve not just one open problem, but a whole bundle of them, and they all conspire to work together to make each one harder than it would be on its own. Consequently, not very much is actually known about neutron stars. One of the most important open problems in modeling neutron stars is just coming up with the most basic relationship you can, namely the "equation of state." This is simply a relationship between the density and the pressure within the neutron star. The equation of state of normal stars was effectively developed in the 19th century with the development of statistical mechanics. The equation of state of white dwarfs was developed by Chandrasekhar in the 1930s, not long after the development of quantum mechanics (and while Chandrasekhar was on a boat traveling from India to England!). But the equation of state for neutron stars is still unknown. A major consequence of the equation of state is that it predicts the maximum mass of the object. In the case of a white dwarf, Chandrasekhar showed that the equation of state implied that the maximum mass had to be about 1.44 times the mass of the Sun (this is now appropriately known as the Chandrasekhar limit). But because the equation of state of neutron stars is not known, it is not known what the maximum mass of a neutron star is. Therefore, discovering more massive neutron stars is very important because it can possibly rule out certain equations of state. This, in turn, tells us a little bit more about what physical processes are going on in the neutron star. Since the problem is so theoretically intractable astrophysicists usually have to neglect or simplify certain aspects of the physics considerably. If the equation of state that comes out of these assumptions can be ruled out, this means that one of these assumptions must be faulty, and some of the underlying physics that was neglected turns out to be important after all.
- oddthink 7y agoI worked on pulsars in grad school, and I always groused that I had to deal with ultrarelativistic plasma physics and pair-production in curved spacetime. There's a reason it's hard to come up with solid answers for these things.
- _Understated_ 7y agoHere's something that just popped into my head: If we could instanly beam a sugar-cube of Neutron Star material to earth (using the same measurements as in the article) what would happen to it? Would it just fall right through whatever it's sat on or would it instantly expand into something less dense?
- Tepix 7y agoI'm curious as well. My guess is it would expand because there's not enough mass left to overcome the strong nuclear force.
- imInGoodCompany 7y agoNot a physicist, but: "expansion" is probably understating it. My guess would be something analogous to an insanely powerful neutron bomb. Interesting thought experiment, would love to see someone do the actual maths.
- SiempreViernes 7y ago"Neutron bomb" just means a nuke that releases a lot of neutrons while not exploding quite as much. The energy density contained within a bit of neutron star matter makes a big explosion, and that will likely dominate over the more exotic processes.
- vman81 7y agoA 10cm3 cube of neutron star would weigh about a billion tonnes, comparable to a cubic km of water ice. I wonder how all that mass would behave if left to expand with all the exotic physics involved - if it would just sort of... vaporize the planet.
- kmm 7y agoWith the confining pressure of gravity gone, it would instantly and violently expand. The intense 10^32 pascals of degeneracy pressure drop quickly with expansion, but even just assuming it can expand 5 ml at that pressure, the energy released would be 5e26 joules. That's about 1000 times the asteroid that made the dinosaurs extinct. It would certainly imply the end of all multicellular life. If somehow you could keep it confined, it would drop through whatever it was put on, through the entire Earth, and pop up at the other side. I suppose it would keep oscillating and eventually settle in the core.
- sytelus 7y agoIt's only 4600 light years away. If it collapses in to blackhole, it would be the closest blackhole to the earth? In few 10s of thousands of year, can it devour solar system?
- pnako 7y agoIts mass would not change, so it should not affect other objects more than it does at the moment (I think).
- short_sells_poo 7y agoThis is correct. It is a common misconception that the gravity an object exerts on it's surrounding increases when it collapses into a black hole. What actually happens is that the object shrinks - according the to the currently accepted models into a single dimensional point. The mass now being confined to a singularity, the gradient of the gravity as you get near becomes extreme, reaching infinity at the singularity. The gradient never could get so extreme before because the mass was diffused over a much bigger volume. Imagine replacing the Sun with a black hole of equal mass. Apart from the lack of visible light, the gravity we here on Earth would experience would be exactly the same as before, as would every single planet that is currently orbiting. What would change is the distribution of mass inside the sun. The event horizon would be at about 6kms from the Singularity. You could now hypothetically approach the Sun to within ~10km from the center and still stay outside of the event horizon, but the gravity gradient at that point would be unimaginable. The difference in force applied to a the feet and the head of a hypothetical astronaut in orbit would disintegrate them into atoms, which themselves would possibly be squished into spindles. With the sun as it is currently, even if you could somehow get to within 10kms of the center, the majority of the mass of the sun would be actually outside of this sphere so the net gravity you'd experience would be negligible (compared to the black hole scenario).
- GistNoesis 7y agoNot a physicist, but isn't the whole point of black hole that they can grow. The way I picture it, is once you reach the black-hole state, there is a regime change which make it more easy to gulp matter in. I guess how big and how fast it grows depends how much mass there is nearby to concentrate. Once formed they tend to an equilibrium with their surrounding dictated by the balance mass-in/evaporation-out.
- known 7y agoA matchbox sized neutron-star would weigh 3 billion tons. https://clearlyexplained.com/neutron-stars/index.html https://clearlyexplained.com/neutron-stars/index.html
- imvetri 7y agoCan the mass density of atom's nuclei match such kind of object ? On a scale of atom, this star and black hole what would be the mass density ?
- oddthink 7y agoIt's about nuclear density. Neutron stars are held up by neutron degeneracy pressure. Another fun fact is that the magnetic field energy density alone near the surface of a pulsar (1e12 gauss and up) is about that of lead. (~40 g/cm^3).
- ttul 7y agoWhat does that even mean in any sort of a human-relatable way? What would happen to your body in the presence of such a strong magnetic field?
- DanTheManPR 7y agoThere's not really a way to convey it in human terms. It's as if the magnetic field flowing through your body had the same energy as if you ate a slug of mixed lead and anti-lead with the same volume as your body, and it was undergoing matter/antimatter annihilation while it was in your stomach.
- oddthink 7y agoAtoms don’t work in that kind of a field, let alone molecules. Nothing wants to go across field lines, just along them.
- duxup 7y agoCan anyone describe why Neutron stars are more mysterious / confusing than say a black hole? A black hole seems to be just the next "step" in terms of something super-massive, but then why are neutron star's more of a mystery?
- antognini 7y agoThe main reason is that while black holes are more "extreme" objects, they are actually physically very simple. The matter collapses to a singularity (as far as we know), and so the physics is just described by the Einstein field equations with a correction for quantum fluctuations near the event horizon. Remarkably, the entire state of the black hole can be described by only the mass, charge, and angular momentum of the black hole. By contrast, although neutron stars are less "extreme", they end up in a regime where the physics becomes much more difficult. The gravity is strong enough that you still need general relativity, but because the object is extended rather than a singularity, there's also a bunch of "stuff" which needs to be described as well. This means that you need to add in quantum electrodynamics and quantum chromodynamics. Furthermore, it's thought that at these densities you end up with some sort of a superfluid which means you need fluid dynamics and statistical physics to model its behavior, all of which is extremely difficult. That said, there is another sense in which we could say that black holes are actually more mysterious than neutron stars. Although the physics of neutron stars is very complicated, we at least know what all the fundamental equations are. In the case of black holes if we want to understand physics near the singularity we would need a theory of quantum gravity which we currently don't have.
- PorterDuff 7y agoIs there some reason for all neutron stars to have the same physical make-up and internal behavior? or could they fall into types?
- antognini 7y agoIt is entirely possible that there could be different types of neutron stars, although the same physics will describe them all. As an analogy, white dwarfs all have the same equation of state, but based on the mass of the white dwarf the electrons can either be relativistic or non-relativistic. (This is not really a true dichotomy, it's just a spectrum.) There could plausibly be something similar with neutron stars.
- hi41 7y agoThe article refers to a neutron star being a giant atomic nuclei. How did this happen? The mass of the neutron star and the star before the collapse are similar. so why did the matter change into atomic nuclei? This makes me think that gravity is not the only thing at play here; density also matters. Is my this correct? So, is gravity dependent on the density? I guess I am confused.
- Ancalagon 7y agoThe mass of the neutron star is _not_ the same as the entire star before it. The neutron star is (mostly) core material from its parent star, the rest of the matter was likely flung out upon that stars death. Gravity is not the only thing at play, strong nuclear forces between atoms prevent the star from collapsing under its own gravity, as well as the angular momentum of the stars spin. The neutron star is one giant atomic nuclei in the sense that all of its atoms are incredibly densely packed together. Imagine a styrofoam ball that you put under immense pressure from all angles (say by putting it deep under water). The air/free space in the styrofoam is squeezed out, and this in a sense is the same thing that happens to the plasma inside the parent star's core as it collapses. All of the atoms are squeezed together, and a balancing act is created whereby the incredible density of the core is trying to pull the matter inwards (into a black hole), while the strong nuclear force/momentum are pushing back to prevent the star from collapsing further.
- hi41 7y agoThank you for the explanation.
- ncmncm 7y agoHalf the pulsars we see could be this big, or even bigger. This is just a rare one they could measure.